Six Flags Entertainment DEFM14AProxy related to merger

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

Filed by the Registrant ☒

Filed by a Party other than the Registrant ☐

Check the appropriate box:

Six Flags Entertainment Corporation

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):

MERGER PROPOSED – YOUR VOTE IS VERY IMPORTANT

Dear Stockholders of Six Flags Entertainment Corporation:

You are cordially invited to attend the special meeting (the “Six Flags Special Meeting”) of stockholders (the “Six Flags Stockholders”) of Six Flags Entertainment Corporation, a Delaware corporation (“Six Flags”), which will be held at 10:00 a.m. Central Time, on March 12, 2024 at Six Flags Entertainment Corporation Corporate Headquarters, Choctaw Stadium, 1000 Ballpark Way, Arlington, TX 76011. On behalf of the board of directors of Six Flags (the “Six Flags Board”), we are pleased to enclose the accompanying proxy statement/prospectus relating to the merger of equals business combination between Six Flags and Cedar Fair, L.P., a Delaware limited partnership (“Cedar Fair”), which will be considered at the Six Flags Special Meeting. We are requesting that you take certain actions as a Six Flags Stockholder.

On November 2, 2023, Six Flags, Cedar Fair, CopperSteel HoldCo, Inc., a Delaware corporation (“CopperSteel”) and a subsidiary of Six Flags and Cedar Fair and CopperSteel Merger Sub, LLC a Delaware limited liability company (“Copper Merger Sub”) and a wholly owned subsidiary of CopperSteel, entered into an Agreement and Plan of Merger (the “Merger Agreement”), providing for a merger of equals through (i) the merger of Copper Merger Sub with and into Cedar Fair (the “Cedar Fair First Merger”), with Cedar Fair continuing its existence as the surviving entity (the “Cedar Fair Surviving Entity”) following the Cedar Fair First Merger as a direct subsidiary of CopperSteel, (ii) the subsequent merger of the Cedar Fair Surviving Entity with and into CopperSteel (the “Cedar Fair Second Merger” and together with the Cedar Fair First Merger, the “Cedar Fair Mergers”), with CopperSteel continuing as the surviving corporation, and (iii) the subsequent merger of Six Flags with and into CopperSteel, with CopperSteel continuing as the surviving corporation (the “Six Flags Merger” and together with the Cedar Fair Mergers, the “Mergers”).

If the Mergers are completed, subject to certain exceptions, (i) each issued and outstanding unit of limited partnership interest in Cedar Fair (each a “Cedar Fair Unit” and collectively, the “Cedar Fair Units”) will be converted into the right to receive one (1) share of common stock, par value $0.01 per share, of CopperSteel (the “CopperSteel Common Stock”), as may be adjusted pursuant to the Merger Agreement (the “Cedar Fair Exchange Ratio”), together with cash in lieu of fractional shares of CopperSteel Common Stock, without interest and (ii) each issued and outstanding share of common stock, par value $0.025 per share, of Six Flags (the “Six Flags Common Stock”) will be converted into the right to receive 0.5800 shares of CopperSteel Common Stock, as may be adjusted pursuant to the Merger Agreement (the “Six Flags Exchange Ratio”), together with cash in lieu of fractional shares of CopperSteel Common Stock, without interest. Subject to the terms of the Merger Agreement and applicable law, Six Flags will declare and set a record date for a special dividend to holders of record of Six Flags Common Stock as of the close of business one business day prior to the closing of the Mergers (the “Closing” and with respect to the dividend, the “Special Dividend”) of (a) $1.00 plus (b) the product (rounded to the nearest whole cent) of (i) the Six Flags Exchange Ratio and (ii) the aggregate amount of distributions per unit declared or paid by Cedar Fair with respect to a Cedar Fair Unit with a record date following the date of the Merger Agreement and prior to the effective time of the Six Flags Merger (the “Closing Effective Time”), subject to certain adjustments provided under the Merger Agreement, the payment of which is contingent upon the consummation of the Mergers.

Following the completion of the Mergers, it is anticipated that persons who were Six Flags Stockholders and unitholders of Cedar Fair (the “Cedar Fair Unitholders”) immediately prior to the Mergers will own

approximately 48.8% and 51.2% of CopperSteel Common Stock, respectively, on a fully diluted basis. Upon consummation of the Mergers, Six Flags and Cedar Fair will each have been merged with and into CopperSteel, with CopperSteel as the parent entity and successor corporation to Six Flags and Cedar Fair. Upon Closing, CopperSteel will be headquartered in Charlotte, North Carolina, and is expected to change its name to “Six Flags Entertainment Corporation” and be listed on the New York Stock Exchange (“NYSE”) under the ticker symbol “FUN.”

The obligations of Six Flags and Cedar Fair to complete the Mergers are subject to the satisfaction or waiver, in whole or in part (to the extent permitted by applicable law) of a number of conditions set forth in the Merger Agreement, a copy of which is attached as Annex A to the accompanying proxy statement/prospectus. Completion of the Mergers requires, among other things, the adoption of the Merger Agreement by the Six Flags Stockholders. To obtain the required stockholder approval, Six Flags will hold the Six Flags Special Meeting.

At the Six Flags Special Meeting, the Six Flags Stockholders will be asked to vote on (1) a proposal to adopt the Merger Agreement and the transactions contemplated therein, including the Mergers (the “Merger Agreement Proposal”); (2) a proposal to approve, on a non-binding advisory basis, the compensation that may be paid or become payable to Six Flags’ named executive officers that is based on or otherwise relates to the Mergers (the “Compensation Advisory Proposal”); and (3) a proposal to adjourn the Six Flags Special Meeting, if necessary, to a later date or dates at the determination of the Six Flags Board, including to solicit additional proxies in favor of the Merger Agreement Proposal if there are insufficient votes at the time of the Six Flags Special Meeting to approve the Merger Agreement Proposal or to ensure that any supplement or amendment to this proxy statement/prospectus is timely provided to Six Flags Stockholders (the “Adjournment Proposal”). The Six Flags Board unanimously recommends that the Six Flags Stockholders (i) vote “FOR” the Merger Agreement Proposal; (ii) vote “FOR” the Compensation Advisory Proposal; and (iii) vote “FOR” the Adjournment Proposal.

Approval of the Merger Agreement Proposal requires the affirmative vote of the holders of a majority of the outstanding shares of Six Flags Common Stock entitled to vote in person or by proxy thereon. The Mergers cannot be completed without the approval of the Merger Agreement Proposal. Approval of the Compensation Advisory Proposal, on a non-binding advisory basis, requires the affirmative vote of holders of a majority of the shares of Six Flags Common Stock present in person or represented by proxy at the Six Flags Special Meeting and entitled to vote thereon. The approval of the Compensation Advisory Proposal is not a condition to Closing or otherwise required to effectuate the Mergers. The completion of the Mergers does not require the approval of the Cedar Fair Unitholders. Approval of the Adjournment Proposal requires the affirmative vote of holders of a majority of the shares of Six Flags Common Stock present in person or represented by proxy at the Six Flags Special Meeting and entitled to vote thereon, even if a quorum is not present at the Six Flags Special Meeting. The accompanying proxy statement/prospectus describes the Six Flags Special Meeting, the Merger Agreement Proposal, the Compensation Advisory Proposal and the Adjournment Proposal to be considered thereat and the Mergers. Please carefully read the entire accompanying proxy statement/prospectus, including the section entitled, “Risk Factors”, for a discussion of the risks relating to the Mergers. You also can obtain information about Six Flags and Cedar Fair from documents that each has filed with the Securities and Exchange Commission (the “SEC”). Please see the section entitled, “Where You Can Find More Information” of the accompanying proxy statement/prospectus for how you may obtain such information.

Your vote is very important. To ensure your representation at the Six Flags Special Meeting, please complete and return the enclosed proxy card or submit your proxy by following the instructions contained in this proxy statement/prospectus and on your proxy card. Please submit your proxy promptly whether or not you expect to participate in the Six Flags Special Meeting. Submitting a proxy now will NOT prevent you from being able to vote at the Six Flags Special Meeting. If you hold your shares in “street name”, you should instruct your broker, bank or other nominee how to vote in accordance with the voting instruction form you receive from your broker, bank or other nominee.

In considering the recommendation of the Six Flags Board that Six Flags Stockholders vote “FOR” the Merger Agreement Proposal, Six Flags Stockholders should be aware that, aside from their interests as

Six Flags Stockholders, Six Flags’ directors and executive officers have interests in the Mergers that may be different from, or in addition to, the interests of Six Flags Stockholders generally. These interests are described in more detail in the accompanying proxy statement/prospectus in the section entitled “The Mergers — Interests of Certain Six Flags Directors and Executive Officers in the Mergers.”

On behalf of the Six Flags Board, I would like to thank you for your support of Six Flags and look forward to a successful completion of the Mergers.

Sincerely,

/s/ Selim Bassoul

Selim Bassoul

Chief Executive Officer

Six Flags Entertainment Corporation

Neither the SEC nor any state securities commission has approved or disapproved of the securities to be issued in connection with the transactions described in the accompanying proxy statement/prospectus or determined if the accompanying proxy statement/prospectus is accurate or complete. Any representation to the contrary is a criminal offense.

The accompanying proxy statement/prospectus is dated January 31, 2024, and is first being mailed to Six Flags Stockholders of record on or about February 1, 2024.

NOTICE OF SPECIAL MEETING OF STOCKHOLDERS

TO BE HELD ON MARCH 12, 2024

Dear Stockholder:

You are cordially invited to attend the special meeting (the “Six Flags Special Meeting”) of stockholders (the “Six Flags Stockholders”) of Six Flags Entertainment Corporation, a Delaware corporation (“Six Flags”), to be held at 10:00 a.m., Central Time, on March 12, 2024. The Six Flags Special Meeting will be held in person at Six Flags Entertainment Corporation Corporate Headquarters, Choctaw Stadium, 1000 Ballpark Way, Arlington, TX 76011. At the Six Flags Special Meeting you will be asked to consider and vote on the following proposals:

Six Flags will transact no other business at the Six Flags Special Meeting, except such business as may properly be brought before the Six Flags Special Meeting or any adjournments or postponements thereof by or at the direction of the Six Flags Board in accordance with Six Flags’ second amended and restated bylaws. This proxy statement/prospectus, of which this notice is a part, describes the proposals listed above in more detail. Please refer to the attached documents, including the Merger Agreement and all other annexes and any documents incorporated by reference, for further information with respect to the business to be transacted at the Six Flags Special Meeting. You are encouraged to read the entire document carefully. In particular, please see the sections entitled “The Mergers” for a description of the transactions contemplated by the Merger Agreement and “Risk Factors” for an explanation of the risks associated with the Mergers and the other transactions contemplated by the Merger Agreement.

The Six Flags Board has fixed the close of business on January 24, 2024 as the record date for the determination of the Six Flags Stockholders entitled to receive notice of, and to vote at, the Six Flags Special Meeting or any adjournments or postponements thereof. Only Six Flags Stockholders of record on the record date are entitled to receive notice of, and to vote at, the Six Flags Special Meeting or any adjournments or postponements thereof. For additional information regarding the Six Flags Special Meeting, please see the section entitled “Six Flags Special Meeting” of this proxy statement/prospectus, of which this notice is a part.

After careful consideration, the Six Flags Board has unanimously approved the Merger Agreement and the transactions contemplated thereby and determined that each of the proposals to be presented at the Six Flags Special Meeting is in the best interest of Six Flags and its stockholders. The Six Flags Board unanimously recommends that the Six Flags Stockholders vote “FOR” the Merger Agreement Proposal, “FOR” the Compensation Advisory Proposal and “FOR” the Adjournment Proposal.

As a Six Flags Stockholder, you play an important role in Six Flags by considering and taking action on these matters. We appreciate the time and attention you invest in making thoughtful decisions.

Please vote as promptly as possible, whether or not you plan to attend the Six Flags Special Meeting. If your shares are held in the name of a broker, bank or other nominee, please vote by following the instructions on the voting instruction form furnished by the broker, bank or other nominee. If you hold your shares in your own name, please submit a proxy to vote your shares as promptly as possible by (i) visiting the internet site listed on the proxy card, (ii) calling the toll-free number listed on the proxy card or (iii) signing and returning your proxy card by mail by using the self-addressed, stamped envelope provided. Submitting a proxy will not prevent you from voting at the Six Flags Special Meeting, but it will help to secure a quorum and avoid added solicitation costs. Any eligible holder of Six Flags common stock entitled to vote thereon and who is present at the Six Flags Special Meeting may vote at the Six Flags Special Meeting, thereby revoking any previous proxy. In addition, a proxy may also be revoked before the voting polls are closed at the Six Flags Special Meeting in the manner described in this proxy statement/prospectus, of which this notice is a part.

If you have any questions concerning the Merger Agreement Proposal, the Compensation Advisory Proposal, the Adjournment Proposal, the Mergers, or this proxy statement/prospectus, of which this notice is a part, would like additional copies or need help voting your shares of Six Flags common stock, please contact Six Flags’ proxy solicitors:

Innisfree M&A Incorporated

501 Madison Avenue, 20^th Floor

New York, New York 10022

Banks and Brokerage Firms, Please Call: (212) 750-5833

Stockholders and All Others Call Toll Free: (877) 750-0854

ADDITIONAL INFORMATION

Both Six Flags and Cedar Fair file annual, quarterly, and current reports, proxy statements and other business and financial information with the SEC electronically, and the SEC maintains a website located at www.sec.gov containing this information. You can also obtain these documents, free of charge, from Six Flags at www.sixflags.com/ and from Cedar Fair at www.cedarfair.com/, as applicable. The information contained on, or that may be accessed through, Six Flags’ and Cedar Fair’s websites is not incorporated by reference into, and is not a part of, this proxy statement/prospectus.

This proxy statement/prospectus incorporates important business and financial information about Six Flags and Cedar Fair from documents that are not attached to this proxy statement/prospectus. This information is available to you without charge upon your request. You can obtain the documents incorporated by reference into this proxy statement/prospectus, including copies of financial statements and management’s discussion and analysis, free of charge by requesting them in writing or by telephone from the appropriate company or, in the case of Six Flags, its proxy solicitor, at the following addresses and telephone numbers:

If you would like to request any documents, please do so by March 5, 2024, which is five business days prior to the date of the Six Flags Special Meeting, in order to receive them before the Six Flags Special Meeting.

For a more detailed description of the information incorporated by reference into this proxy statement/prospectus and how you may obtain it, please see the section entitled “Where You Can Find More Information.”

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ABOUT THIS PROXY STATEMENT/PROSPECTUS

CopperSteel has filed with the SEC a registration statement on Form S-4 (File No. 333-276255), of which this proxy statement/prospectus forms a part. This proxy statement/prospectus constitutes the prospectus of CopperSteel under Section 5 of the Securities Act of 1933, as amended (the “Securities Act”) with respect to shares of CopperSteel Common Stock issuable to Six Flags Stockholders and Cedar Fair Unitholders in the Mergers pursuant to the Merger Agreement. Additionally, this proxy statement/prospectus also constitutes a proxy statement under Section 14(a) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), with respect to Six Flags. It also constitutes a notice of meeting with respect to the Six Flags Special Meeting. As permitted by SEC rules, this proxy statement/prospectus does not contain all of the information included in the registration statement or in the exhibits or schedules to the registration statement. You may read and copy the registration statement, including any amendments, schedules and exhibits, at the SEC’s website mentioned above. Statements contained in this proxy statement/prospectus as to the contents of any contract or other documents referred to in this proxy statement/prospectus are not necessarily complete. In each case, you should refer to the copy of the applicable agreement or other document filed as an exhibit to the registration statement.

Information contained in or incorporated by reference into this proxy statement/prospectus relating to Six Flags has been supplied by Six Flags. Information contained in this proxy statement/prospectus relating to Cedar Fair has been supplied by Cedar Fair.

You should rely only on the information contained in or incorporated by reference into this proxy statement/prospectus. No one has been authorized to provide you with information that is different from that contained in, or incorporated by reference into, this proxy statement/prospectus. This proxy statement/prospectus is dated January 31, 2024, and you should assume that the information contained in this proxy statement/prospectus is accurate only as of such date. You should also assume that the information incorporated by reference into this proxy statement/prospectus is only accurate as of the date of such information. Neither the mailing of this proxy statement/prospectus to Six Flags Stockholders nor the issuance by CopperSteel of shares of CopperSteel Common Stock pursuant to the Merger Agreement will create any implication to the contrary.

This proxy statement/prospectus does not constitute an offer to sell, or a solicitation of an offer to buy, any securities, or the solicitation of a proxy in any jurisdiction to or from any person to whom it is unlawful to make any such offer or solicitation in such jurisdiction. Information contained in this proxy statement/prospectus regarding Six Flags has been provided by Six Flags, and information contained in this proxy statement/prospectus regarding Cedar Fair has been provided by Cedar Fair.

All currency amounts referenced in this proxy statement/prospectus are in U.S. dollars. All references in this proxy statement/prospectus to:

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TABLE OF CONTENTS

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QUESTIONS AND ANSWERS

The following are some questions that you may have regarding the Mergers and other matters being considered at the Six Flags Special Meeting and the answers to those questions. Six Flags and Cedar Fair urge you to carefully read the entirety of this proxy statement/prospectus, including the annexes hereto and the information incorporated herein, because the information in this section does not provide all the information that might be important to you with respect to the Mergers and other matters being considered at the Six Flags Special Meeting.

The Mergers cannot be completed without the approval of the Merger Agreement Proposal. To obtain the required stockholder approvals, Six Flags will hold the Six Flags Special Meeting in connection with the Mergers.

The Mergers cannot be completed without the approval of the Merger Agreement Proposal. The approval of the Compensation Advisory Proposal is not a condition to the Closing or otherwise required to effectuate the Mergers.

This proxy statement/prospectus, which you should read carefully, contains important information about the Mergers, the Merger Agreement Proposal, the Compensation Advisory Proposal and the Adjournment Proposal.

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Additionally, subject to the terms of the Merger Agreement and applicable law, Six Flags will declare the Special Dividend to holders of record of Six Flags Common Stock as of the close of business one business day prior to the Closing of (a) $1.00 plus (b) the product (rounded to the nearest whole cent) of (i) the Six Flags Exchange Ratio and (ii) the aggregate amount of distributions per unit declared or paid by Cedar Fair with respect to a Cedar Fair Unit with a record date following the date of the Merger Agreement and prior to the Closing Effective Time, subject to certain adjustments provided under the Merger Agreement, the payment of which is contingent upon the consummation of the Mergers.

For additional information regarding the consideration to be received in the Mergers, please see the section entitled “The Mergers — What Stockholders and Unitholders Will Receive in the Mergers and Potential Adjustments — Six Flags Merger Consideration.”

For additional information regarding the consideration to be received in the Mergers, please see the section entitled “The Mergers — What Stockholders and Unitholders Will Receive in the Mergers and Potential Adjustments — Cedar Fair Merger Consideration.”

If you are a holder of book-entry Eligible Shares (“Six Flags Book-Entry Shares”) which are held through the Depository Trust Company (“DTC”), the Exchange Agent will transmit to DTC or its nominees as soon as reasonably practicable on or after the Closing Date, the Six Flags Merger Consideration, cash in lieu of any fractional shares of CopperSteel Common Stock issuable as Six Flags Merger Consideration that DTC has the right to receive.

If you are a holder of record of Six Flags Book-Entry Shares which are not held through DTC, the Exchange Agent will deliver to you, as soon as practicable after the Closing Effective Time, (i) a notice advising you

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of the effectiveness of the Mergers, (ii) a statement reflecting the aggregate whole number of shares of CopperSteel Common Stock (which will be in uncertificated book-entry form) that you have a right to receive pursuant to the Merger Agreement and (iii) an amount in cash equal to the cash payable in lieu of any fractional shares of CopperSteel Common Stock issuable to you as Six Flags Merger Consideration.

No interest will be paid or accrued on any amount payable for shares of Six Flags Common Stock eligible to receive the Six Flags Merger Consideration pursuant to the Merger Agreement.

In addition, contingent upon the consummation of the Mergers, holders of record of Six Flags Common Stock as of the close of business one business day prior to the Closing will receive from the Exchange Agent (or through DTC, in the case of holders of Six Flags Book-Entry Shares) an amount in cash equal to the Special Dividend to which such holders are entitled.

For additional information on the exchange of Six Flags Common Stock for the Six Flags Merger Consideration, see the section entitled “The Merger Agreement — Exchange Fund.”

If you are a holder of book-entry units representing the eligible Cedar Fair Units (a “Cedar Fair Book-Entry Unit”) which are held through DTC, the Exchange Agent will transmit to DTC or its nominees as soon as reasonably practicable on or after the Closing Date, the Cedar Fair Merger Consideration, cash in lieu of any fractional shares of CopperSteel Common Stock issuable as Cedar Fair Merger Consideration that DTC has the right to receive.

If you are a holder of record of Cedar Fair Book-Entry Units which are not held through DTC, the Exchange Agent will deliver to you, as soon as practicable after the Closing Effective Time, (i) a notice advising you of the effectiveness of the Mergers, (ii) a statement reflecting the aggregate whole number of shares of CopperSteel Common Stock (which will be in uncertificated book-entry form) that you have a right to receive pursuant to the Merger Agreement and (iii) an amount in cash equal to the cash payable in lieu of any fractional shares of CopperSteel Common Stock issuable to you as Cedar Fair Merger Consideration.

No interest will be paid or accrued on any amount payable for Cedar Fair Units eligible to receive the Cedar Fair Merger Consideration pursuant to the Merger Agreement.

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For additional information on the treatment of Six Flags Equity Awards, please see the section entitled “The Merger Agreement — Treatment of Six Flags Equity Awards in the Mergers”, and for additional information on the differing treatment of Six Flags RSU Awards and Six Flags PSU Awards held by Messrs. Bassoul and Mick (the two Six Flags executive officers), see the section entitled “The Mergers —Interests of Certain Six Flags Directors and Executive Officers in the Mergers — Treatment of Six Flags Equity Awards Held by Six Flags Executive Officers.”

For additional information on the treatment of Cedar Fair Equity Awards, please see the section entitled “The Merger Agreement — Treatment of Cedar Fair Equity Awards in the Mergers.”

Accordingly, as a result of the Six Flags Merger, Six Flags U.S. holders (as defined in the section entitled “Material U.S. Federal Income Tax Consequences for Six Flags Holders” of this proxy statement/prospectus) will not recognize gain or loss for U.S. federal income tax purposes in the Six Flags Merger (other than with respect to the receipt of cash in lieu of fractional shares).

For more information on the material U.S. federal income tax consequences of the Six Flags Merger, see the section entitled “Material U.S. Federal Income Tax Consequences for Six Flags Holders” of this proxy statement/prospectus. Six Flags Stockholders are strongly urged to consult with their tax advisors about the

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tax consequences of the Six Flags Merger to them, including the effects of U.S. federal, state and local, foreign and other tax laws.

Nevertheless, the U.S. federal income tax treatment of the Special Dividend is not free from doubt. See the section entitled “Material U.S. Federal Income Tax Consequences for Six Flags Holders” of this proxy statement/prospectus for more information on the material U.S. federal income tax consequences of the Special Dividend, including potential alternative characterizations of the Special Dividend for U.S. federal income tax purposes. Six Flags Stockholders are strongly urged to consult with their tax advisors about the tax consequences of the Special Dividend to them, including the effects of U.S. federal, state and local, foreign and other tax laws.

Accordingly, subject to such limitations and qualifications, Cedar Fair Unitholders will not recognize gain or loss on the exchange of Cedar Fair Units for CopperSteel Common Stock, except that gain may be recognized with respect to certain liabilities treated as assumed by CopperSteel and cash received in lieu of a fractional share of CopperSteel Common Stock. If a Cedar Fair Unitholder recognizes gain, a portion of this gain may be separately computed and taxed as ordinary income under Section 751 of the Code to the extent attributable to “unrealized receivables,” including depreciation recapture or to “inventory items” owned by Cedar Fair. Otherwise such gain recognized generally will be long-term capital gain, provided certain holding period and other requirements are met. In addition to the tax consequences described above, Cedar Fair non-U.S. holders (as defined in the section entitled “Material U.S. Federal Income Tax Consequences for Cedar Fair Unitholders” of this proxy statement/prospectus) will be subject to withholding under Section 1446(f) of the Code with respect to the CopperSteel Common Stock received.

For more information on the material U.S. federal income tax consequences of the Cedar Fair First Merger, see the section entitled “Material U.S. Federal Income Tax Consequences for Cedar Fair Unitholders” of this proxy statement/prospectus. Cedar Fair Unitholders are strongly urged to consult with their tax advisors

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about the tax consequences of the Cedar Fair First Merger to them, including the effects of U.S. federal, state and local, foreign and other tax laws.

Additionally, the Merger Agreement provides that, at the Closing Effective Time, (i) Mr. Zimmerman, current President and Chief Executive Officer of Cedar Fair, will serve as President and Chief Executive Officer of CopperSteel, (ii) Mr. Bassoul, current President and Chief Executive Officer of Six Flags, will serve as Executive Chairman of the CopperSteel Board, (iii) Mr. Gary Mick, current Chief Financial Officer of Six Flags, will serve as Chief Integration Officer of CopperSteel and (iv) Mr. Brian Witherow, current Chief Financial Officer of Cedar Fair, will serve as Chief Financial Officer of CopperSteel.

The Mergers cannot be completed without the approval of the Merger Agreement Proposal. The approval of the Compensation Advisory Proposal is not a condition to the Closing or otherwise required to effectuate the Mergers.

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Following the Mergers, as a result of the Cedar Fair Exchange Ratio and Six Flags Exchange Ratio, it is expected that Cedar Fair Unitholders who hold the issued and outstanding Cedar Fair Units immediately prior to the Cedar Fair First Merger Effective Time will own approximately 51.2% of the outstanding shares of CopperSteel Common Stock and the shareholders of Six Flags Common Stock will own approximately 48.8% of the outstanding shares of CopperSteel Common Stock.

In addition, the Merger Agreement provides for certain adjustments to the Cedar Fair Exchange Ratio, Six Flags Exchange Ratio, the Cedar Fair Merger Consideration, the Six Flags Merger Consideration or the amount of the Special Dividend to ensure that the Cedar Fair Merger Consideration amounts to the aggregate number of shares of CopperSteel Common Stock representing at least 51.01% of the voting power of all issued and outstanding shares of CopperSteel Common Stock immediately following the Closing Effective Time. Therefore, following the Mergers, Cedar Fair Unitholders who hold Cedar Fair Units outstanding immediately prior to the Mergers will hold greater than 51% of the voting interest of CopperSteel post-Closing. Consequently, the completion of the Mergers does not require the approval of Cedar Fair’s Unitholders. The structure of the Mergers, set forth in further detail in the section entitled “The Merger Agreement — Structure of the Mergers,” does not impact the required vote or approval of Cedar Fair’s Unitholders.

Cedar Fair Unitholders are not being asked for a proxy and they are requested not to send a proxy.

For additional information please see the sections entitled “The Merger Agreement — Exchange Ratio Adjustments to Prevent Dilution” and “The Merger Agreement — Merger Consideration.”

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Prior to or upon consummation of the Mergers, the parties shall cause the name of CopperSteel to change to “Six Flags Entertainment Corporation” and to list the shares of CopperSteel Common Stock on NYSE under the ticker symbol “FUN”.

In addition, each of Six Flags’ and Cedar Fair’s respective obligations to complete the Mergers is subject to, among other conditions, the accuracy of the other party’s representations and warranties in the Merger Agreement (subject in most cases to “materiality” and “material adverse effect” qualifications), the other party’s compliance with its covenants and agreements in the Merger Agreement in all material respects.

For a more complete summary of the Closing Conditions that must be satisfied or waived prior to the completion of the Mergers, please read the section entitled “The Merger Agreement — Conditions to Completion of the Mergers.”

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Under specified circumstances, Six Flags may be required to pay a termination fee upon or subsequent to termination of the Merger Agreement, as described in “The Merger Agreement — Expenses and Termination Fees.”

A quorum at the Six Flags Special Meeting requires a majority of the outstanding shares of Six Flags Common Stock entitled to vote. The shares may be present in person or represented by proxy at the Six Flags Special Meeting. We do not expect brokers to have discretionary voting authority and therefore there will not be any broker non-votes.

For additional information on voting procedures, please see the section entitled “Six Flags Special Meeting.”

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If your shares of Six Flags Common Stock are held through a bank, broker or other nominee, you are considered, with respect to those shares, the beneficial owner, and those shares are held in “street name” by your bank, broker or other nominee. In that case, this proxy statement/prospectus has been forwarded to you by your bank, broker or other nominee. As the beneficial owner, you have the right to direct your bank, broker or other nominee how to vote your shares by following their instructions for voting, and you are also invited to attend the Six Flags Special Meeting. However, because you are not the stockholder of record, you may not vote your shares of Six Flags Common Stock at the Six Flags Special Meeting unless you request and obtain a “legal proxy” issued in your own name from your bank, broker or other nominee.

You should instruct your bank, broker or other nominee how to vote your shares of Six Flags Common Stock. Under the rules applicable to broker-dealers, your bank, broker or other nominee does not have discretionary authority to vote your shares on any of the proposals scheduled to be presented at the Six Flags Special Meeting. A broker non-vote occurs when a broker or other nominee does not receive voting instructions from the beneficial owner and does not have the discretion to direct the voting of the shares. A broker is entitled to vote shares held for a beneficial holder on routine matters without instructions from the beneficial holder of those shares. However, a broker is not entitled to vote shares held for a beneficial holder on non-routine items, such as the Merger Agreement Proposal, the Compensation Advisory Proposal and the Adjournment Proposal and therefore there will not be any broker non-votes.

For additional information on voting procedures, please see the section entitled “Six Flags Special Meeting.”

For additional information on voting procedures, please see the section entitled “Six Flags Special Meeting.”

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If you are a beneficial owner of shares of Six Flags Common Stock, you are also invited to attend the Six Flags Special Meeting. However, because you are not the Six Flags Stockholder of record, you may not vote your shares in person at the Six Flags Special Meeting unless you request and obtain a “legal proxy” issued in your own name from your bank, broker or other nominee.

If you appoint a non-management proxy holder, please make sure he or she is aware and ensure he or she will attend and submit a vote on your behalf at the Six Flags Special Meeting, with the proper authority from you, for your vote to count.

For additional information on attending the Six Flags Special Meeting, please see the section entitled “Six Flags Special Meeting.”

Beneficial owners of shares of Six Flags Common Stock may submit new voting instructions by contacting their broker, bank or other holder of record.

For additional information, please see the section entitled “Six Flags Special Meeting.”

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For more information regarding dissenters’ or appraisal rights, please see the section entitled “The Mergers — Appraisal Rights and Dissenters’ Rights.”

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Investor Relations

Six Flags Entertainment Corporation.

1000 Ballpark Way, Suite 400

Arlington, Texas 76011

(972) 595-5000

Innisfree M&A Incorporated

501 Madison Avenue, 20^th Floor

New York, New York 10022

Banks and Brokerage Firms, Please Call: (212) 750-5833

Stockholders and All Others Call Toll Free: (877) 750-0854

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SUMMARY

The following summary highlights selected information described in more detail elsewhere in this proxy statement/prospectus and the documents incorporated by reference into this proxy statement/prospectus and may not contain all the information that may be important to you. To understand the Mergers and the matters being voted on by Six Flags Stockholders at the Six Flags Special Meeting more fully, and to obtain a more complete description of the legal terms of the Merger Agreement and the agreements related thereto, you should carefully read this entire document, including the annexes and the documents incorporated herein and to which Six Flags and Cedar Fair refer you. Each item in this summary includes a page reference directing you to a more complete description of that topic. See the section entitled “Where You Can Find More Information.”

Six Flags Entertainment Corporation

Six Flags Entertainment Corporation

1000 Ballpark Way, Suite 400

Arlington, Texas 76011

Telephone: (972) 595-5180

Six Flags Entertainment Corporation is an amusement park company with 27 parks across the United States, Mexico and Canada. For 63 years, Six Flags has entertained hundreds of millions of guests with world-class coasters, themed rides, thrilling water parks and unique attractions. Six Flags is committed to creating an inclusive environment that fully embraces the diversity of the Six Flags team members and guests. For more information, visit www.sixflags.com.

Six Flags Common Stock is listed for trading on the NYSE under the symbol “SIX.”

Additional information about Six Flags and its subsidiaries is included in documents incorporated by reference in this proxy statement/prospectus. See the section entitled “Where You Can Find More Information.”

Cedar Fair, L.P.

Charlotte, North Carolina 28217

Telephone: (419) 626-0830

Cedar Fair is an amusement-resort operator and is a publicly traded partnership headquartered in Sandusky, Ohio. Focused on its mission to make people happy by providing fun, immersive, and memorable experiences, Cedar Fair owns and operates 13 properties, consisting of 11 amusement parks, four separately gated outdoor water parks, and resort accommodations totaling more than 2,300 rooms and more than 600 luxury RV sites. Cedar Fair’s parks are located in Ohio, California, North Carolina, South Carolina, Virginia, Pennsylvania, Minnesota, Missouri, Michigan, Texas and Toronto, Ontario. For more information visit https://ir.cedarfair.com.

Cedar Fair Units are listed for trading on the NYSE under the symbol “FUN.”

Additional information about Cedar Fair and its subsidiaries is included in documents incorporated by reference in this proxy statement/prospectus. See the section entitled “Where You Can Find More Information.”

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CopperSteel HoldCo, Inc.

c/o Six Flags Entertainment Corporation

1000 Ballpark Way, Suite 400

Arlington, Texas 76011

Telephone: (972) 595-5180

with a copy to:

Cedar Fair, L.P.

8701 Red Oak Blvd.

Charlotte, North Carolina 28217

Telephone: (419) 626-0830

CopperSteel is a Delaware corporation that is jointly owned by Six Flags and Cedar Fair and was formed on October 24, 2023 for the purpose of effecting the Mergers. To date, CopperSteel has not conducted any activities other than those incidental to its formation and the matters contemplated by the Merger Agreement in connection with the Mergers. Upon consummation of the Mergers, Six Flags and Cedar Fair will each have been merged with and into CopperSteel, with CopperSteel as the parent entity and successor corporation to Six Flags and Cedar Fair. Upon Closing, CopperSteel will be headquartered in Charlotte, North Carolina, and is expected to change its name to “Six Flags Entertainment Corporation” and be listed on NYSE under the ticker symbol “FUN.”

CopperSteel Merger Sub, LLC

CopperSteel Merger Sub, LLC

c/o Six Flags Entertainment Corporation

1000 Ballpark Way, Suite 400

Arlington, Texas 76011

Telephone: (972) 595-5180

with a copy to:

Cedar Fair, L.P.

8701 Red Oak Blvd.

Charlotte, North Carolina 28217

Telephone: (419) 626-0830

Copper Merger Sub is a Delaware limited liability company and wholly owned subsidiary of CopperSteel that was formed on October 24, 2023 for the purpose of effecting the Mergers. To date, Copper Merger Sub has not conducted any activities other than those incidental to its formation and the matters contemplated by the Merger Agreement in connection with the Mergers. Pursuant to the Merger Agreement, Copper Merger Sub will be merged with and into Cedar Fair, with Cedar Fair surviving the Cedar Fair First Merger as a subsidiary of CopperSteel.

The Mergers and the Merger Agreement

A copy of the Merger Agreement is attached as Annex A to this proxy statement/prospectus. Six Flags and Cedar Fair encourage you to read the entire Merger Agreement carefully because it is the principal document governing the Mergers. For more information on the Merger Agreement, see the section entitled “The Merger Agreement.”

Structure of the Mergers

The Merger Agreement provides that, among other things, upon the terms and subject to the conditions set forth in the Merger Agreement, (i) Copper Merger Sub, a wholly owned subsidiary of CopperSteel, will merge with

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and into Cedar Fair, with Cedar Fair continuing as the surviving entity of such merger as a direct subsidiary of CopperSteel, (ii) the Cedar Fair Surviving Entity will merge with and into CopperSteel, with CopperSteel continuing as the surviving corporation of such merger and (iii) Six Flags will merge with and into CopperSteel with CopperSteel continuing as the surviving corporation. Because the transaction is a merger of equals, CopperSteel will acquire Cedar Fair and Six Flags (as opposed to either of those parties acquiring the other party). Following the applicable Merger, the separate legal existences of Copper Merger Sub, Cedar Fair, and Six Flags will cease.

The organization of each of CopperSteel, Copper Merger Sub, Six Flags and Cedar Fair before and after the Mergers is illustrated on the following pages:

Prior to the Mergers

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The Cedar Fair First Merger

The Cedar Fair Second Merger

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The Six Flags Merger

Final Structure

The Six Flags Special Meeting of Stockholders

Six Flags has agreed to take all action necessary in accordance with applicable laws and the organizational documents of Six Flags to duly give notice of, convene and hold a meeting of the Six Flags Stockholders for the purpose of obtaining the approval of the Merger Agreement Proposal by the Six Flags Stockholders, to be held as promptly as practicable after the clearance of this proxy statement/prospectus by the SEC and a registration statement, of which this proxy statement/prospectus forms a part, being declared effective by the SEC. Unless there has been a Six Flags Recommendation Change in accordance with the Merger Agreement, the Six Flags Board must recommend that the Six Flags Stockholders vote in favor of the Merger Agreement Proposal, and this proxy statement/prospectus is required to include such recommendation of the Six Flags Board.

Six Flags may only postpone or adjourn the Six Flags Special Meeting (i) to solicit additional proxies for the purpose of obtaining the required Six Flags Stockholder Approval, (ii) for the absence of a quorum, and (iii) to

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allow reasonable additional time for the filing or mailing of any supplemental or amended disclosure that Six Flags has determined after consultation with outside legal counsel is reasonably likely to be required under applicable law and for such supplemental or amended disclosure to be disseminated and reviewed by Six Flags Stockholders prior to the Six Flags Special Meeting. Notwithstanding the foregoing, Six Flags shall postpone or adjourn the Six Flags Special Meeting up to two times for up to 30 days each time upon the mutual decision of Six Flags and Cedar Fair, each acting reasonably.

What Stockholders and Unitholders Will Receive in the Mergers and Potential Adjustments

Six Flags Merger Consideration. Subject to the terms and conditions set forth in the Merger Agreement, each Eligible Share outstanding immediately prior to the Closing Effective Time will be converted automatically into the right to receive 0.5800 shares of CopperSteel Common Stock, as may be adjusted pursuant to the Merger Agreement. Six Flags Stockholders will not receive any fractional shares of CopperSteel Common Stock in the Mergers. Instead, Six Flags Stockholders will receive cash in lieu of any fractional shares of CopperSteel Common Stock that they would otherwise have been entitled to receive.

Cedar Fair Merger Consideration. Subject to the terms and conditions set forth in the Merger Agreement, each Cedar Fair Unit issued and outstanding immediately prior to the Cedar Fair First Merger Effective Time (excluding (a) units held in the treasury of Cedar Fair or owned by the Cedar Fair General Partner and (b) any Cedar Fair Restricted Units) will be converted into the right to receive one (1) share of CopperSteel Common Stock, as may be adjusted subject to the terms and conditions set forth in the Merger Agreement. Cedar Fair Unitholders will not receive any fractional shares of CopperSteel Common Stock in the Mergers. Instead, Cedar Fair Unitholders will receive cash in lieu of any fractional shares of CopperSteel Common Stock that they would otherwise have been entitled to receive.

The Merger Agreement contains provisions that, in the event the outstanding Cedar Fair Units or shares of Six Flags Common Stock are, prior to the Closing, changed into a different number of units or shares, as applicable, by reason of any reclassification, recapitalization, split-up, combination, exchange of units or shares, dividend payable in stock or other securities or other similar transaction, the Cedar Fair Merger Consideration or the Six Flags Merger Consideration and the Cedar Fair Exchange Ratio or Six Flags Exchange Ratio or the amount of the Special Dividend will be adjusted to provide the holders of Cedar Fair Units, Six Flags Common Stock, Cedar Fair Equity Awards and Six Flags Equity Awards the same economic effect contemplated by the Merger Agreement prior to any such transaction, and in any event to ensure that the Cedar Fair Merger Consideration amounts to the aggregate number of shares of CopperSteel Common Stock representing at least 51.01% of the voting power of all issued and outstanding shares of CopperSteel Common Stock immediately following the Closing Effective Time.

The high and low trading prices for the Six Flags Common Stock as of November 2, 2023, the last trading day immediately before the public announcement of the Mergers, were $22.70 and $20.62, respectively. The high and low trading prices for the Cedar Fair Units as of November 2, 2023, the last trading day immediately before the public announcement of the Mergers, were $38.22 and $34.53, respectively. We urge you to obtain current market quotations before voting your shares.

Special Dividend

In connection with the Mergers and contingent upon the consummation thereof, on the date that is one business day prior to the Closing Date, Six Flags will, subject to applicable law and the organizational documents of Six Flags, declare the Special Dividend, payable to holders of record of Six Flags Common Stock as of the close of business one business day prior to the Closing Date, with a per share amount equal to:

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Treatment of Six Flags Equity Awards in the Mergers

At the Closing Effective Time, each outstanding Six Flags Equity Award will be converted into an equity award relating to shares of CopperSteel Common Stock, with the number of shares of CopperSteel Common Stock subject to such converted award calculated based on the Six Flags Exchange Ratio. Each converted Six Flags Equity Award will remain outstanding and subject to the same terms and conditions as applied to the corresponding Six Flags Equity Award immediately prior to the Closing Effective Time (except that (i) performance-based awards will convert based on the greater of target and actual performance and will not be subject to future performance-based vesting conditions (but will remain subject to service-based vesting conditions) and (ii) all converted awards will be subject to vesting protections for qualifying terminations that occur within a period of 24 months following the Closing). Any outstanding Six Flags Deferred Share Unit Awards will be settled at the Closing Effective Time in shares of CopperSteel Common Stock based on the Six Flags Exchange Ratio. Each Six Flags Equity Award will be eligible for payment of the Special Dividend, which will be paid at the same time as the underlying Six Flags Equity Award, as converted, becomes vested or settled pursuant to its terms.

For additional information on the treatment of Six Flags Equity Awards, please see the section entitled “The Merger Agreement — Treatment of Six Flags Equity Awards in the Mergers”, and for additional information on the differing treatment of Six Flags RSU Awards and Six Flags PSU Awards held by Messrs. Bassoul and Mick (the two Six Flags executive officers), see the section entitled “The Mergers — Interests of Certain Six Flags Directors and Executive Officers in the Mergers — Treatment of Six Flags Equity Awards Held by Six Flags Executive Officers.”

Treatment of Cedar Fair Equity Awards in the Mergers

At the Cedar Fair First Merger Effective Time, each outstanding Cedar Fair Equity Award (other than Cedar Fair Unit-Settled Deferred Units and Cedar Fair Cash-Settled Deferred Units held by non-employee members of the Cedar Fair Board) will be converted into an equity award relating to shares of CopperSteel Common Stock, with the number of shares of CopperSteel Common Stock subject to such converted award calculated based on the Cedar Fair Exchange Ratio. Each converted Cedar Fair Equity Award will remain outstanding and subject to the same terms and conditions as applied to the corresponding Cedar Fair Equity Award immediately prior to the Cedar Fair First Merger Effective Time, including vesting protections for qualifying terminations that occur within a period of 24 months following the Closing, except that (i) performance-based awards that are subject to a performance period (or portion thereof) in which the Closing Effective Time occurs will convert based on the higher of target performance and actual performance through the Cedar Fair First Merger Effective Time and will not be subject to future performance-based vesting conditions (but will remain subject to service-based vesting conditions) and (ii) performance-based awards that are subject to any performance period (or portion thereof) that begins after the Closing Effective Time will convert based on target performance and will not be subject to future performance-based vesting conditions (but will remain subject to service-based vesting conditions). Any outstanding Cedar Fair Unit-Settled Deferred Unit will be settled at the Cedar Fair First Merger Effective Time in shares of CopperSteel Common Stock based on the Cedar Fair Exchange Ratio. Any outstanding Cedar Fair Cash-Settled Deferred Unit will be settled at the Cedar Fair First Merger Effective Time in cash based on the number of Cedar Fair Units underlying the Cedar Fair Cash-Settled Deferred Unit and the closing price of a Cedar Fair Unit on the day immediately prior to the Closing Date.

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For additional information on the treatment of Cedar Fair Equity Awards, please see the section entitled “The Merger Agreement — Treatment of Cedar Fair Equity Awards in the Mergers.”

Ownership of CopperSteel Common Stock After the Mergers

Following the Closing Effective Time, Cedar Fair’s Unitholders will own approximately 51.2% of the outstanding shares of CopperSteel Common Stock and the Six Flags Stockholders will own approximately 48.8% of the outstanding shares of CopperSteel Common Stock.

Voting and Support Agreement

On November 2, 2023, Cedar Fair, H Partners, LP and certain of its affiliates (collectively, “H Partners”), and, solely for purposes of certain sections therein, Six Flags, entered into a Voting and Support Agreement (the “Voting and Support Agreement”), pursuant to which H Partners, a significant stockholder of Six Flags Common Stock which owned approximately 13.64% of the outstanding Six Flags Common Stock as of the date of the Merger Agreement, agreed to, among other things, and subject to certain exceptions, vote (or cause to be voted), in person or by proxy at the Six Flags Special Meeting, all shares of Six Flags Common Stock beneficially owned by H Partners as of the date of the Voting and Support Agreement (or thereafter acquired): (a) in favor of the Mergers and the adoption of the Merger Agreement and the transactions contemplated by the Merger Agreement, including any amended and restated merger agreement or amendment to the Merger Agreement that increases the Six Flags Merger Consideration, decreases the Cedar Fair Merger Consideration or otherwise is or results in the Merger Agreement being more favorable to H Partners than the Merger Agreement in effect as of the date of the Voting and Support Agreement; (b) in favor of the approval of any proposal to adjourn or postpone any Six Flags Special Meeting to a later date if there are not sufficient votes for adoption of the Merger Agreement on the date on which such Six Flags Special Meeting is held; (c) against any action or agreement that would reasonably be expected to result in a breach of any covenant, representation or warranty or any other obligation or agreement of Six Flags contained in the Merger Agreement; (d) against any action, proposal, transaction or agreement that would reasonably be expected to impede, materially delay or adversely affect the consummation of the Mergers or the fulfillment of Cedar Fair’s, Six Flags’ or Copper Merger Sub’s conditions under the Merger Agreement, any of the other transactions contemplated by the Merger Agreement or change in any manner the voting rights of any class of shares of Six Flags (including any amendments to Six Flags’ certificate of incorporation or bylaws); and (e) against any “Six Flags Alternative Transaction” (as defined in the section entitled “The Mergers — No Solicitation of Alternative Transactions”).

Opinion of Six Flags’ Financial Advisor

Goldman Sachs & Co. LLC (“Goldman Sachs”) delivered its opinion to the Six Flags Board that, as of November 2, 2023 and based upon and subject to the factors and assumptions set forth therein, and taking into account the Cedar Fair Mergers, the Six Flags Exchange Ratio and Special Dividend (the Six Flags Exchange Ratio together with the Special Dividend, the “Six Flags Aggregate Consideration”) to be paid to the holders (other than Cedar Fair and its affiliates) of Six Flags Common Stock pursuant to the Merger Agreement is fair from a financial point of view to such holders.

The full text of the written opinion of Goldman Sachs, dated November 2, 2023, which sets forth assumptions made, procedures followed, matters considered and limitations on the review undertaken in connection with the opinion, is attached as Annex B. Goldman Sachs provided advisory services and its opinion for the information and assistance of the Six Flags Board in connection with its consideration of the transactions contemplated by the Merger Agreement. Goldman Sachs’ opinion is not a recommendation as to how any holder of Six Flags Common Stock should vote with respect to the transactions contemplated by the Merger Agreement or any other matter. Pursuant to an engagement letter between Six Flags and Goldman Sachs, Six Flags has agreed to pay Goldman Sachs a transaction fee that is estimated, based on the information available as of the date of announcement, at approximately $60.3 million, $5 million of which became payable upon the announcement

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of the Merger Agreement, and the remainder of which is contingent upon consummation of the transactions contemplated thereby.

Recommendation of the Six Flags Board and Six Flags’ Reasons for the Merger

The Six Flags Board recommends that you vote “FOR” the Merger Agreement Proposal, “FOR” the Compensation Advisory Proposal and “FOR” the Adjournment Proposal. For a description of factors considered by the Six Flags Board in reaching its decision to approve the Merger Agreement and the transactions contemplated thereby, including the Mergers, and additional information on the recommendation of the Six Flags Board, see the section entitled “The Mergers — Recommendation of the Six Flags Board and Six Flags’ Reasons for the Mergers.”

Interests of Certain Six Flags Directors and Executive Officers in the Mergers

In considering the recommendation of the Six Flags Board that Six Flags Stockholders vote “FOR” the Merger Agreement Proposal, Six Flags Stockholders should be aware that, aside from their interests as Six Flags Stockholders, Six Flags’ directors and executive officers have interests in the Mergers that may be different from, or in addition to, the interests of Six Flags Stockholders generally, including, but not limited to, the treatment of outstanding Six Flags Equity Awards pursuant to the Merger Agreement, potential severance and other benefits upon a qualifying termination of employment in connection with the Mergers, eligibility, in the case of Mr. Bassoul, for a cash transaction bonus, eligibility for payment of an annual bonus in respect of 2023 and (depending on the timing of Closing) eligibility for payment of a pro-rated annual bonus in respect of 2024, and rights to ongoing indemnification and insurance coverage. These interests are described in more detail in the section entitled “The Mergers — Interests of Certain Six Flags Directors and Executive Officers in the Mergers.” The Six Flags Board was aware of and considered these potential interests, among other matters, in evaluating and negotiating the Merger Agreement and the transactions contemplated therein, in approving the Mergers and in recommending the adoption of the Merger Agreement Proposal. See the sections entitled “The Mergers — Background of the Mergers” and “The Mergers — Recommendation of the Six Flags Board and Six Flags’ Reasons for the Mergers.”

Board of Directors and Management of CopperSteel Following Completion of the Mergers

The Merger Agreement provides that the CopperSteel Board will initially consist of 12 directors, (i) six of whom will be persons designated by the Six Flags Board, divided evenly as Class I, Class II and Class III directors, from the directors of Six Flags serving prior to the Closing Effective Time, one of whom will be Mr. Selim A. Bassoul, current President and Chief Executive Officer of Six Flags, if he is the President and Chief Executive Officer of Six Flags immediately prior to the Closing Effective Time and one of whom will be Mr. Ben Baldanza, current Non-Executive Chairman of Six Flags, who will serve on the CopperSteel Board and Integration Committee, provided he remains on the Six Flags Board immediately prior to the Closing Effective Time, and (ii) six of whom will be persons designated by the Cedar Fair Board, divided evenly as Class I, Class II and Class III directors, from the directors of Cedar Fair serving prior to the Closing Effective Time, one of whom will be Mr. Richard A. Zimmerman, current President and Chief Executive Officer of Cedar Fair, if he is the President and Chief Executive Officer of Cedar Fair immediately prior to the Cedar Fair First Merger Effective Time, and one of whom will be Mr. Daniel J. Hanrahan, current Chairman of the Cedar Fair Board, who will serve as Lead Independent Director of the CopperSteel Board, provided he remains Chairman of the Cedar Fair Board immediately prior to the Cedar Fair First Merger Effective Time. Under the terms of the Merger Agreement, each of CopperSteel’s directors other than Messrs. Zimmerman and Bassoul must qualify as independent under the listing standards of the NYSE and the applicable rules of the SEC. Additionally, Chieh Huang, Enrique Ramirez Mena, Arik Ruchim, and Marilyn Spiegel have been designated by Six Flags and Louis Carr, Michelle Frymire, Jennifer Mason and D. Scott Olivet have been designated by Cedar Fair to serve on the CopperSteel Board. As of the date of this proxy statement/prospectus, the classification of each director has not been determined. As of the date of this proxy statement/prospectus, the terms of the director compensation that will be provided to the independent members of the CopperSteel Board have not been determined.

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Additionally, the Merger Agreement provides that, at the Closing Effective Time, (i) Mr. Zimmerman, current President and Chief Executive Officer of Cedar Fair, will serve as President and Chief Executive Officer of CopperSteel, (ii) Mr. Bassoul, current President and Chief Executive Officer of Six Flags, will serve as Executive Chairman of the CopperSteel Board, (iii) Mr. Gary Mick, current Chief Financial Officer of Six Flags, will serve as Chief Integration Officer of CopperSteel and (iv) Mr. Brian Witherow, current Chief Financial Officer of Cedar Fair, will serve as Chief Financial Officer of CopperSteel. Except as otherwise disclosed in this proxy statement/prospectus, the compensation of the post-Closing CopperSteel management team will be governed by their respective employment arrangements with Cedar Fair or Six Flags as in effect prior to Closing, unless or until such time as new employment arrangements with CopperSteel have been executed. Additionally, certain Six Flags or Cedar Fair executive officers may, prior to the consummation of the Mergers, enter into new employment agreements or arrangements or other retention arrangements with Six Flags, Cedar Fair and/or CopperSteel (as applicable), but the terms of such arrangements, if any, have not yet been finalized.

For additional discussion on the terms of the amended and restated employment agreements that each of Messrs. Bassoul and Mick will enter into with CopperSteel, please see the section entitled “The Mergers — Interests of Certain Six Flags Directors and Executive Officers in the Mergers — Agreements with Six Flags Executive Officers.”

Listing of CopperSteel Common Stock; Delisting and Deregistration of Six Flags Common Stock and Cedar Fair Units

Six Flags, with cooperation from Cedar Fair, shall use reasonable best efforts to have the shares of CopperSteel Common Stock issuable pursuant to the Mergers be approved for listing on the NYSE, subject to official notice of issuance as soon as practicable but in any case, prior to the Closing.

Shares of Six Flags Common Stock currently trade on the NYSE under the ticker symbol “SIX.” When the Mergers are completed, the Six Flags Common Stock will cease to be traded on the NYSE and will be deregistered under the Exchange Act.

Cedar Fair Units currently trade on the NYSE under the ticker symbol “FUN.” When the Mergers are completed, the Cedar Fair Units will cease to be traded on the NYSE and will be deregistered under the Exchange Act.

Prior to or upon consummation of the Mergers, the parties shall cause the name of CopperSteel to change to “Six Flags Entertainment Corporation” and the ticker symbol of CopperSteel, which shall be “FUN”, to be reserved for listing on the NYSE.

Appraisal Rights and Dissenters’ Rights

Six Flags

Under Delaware law, Six Flags Stockholders are entitled to appraisal rights under Section 262 of the DGCL with respect to the Merger Agreement Proposal, provided they satisfy the special criteria and conditions set forth in Section 262 of the DGCL. Six Flags Stockholders have no appraisal rights with respect to the Compensation Advisory Proposal. A copy of the text of the relevant provisions of Section 262 of the DGCL is attached to this proxy statement/prospectus as Annex E. Holders of Six Flags Common Stock are encouraged to read these provisions carefully and in their entirety. Moreover, due to the complexity of the procedures for exercising the right to seek appraisal, holders of Six Flags Common Stock who are considering exercising that right are encouraged to seek the advice of legal counsel. Failure to comply strictly with these provisions may result in the loss of the right of appraisal. For a more detailed description of Six Flags Stockholders’ dissenters’ or appraisal rights, see the section entitled “The Mergers — Appraisal Rights and Dissenters’ Rights.”

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Cedar Fair

Under Delaware law, as well as the governing documents of Cedar Fair, Cedar Fair Unitholders will not be entitled to any appraisal rights in connection with the Mergers or any other transactions described in this proxy statement/prospectus.

Regulatory Approvals

U.S. Antitrust Clearance

Closing is subject to antitrust review in the United States. Under the HSR Act, and the rules promulgated thereunder, the Mergers cannot be completed until the parties to the Merger Agreement have given notification and furnished information to the Federal Trade Commission (the “FTC”) and the United States Department of Justice (the “DOJ”), and until the applicable waiting period has expired or has been terminated.

On November 17, 2023 and November 20, 2023, the Premerger Notification Office of the Federal Trade Commission accepted the premerger notification and report forms under the HSR Act submitted by Six Flags and Cedar Fair, respectively. On December 20, 2023, Six Flags and Cedar Fair withdrew their respective premerger notification and report forms under the HSR Act and refiled them on December 21, 2023. On January 22, 2024, Six Flags and Cedar Fair each received a request for additional information and documentary materials (a “Second Request”) from the DOJ in connection with the DOJ’s review of the Mergers. The effect of a Second Request is to extend the waiting period imposed by the HSR Act, until 30 days after each of Six Flags and Cedar Fair has substantially complied with the Second Request issued to it, unless that period is extended voluntarily by the parties or terminated earlier by the DOJ. Per the terms of the Merger Agreement, Cedar Fair and Six Flags will use their reasonable best efforts to certify substantial compliance with the Second Request on or before May 2, 2024.

At any time before or after consummation of the Mergers, notwithstanding the expiration or termination of the waiting period applicable to the transactions contemplated by the Merger Agreement under the HSR Act, the FTC or the DOJ, or any state, could take such action under antitrust laws as it deems necessary or desirable in the public interest, including seeking to enjoin the completion of the Mergers or seeking the divestiture of substantial assets of Six Flags or Cedar Fair or their respective subsidiaries. Under certain circumstances, private parties may also seek to take legal action under antitrust laws.

Mexico Antitrust Clearance

Closing is subject to antitrust review in Mexico. The Mexican Federal Law on Economic Competition (“FLEC”) provides that, in the event a transaction meets certain thresholds designated by the FLEC, the constituent parties must file a joint pre-merger notification with the Mexican Federal Competition Commission (referred to in this proxy statement/prospectus as the “MFCC”). Six Flags’ four subsidiaries incorporated in Mexico gives the FLEC and MFCC jurisdiction to review the proposed transaction, and the Mergers and the transactions contemplated exceed the thresholds that merit review by the MFCC. Accordingly, as provided in the FLEC, the MFCC has jurisdiction to review the Mergers and the transactions contemplated by the Merger Agreement prior to Closing. On November 30, 2023 Six Flags and Cedar Fair submitted a pre-merger notification filing to the MFCC.

On January 25, 2024, the MFCC concluded its review of the transactions and determined to allow the transactions to proceed as proposed, subject to customary statutory requirements.

Securities and Exchange Commission

CopperSteel has filed a registration statement on Form S-4, of which this proxy statement/prospectus forms a part. Each of Six Flags, CopperSteel and Cedar Fair shall use reasonable best efforts to have the Form S-4

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declared effective under the Securities Act as promptly as practicable after such filing and to keep the Form S-4 effective so long as necessary to consummate the Mergers.

Regulatory Efforts

Under the Merger Agreement, each of Six Flags and Cedar Fair has agreed to use their respective reasonable best efforts, subject to certain limitations, to take, or cause to be taken, all actions, and to do, or cause to be done, and to assist and cooperate with the other parties in doing, all things necessary, proper or advisable to consummate and make effective, in the most expeditious manner practicable, the Mergers and the other transactions contemplated by the Merger Agreement. For more information, see the section entitled “The Merger Agreement — Covenants and Agreements — Efforts to Complete the Mergers.”

Conditions to Completion of the Mergers

The obligations of each of Six Flags and Cedar Fair to effect the Mergers are subject to the satisfaction or waiver, in whole or in part (to the extent permitted by applicable law), of the following conditions on or prior to the Closing Date:

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We cannot be certain when, or if, the conditions to the Mergers will be satisfied or waived, or that the Mergers will be completed.

Description of Debt Financing

Six Flags, Cedar Fair and CopperSteel have entered into an amended and restated debt commitment letter, dated as of December 5, 2023 (the “Debt Commitment Letter”), with Goldman Sachs Bank USA (“Goldman”) and certain other additional arrangers party thereto (the “Arrangers”), pursuant to which the Arrangers have committed to provide a senior secured revolving credit facility consisting of revolving credit commitments in an aggregate amount of $850 million (the “Debt Financing”) in connection with the Mergers. The Debt Commitment Letter amends, restates and supersedes that certain commitment letter, dated November 2, 2023, which provided revolving credit commitments in an aggregate amount of $800 million. The proceeds from the Debt Financing may be used to, among other things, pay for transaction costs in connection with the Mergers. The obligation of the Arrangers to provide the Debt Financing under the Debt Commitment Letter is subject to a number of conditions, including the receipt of executed loan documentation, accuracy of certain representations and warranties and the consummation of the transactions contemplated by the Merger Agreement.

In connection with the Mergers, Cedar Fair commenced consent solicitations on November 3, 2023 (the “Consent Solicitation”) from holders of its 5.375% Senior Notes due 2027, 5.250% Senior Notes due 2029, 5.500% Senior Secured Notes due 2025 and 6.500% Senior Notes due 2028 (collectively, the “Cedar Fair Bonds”) to amend certain provisions of the indentures governing the Cedar Fair Bonds (the “Indentures” and such amendments, the “Amendments”) to enable Cedar Fair and other co-issuers of the Cedar Fair Bonds to select November 2, 2023, the date the Merger Agreement was entered into, as the testing date for purposes of calculating, with respect to the Mergers and related transactions, any and all ratio tests under the Indentures. The Amendments will not, however, become operative with respect to any such series of Cedar Fair Bonds until an aggregate cash payment (the “Consent Payment”) for the benefit of certain holders of the Cedar Fair Bonds has been paid by Cedar Fair and other co-issuers of the Cedar Fair Bonds, which is expected to occur (if at all) upon or immediately prior to consummation of the Mergers. At the signing of the Merger Agreement, Goldman had committed to provide a senior secured 364-day term loan in an aggregate principal amount of $2,300 million (the “364-Day Term Facility”), the proceeds of which would be used to redeem any outstanding Cedar Fair Bonds that were not amended pursuant to the Consent Solicitation, to the extent not otherwise redeemed by Cedar Fair. On November 9, 2023, the requisite consents from holders of the Cedar Fair Bonds were obtained pursuant to the Consent Solicitation to effect the Amendments to the Indentures. As a result, the commitments in respect of the 364-Day Term Facility were automatically and permanently reduced to $0.

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Six Flags and Cedar Fair Expect the Mergers to be Completed in First Half of 2024

Six Flags and Cedar Fair intend to complete the Mergers as soon as reasonably practicable and are currently targeting completion of the Mergers during the first half of 2024. However, the Mergers are subject to regulatory approvals and clearances and other conditions, and it is possible that factors outside the control of both Six Flags and Cedar Fair could result in the Mergers being completed at a later time, or not at all. There may be a substantial amount of time between the Six Flags Special Meeting and the completion of the Mergers. For additional information on the regulatory approvals and clearances required to complete the Mergers, see the section entitled “The Mergers — Regulatory Approvals.”

No Solicitation of Alternative Transactions

Each of Six Flags and Cedar Fair have agreed not to, and not to authorize or permit any of its affiliates or any of its or their officers, directors or employees to, and to use its reasonable best efforts to cause any investment banker, financial advisor, attorney, accountant or other representative retained by it or its controlled affiliates not to, directly or indirectly, (i) solicit, initiate or knowingly encourage (including by way of furnishing information), or take any other action designed to facilitate, any inquiries regarding, or the making of, any proposal the consummation of which would constitute a “Six Flags Alternative Transaction” and “Cedar Fair Alternative Transaction” each as defined in the section entitled “The Mergers — No Solicitation of Alternative Transactions” or (ii) participate in any discussions or negotiations, or cooperate in any way with any person (or group of persons), with respect to any inquiries regarding, or the making of, any proposal the consummation of which would constitute an Alternative Transaction (as defined in the section entitled “The Mergers — No Solicitation of Alternative Transactions”).

Notwithstanding these restrictions, the Merger Agreement provides that, if at any time prior to obtaining the Six Flags Stockholder Approval, Six Flags receives a proposal that the Six Flags Board determines in good faith (after consultation with outside counsel and a financial advisor of nationally recognized reputation) constitutes or is reasonably likely to lead to a Six Flags Superior Proposal (as defined in the section entitled “The Mergers — No Solicitation of Alternative Transactions”) and which did not result from a material breach of the non-solicitation obligations set forth in the Merger Agreement, then Six Flags, may (i) furnish information with respect to itself and its subsidiaries to the person (or group of persons) making such proposal and its representatives and financing sources pursuant to a customary confidentiality agreement containing terms as to confidentiality generally no less restrictive than the terms of the confidentiality agreement entered into between Cedar Fair and Six Flags (provided that (x) such information must have been previously provided to Cedar Fair or must be provided to Cedar Fair prior to or substantially concurrently with the time it is provided to such person and (y) such confidentiality agreement need not contain any “standstill” term) and (ii) participate in discussions or negotiations regarding such proposal with the person (or group of persons) making such proposal and its representatives and financing sources.

Each of Six Flags and Cedar Fair have also agreed to promptly notify the other party orally and in writing, and in any event within 24 hours of receipt of any request for information or of any proposal relating to an Alternative Transaction, the material terms and conditions of such request or proposal (including any changes thereto) and the identity of the person making such request or proposal and provide the other party, as soon as reasonably practicable following delivery and receipt, copies of all correspondence and other written materials exchanged with the person making the proposal. Six Flags has also agreed to keep Cedar Fair reasonably informed of the status and details (including amendments or proposed amendments) of any such request or proposal on a reasonably current basis.

Changes in Six Flags Board Recommendation

Six Flags has agreed under the Merger Agreement to, through the Six Flags Board, recommend to its stockholders the Merger Agreement Proposal and to include such recommendation in this proxy statement/prospectus.

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The Merger Agreement provides that, subject to the exceptions described below, neither the Six Flags Board nor any committee thereof will (i) not effect a Six Flags Recommendation Change or (ii) cause Six Flags or any of its controlled affiliates to enter into any letter of intent, agreement in principle, acquisition agreement or other agreement related to any Six Flags Alternative Transaction or requiring, or reasonably likely to cause, Six Flags to terminate, delay or fail to consummate, or that would otherwise impede, interfere in any way with or be inconsistent with, the consummation of the Mergers or any of the other transactions contemplated by the Merger Agreement (other than a confidentiality agreement otherwise permitted by the Merger Agreement).

Notwithstanding the foregoing restrictions, at any time prior to obtaining the Six Flags Stockholder Approval, the Six Flags Board may, if it determines in good faith, after it has received a Six Flags Superior Proposal (and after consultation with outside counsel and a financial advisor of nationally recognized reputation and taking into account all factors and matters deemed relevant in good faith by the Six Flags Board) that the failure to take such action would be reasonably likely to be inconsistent with its fiduciary duties under applicable law, effect a Six Flags Recommendation Change. However, the Six Flags Board may not effect a Six Flags Recommendation Change in response to any Six Flags Superior Proposal unless it has given Cedar Fair at least four business days written notice specifying the material terms and conditions of such Six Flags Superior Proposal, identifying the person making such proposal and stating that it intends to make a Six Flags Recommendation Change, or in the event of a subsequent modification to the material terms and conditions of such Six Flags Superior Proposal, at least three business days written notice advising Cedar Fair of the modification to such terms and conditions; provided that during such four or three business day notice period, as applicable, Six Flags engages (to the extent requested by Cedar Fair) in good faith negotiations with Cedar Fair to amend the Merger Agreement in such a manner that the proposal to enter into an Six Flags Alternative Transaction no longer constitutes a Six Flags Superior Proposal.

In addition, at any time prior to obtaining the Six Flags Stockholder Approval, the Six Flags Board, may, if it determines in good faith (after consultation with outside counsel and a financial advisor of nationally recognized reputation) that the failure to do so would be reasonably likely to be inconsistent with its fiduciary duties under applicable law, effect a Six Flags Recommendation Change in response to any Six Flags Intervening Event (provided that (i) in no event will the receipt, existence or terms of a Six Flags Alternative Transaction or any matter relating thereto or consequence thereof constitute a Six Flags Intervening Event and (ii) in no event will any adverse effect of any event or events on the business, properties, financial condition or results of operations of Cedar Fair and its subsidiaries, taken as a whole, constitute a Six Flags Intervening Event unless such event has or would reasonably be expected to have a “Material Adverse Effect”). However, the Six Flags Board may not effect a Six Flags Recommendation Change in response to any Six Flags Intervening Event unless it has given Cedar Fair at least four business days written notice advising Cedar Fair of all material information with respect to any such Six Flags Intervening Event and stating that it intends to make a Six Flags Recommendation Change and providing its rationale therefor.

Termination of the Merger Agreement

The Merger Agreement may be terminated at any time prior to the Closing Effective Time, whether before or after receipt of the Six Flags Stockholder Approval, under the following circumstances:

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Expenses and Termination Fees Relating to the Mergers

Generally, each party is required to pay all fees and expenses incurred by it in connection with the Mergers and the other transactions and agreements contemplated by the Merger Agreement, except that each of Six Flags and Cedar Fair will bear and pay one-half of (i) the costs and expenses (other than the fees and expenses of each party’s attorneys and accountants, which will be borne by the party incurring such expenses) incurred by Six Flags and Cedar Fair in connection with the filings of the premerger notification and report forms under the HSR Act and similar laws of other jurisdictions and (ii) the fees and expenses incurred in connection with the preparation of the registration statement on Form S-4 of which this proxy statement/prospectus is a part (including any amendments and supplements thereto), its filing with the SEC and the mailing of this proxy statement/prospectus to Six Flags Stockholders and Cedar Fair Unitholders.

However, the Merger Agreement provides that, upon termination of the Merger Agreement under certain circumstances, Six Flags may be obligated to pay Cedar Fair a termination fee of $63.2 million. See the section entitled “The Merger Agreement — Expenses and Termination Fees” for a more complete discussion of the circumstances under which termination fees will be required to be paid.

Accounting Treatment of the Mergers

The Mergers will be accounted for using the acquisition method of accounting in accordance with Financial Accounting Standards Codification Topic 805, Business Combinations (“ASC 805”). See the section entitled “Unaudited Pro Forma Condensed Combined Financial Information.”

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Comparison of Stockholder Rights Before and After the Mergers

Upon completion of the Mergers, Six Flags Stockholders, certain holders of Six Flags Equity Awards, Cedar Fair Unitholders and certain holders of Cedar Fair Equity Awards will receive shares of CopperSteel Common Stock. The rights of each such equityholder of Six Flags and Cedar Fair who become CopperSteel Stockholders will change upon receipt of shares of CopperSteel Common Stock, which shall be governed by the DGCL, the CopperSteel certificate of incorporation and the CopperSteel bylaws. The differences in the rights of each such equityholder of Six Flags and Cedar Fair receiving shares of CopperSteel Common Stock in the Mergers are described in detail in the section entitled “Comparison of Stockholder and Unitholder Rights Before and After the Mergers.”

Material U.S. Federal Income Tax Consequences of the Six Flags Merger to Six Flags U.S. holders and the Special Dividend to Six Flags U.S. holders and non-U.S. holders

Subject to the limitations and qualifications (including with respect to the Special Dividend) described in the section entitled “Material U.S. Federal Income Tax Consequences for Six Flags Holders” of this proxy statement/prospectus, in the opinion of Kirkland & Ellis LLP, for U.S. federal income tax purposes, the Six Flags Merger will qualify as a “reorganization” within the meaning of Section 368(a) of the Code and the Special Dividend will be treated as a distribution from Six Flags for U.S. federal income tax purposes.

Accordingly, as a result of the Six Flags Merger, Six Flags U.S. holders (as defined in the section entitled “Material U.S. Federal Income Tax Consequences for Six Flags Holders” of this proxy statement/prospectus) will not recognize gain or loss for U.S. federal income tax purposes in the Six Flags Merger (other than with respect to the receipt of cash in lieu of fractional shares).

Additionally, if the Special Dividend is treated as a distribution from Six Flags for U.S. federal income tax purposes, the Special Dividend will generally constitute a dividend for U.S. federal income tax purposes to the extent paid from Six Flags’ current or accumulated earnings and profits, as determined under U.S. federal income tax principles. If a distribution exceeds Six Flags’ current and accumulated earnings and profits, the excess generally will be treated first as a tax-free return of capital to the extent of a Six Flags U.S. holder’s or Six Flags non-U.S. holder’s adjusted tax basis in its shares of Six Flags Common Stock, and any remaining excess will be treated as gain from the sale of shares of Six Flags Common Stock. Subject to certain exceptions described in the section entitled “Material U.S. Federal Income Tax Consequences for Six Flags Holders” of this proxy statement/prospectus, dividends paid to a Six Flags non-U.S. holder generally will be subject to withholding of U.S. federal income tax at a 30% rate unless such Six Flags non-U.S. holder is eligible for a reduced rate of withholding tax under an applicable income tax treaty and provides proper certification of its eligibility for such reduced rate. Nevertheless, the U.S. federal income tax treatment of the Special Dividend is not free from doubt.

See the section entitled “Material U.S. Federal Income Tax Consequences for Six Flags Holders” of this proxy statement/prospectus for more information on the material U.S. federal income tax consequences of the Six Flags Merger and the Special Dividend, including potential alternative characterizations of the Special Dividend for U.S. federal income tax purposes. Six Flags Stockholders are strongly urged to consult with their tax advisors about the tax consequences of the Six Flags Merger and the Special Dividend to them, including the effects of U.S. federal, state and local, foreign and other tax laws.

Material U.S. Federal Income Tax Consequences of the Mergers to Cedar Fair

Subject to the limitations and qualifications described in the section entitled “Material U.S. Federal Income Tax Consequences for Cedar Fair Unitholders” of this proxy statement/prospectus, for U.S. federal income tax purposes, the Cedar Fair First Merger taken together with the Six Flags Merger will qualify as a transaction described in Section 351 of the Code.

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Accordingly, subject to such limitations and qualifications, Cedar Fair Unitholders will not recognize gain or loss on the exchange of Cedar Fair Units for CopperSteel Common Stock, except that gain may be recognized with respect to certain liabilities treated as assumed by CopperSteel and cash received in lieu of a fractional share of CopperSteel Common Stock. If a Cedar Fair Unitholder recognizes gain, a portion of this gain may be separately computed and taxed as ordinary income under Section 751 of the Code to the extent attributable to “unrealized receivables,” including depreciation recapture or to “inventory items” owned by Cedar Fair. Otherwise such gain recognized generally will be long-term capital gain, provided certain holding period and other requirements are met. In addition to the tax consequences described above, Cedar Fair non-U.S. holders (as defined in the section entitled “Material U.S. Federal Income Tax Consequences for Cedar Fair Unitholders” of this proxy statement/prospectus) will be subject to withholding under Section 1446(f) of the Code with respect to the CopperSteel Common Stock received.

For more information on the material U.S. federal income tax consequences of the Cedar Fair First Merger, see the section entitled “Material U.S. Federal Income Tax Consequences for Cedar Fair Unitholders” of this proxy statement/prospectus. Cedar Fair Unitholders are strongly urged to consult with their tax advisors about the tax consequences of the Cedar Fair First Merger to them, including the effects of U.S. federal, state and local, foreign and other tax laws.

Risk Factors

You should carefully consider all of the information contained in or incorporated by reference into this proxy statement/prospectus, including the specific risk factors in the section entitled “Risk Factors.”

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SUMMARY UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL DATA

The following summary unaudited pro forma condensed combined balance sheet data gives effect to the merger as if it had occurred on September 24, 2023, while the unaudited pro forma condensed combined statement of operations data for the year ended December 31, 2022, and for the nine months ended September 24, 2023, are presented as if the merger occurred on January 1, 2022. This summary unaudited pro forma condensed combined financial information has been prepared for illustrative purposes only and are not necessarily indicative of what the combined company’s financial position or results of operations actually would have been had the merger occurred as of the date indicated. In addition, the unaudited pro forma condensed combined financial information does not purport to project the future financial position or operating results of the combined company. Future results may vary significantly from the results reflected because of various factors, including those discussed in the section entitled “Risk Factors”. The following summary unaudited pro forma condensed combined financial data should be read in conjunction with the section entitled “Unaudited Pro Forma Condensed Combined Financial Information” and the related notes.

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CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS

This proxy statement/prospectus, and the documents to which Six Flags and Cedar Fair refer you within this proxy statement/prospectus, as well as oral statements made or to be made by Six Flags and Cedar Fair, include “forward-looking statements” within the meaning of Section 27A of the Securities Act, Section 21E of the Exchange Act, and the United States Private Securities Litigation Reform Act of 1995, as amended. All statements, other than statements of historical fact, included in this proxy statement/prospectus, including those that address activities, events, or developments that Six Flags or Cedar Fair expects, believes, or anticipates will or may occur in the future, are forward-looking statements. Forward-looking statements include, but are not limited to, statements regarding the Mergers, the expected timetable for completing the Mergers, the results, effects, benefits and synergies of the Mergers, pro forma descriptions of the CopperSteel and its operations, integration and transition plans, synergies, opportunities, and anticipated future performance and any other statements regarding Six Flags’ or Cedar Fair’s respective future expectations, beliefs, plans, objectives, financial conditions, assumptions, or future events or performance that are not historical facts. Words such as “anticipate,” “believe,” “create,” “expect,” “future,” “guidance,” “intend,” “plan,” “potential,” “seek,” “synergies,” “target,” “will,” “would” and other similar expressions or the negative of such terms or other variations thereof and words and terms of similar substance used in connection with any discussion of future plans, actions, or events identify forward-looking statements. However, the absence of these words does not mean that the statements are not forward-looking.

Six Flags and Cedar Fair caution investors that any forward-looking statements are subject to known and unknown risks and uncertainties, many of which are outside Six Flags’ and Cedar Fair’s control, and which may cause actual results and future trends to differ materially from those matters expressed in, or implied or projected by, such forward-looking statements, which speak only as of the date of this proxy statement/prospectus. Investors are cautioned not to place undue reliance on these forward-looking statements. Risks and uncertainties that could cause actual results to differ from those described in forward-looking statements include the following:

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The foregoing list of factors is not exhaustive. For further discussion of these and other risks, contingencies, and uncertainties applicable to Six Flags and Cedar Fair, please see the section entitled “Risk Factors” in this proxy statement/prospectus as well as Six Flags’ and Cedar Fair’s other filings with the SEC incorporated herein by reference. Please see the section entitled “Where You Can Find More Information” for more information about the SEC filings incorporated by reference into this proxy statement/prospectus.

All subsequent written or oral forward-looking statements attributable to Six Flags, Cedar Fair or any person acting on its or their behalf are expressly qualified in their entirety by the cautionary statements contained in this

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section. All forward-looking statements speak only as of the date they are made and are based on information available at that time. Neither Six Flags nor Cedar Fair assumes any obligation to update forward-looking statements to reflect circumstances or events that occur after the date the forward-looking statements were made or to reflect the occurrence of unanticipated events except as required by federal securities laws. As forward-looking statements involve significant risks and uncertainties, caution should be exercised against placing undue reliance on such statements.

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RISK FACTORS

In addition to the other information contained in or incorporated by reference into this proxy statement/prospectus, including the matters addressed in the section entitled “Cautionary Statement Regarding Forward-Looking Statements,” the following risk factors should be considered carefully in determining whether to vote for the adoption of the Merger Agreement. You should also read and consider the risk factors associated with each of the businesses of Six Flags and Cedar Fair because these risk factors may affect the operations and financial results of the combined company. These risk factors may be found under Part I, Item 1A, “Risk Factors” in each of Six Flags’ and Cedar Fair’s Annual Reports on Form 10-K for the year ended December 31, 2022 filed with the SEC on March 7, 2023 and February 17, 2023, respectively, and in Six Flags’ and Cedar Fair’s subsequent filings with the SEC, in each case, which are incorporated by reference into this proxy statement/prospectus. For information on where you can obtain copies of this information, see the section entitled “Where You Can Find More Information.”

Risk Factors Relating to the Mergers

Because the Six Flags Exchange Ratio and the Cedar Fair Exchange Ratio are fixed, the number of shares of CopperSteel Common Stock to be received by Six Flags Stockholders and Cedar Fair Unitholders and to which holders of Six Flags Equity Awards and Cedar Fair Equity Awards would be entitled in connection with the Mergers will not change between now and the time the Mergers are completed to reflect changes in the trading price of Six Flags Common Stock or the Cedar Fair Units.

In connection with the Mergers, each Eligible Share will be converted automatically into the right to receive the Six Flags Merger Consideration and each outstanding Cedar Fair Unit (excluding (a) units held in the treasury of Cedar Fair or owned by the Cedar Fair General Partner and (b) any Cedar Fair Restricted Unit) will be converted automatically into the right to receive the Cedar Fair Merger Consideration, in each case with cash paid in lieu of the issuance of any fractional shares of CopperSteel Common Stock. The Six Flags Exchange Ratio and the Cedar Fair Exchange Ratio are fixed, except as the Cedar Fair Exchange Ratio may be adjusted pursuant to the Merger Agreement, see “The Mergers — What Stockholders and Unitholders Will Receive in the Mergers and Potential Adjustments.” The value of the Cedar Fair Merger Consideration and the Six Flags Merger Consideration will depend on the market prices of the Six Flags Common Stock the Cedar Fair Units, as applicable, at the Closing Effective Time. The market prices of the Six Flags Common Stock and the Cedar Fair Units have fluctuated since the date of the announcement of the parties’ entry into the Merger Agreement and will continue to fluctuate from the date of this proxy statement/prospectus to the date of the Six Flags Special Meeting and the date the Mergers are completed. Accordingly, you should obtain current stock price quotations for Six Flags Common Stock and Cedar Fair Units traded on the NYSE (trading symbols “SIX” and “FUN”, respectively) before deciding how to vote or abstain from voting on any of the proposals described in this proxy statement/prospectus. Accordingly, at the time of the Six Flags Special Meeting, Six Flags Stockholders and Cedar Fair Unitholders will not know or be able to determine the market value of the Merger Consideration they would receive upon completion of the Mergers. Stock/unit price changes may result from a variety of factors, including, among others, general market and economic conditions, changes in Six Flags’ and Cedar Fair’s respective businesses, operations and prospects, market assessments of the likelihood that the Mergers will be completed, the timing of the Mergers, regulatory considerations and other factors. Many of these factors are beyond Six Flags’ and Cedar Fair’s control.

The market price for CopperSteel Common Stock following the Closing may be affected by factors different from those that historically have affected or currently affect Six Flags Common Stock and Cedar Fair Units.

Upon completion of the Mergers, Six Flags Stockholders, certain holders of Six Flags Equity Awards, certain holders of Cedar Fair Equity Awards, and Cedar Fair Unitholders will receive shares of CopperSteel Common Stock. CopperSteel’s financial position may differ from each of Six Flags’ and Cedar Fair’s financial positions before the completion of the Mergers, and the results of operations of CopperSteel may be affected by

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some factors that are different from those currently affecting the results of operations of each of Six Flags and Cedar Fair. Accordingly, the market price and performance of CopperSteel Common Stock is likely to be different from the performance of Six Flags Common Stock and Cedar Fair Units prior to Closing. In addition, general fluctuations in stock markets could have a Material Adverse Effect on the market for, or liquidity of, CopperSteel Common Stock, regardless of CopperSteel’s actual operating performance. For a discussion of the businesses of Six Flags and Cedar Fair, and important factors to consider in connection with those businesses, see the documents attached hereto or incorporated by reference and referred to in “Where You Can Find More Information.”

Six Flags Stockholders and Cedar Fair Unitholders as of immediately prior to the Mergers will have reduced ownership in CopperSteel.

Following the Closing, Six Flags’ existing stockholders are expected to own approximately 48.8% of the issued and outstanding shares of CopperSteel and Cedar Fair’s existing unitholders are expected to own approximately 51.2% of the issued and outstanding shares of CopperSteel, in each case on a fully diluted basis. As a result, existing Six Flags Stockholders and Cedar Fair Unitholders will have less influence on the policies of CopperSteel than they currently have on the policies of Six Flags or Cedar Fair, as applicable.

Regulatory approvals may not be received, may take longer than expected or may impose conditions that are not presently anticipated or cannot be met.

Before the Mergers can be completed, certain approvals must be obtained from antitrust regulatory agencies in the United States and Mexico. The terms of the approvals that are granted may impose antitrust related conditions, limitations, obligations or costs, or place restrictions on the conduct of Six Flags’ or Cedar Fair’s respective businesses or require changes to the terms of the Merger Agreement and the parties may not have an obligation to accept any such antitrust related condition, limitation, obligation or restriction. There can be no assurance that antitrust regulators will not impose any such antitrust related conditions, limitations, obligations or restrictions and that any such antitrust related conditions, limitations, obligations or restrictions will not have the effect of delaying the completion of any of the Mergers, imposing additional material costs on or otherwise reducing the anticipated benefits of the Mergers if the Mergers were consummated successfully within the expected timeframe. Nor can there be any assurance that any such antitrust related conditions, terms, obligations or restrictions will not result in the delay or abandonment of the Mergers. Additionally, the completion of the Mergers is conditioned on the absence of certain orders or injunctions issued by any court of competent jurisdiction or other legal restraints that would prohibit or make illegal the consummation of any of the transactions contemplated by the Merger Agreement.

Even if the Cedar Fair First Merger otherwise qualifies for tax-free treatment, a Cedar Fair Unitholder will recognize taxable gain upon the exchange of Cedar Fair Units in the Cedar Fair First Merger if and to the extent that (i) the aggregate amount of Cedar Fair liabilities attributable to the Cedar Fair Units exchanged by the Cedar Fair Unitholder exceeds (ii) the Cedar Fair Unitholder’s aggregate tax basis in the Cedar Fair Units exchanged by such Cedar Fair Unitholder.

As discussed in the section entitled “Material U.S. Federal Income Tax Consequences for Cedar Fair Unitholders” of this proxy statement/prospectus, under applicable U.S. federal income tax laws, it is intended that, for U.S. federal income tax purposes, the Cedar Fair First Merger taken together with the Six Flags Merger qualify as a transaction described in Section 351 of the Code in which no gain or loss is recognized. However, even if the Cedar Fair First Merger qualifies as a transaction described in Section 351 of the Code, under Section 357(c) of the Code, if a corporation assumes (or, is treated for U.S. federal income tax purposes as having assumed) liabilities of the transferor (or accepts property subject to liabilities) in an exchange described in Section 351 of the Code, the transferor generally must recognize taxable gain in the amount by which the liabilities exceed the transferor’s basis in the property contributed to the corporation. Under Section 752 of the

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Code, the liabilities of Cedar Fair are allocated to the Cedar Fair Unitholders and as a result of the Cedar Fair First Merger, the Cedar Fair liabilities allocated to the Cedar Fair Unitholders will be treated as having been assumed by CopperSteel and will be subject to Section 357(c) of the Code. Accordingly, a Cedar Fair Unitholder will recognize taxable gain upon the exchange of Cedar Fair Units in the Cedar Fair First Merger if and to the extent that (i) the aggregate amount of Cedar Fair liabilities attributable to the Cedar Fair Units exchanged by the Cedar Fair Unitholder exceeds (ii) the Cedar Fair Unitholder’s aggregate tax basis in the Cedar Fair Units exchanged by such Cedar Fair Unitholder. For more information on the material U.S. federal income tax consequences of the Cedar Fair First Merger, see the section entitled “Material U.S. Federal Income Tax Consequences for Cedar Fair Unitholders.”

Cedar Fair non-U.S. holders will be subject to withholding in the exchange of Cedar Fair Units for CopperSteel Common Stock in the Cedar Fair First Merger, and the applicable withholding agent may satisfy such withholding by retaining shares of CopperSteel Common Stock or cash or other property of the Cedar Fair non-U.S. holder.

As discussed in the section entitled “Material U.S. Federal Income Tax Consequences for Cedar Fair Unitholders” of this proxy statement/prospectus, Cedar Fair non-U.S. holders (as defined in the section entitled “Material U.S. Federal Income Tax Consequences for Cedar Fair Unitholders” of this proxy statement/prospectus) are taxed by the U.S. on effectively connected income (as defined in the section entitled “Material U.S. Federal Income Tax Consequences for Cedar Fair Unitholders” of this proxy statement/prospectus), unless exempted or further limited by an income tax treaty. Each Cedar Fair non-U.S. holder is considered to be engaged in business in the U.S. because of their ownership of Cedar Fair Units. Furthermore, it is probable that such Cedar Fair non-U.S. holders are deemed to conduct such activities through permanent establishments in the U.S. within the meaning of applicable tax treaties. Treasury Regulations under Section 1446(f) of the Code provide that the broker effecting the transfer of a Cedar Fair non-U.S. holders interest in a publicly traded partnership engaged in a U.S. trade or business, such as Cedar Fair, is required to withhold 10% of the amount realized, even if the exchange otherwise qualifies for nonrecognition treatment for U.S. federal income tax purposes. Cedar Fair non-U.S. holders should expect to have the applicable withholding agent withhold 10% of the gross proceeds received by the Cedar Fair non-U.S. holder, and the applicable withholding agent may satisfy such withholding by withholding shares of CopperSteel Common Stock or cash or other property of the Cedar Fair non-U.S. holder. For additional information regarding the U.S. federal income tax consequences of the Mergers, see the section entitled “Material U.S. Federal Income Tax Consequences for Cedar Fair Unitholders.”

The Amendments becoming operative and payment of the Consent Payment in connection with the Consent Solicitation with respect to the Cedar Fair Bonds may result in Cedar Fair Unitholders being allocated cancellation of debt income for U.S. federal income tax purposes.

In connection with the Consent Solicitation with respect to the Cedar Fair Bonds, the Amendments may become operative and certain holders of the Cedar Fair Bonds may receive the Consent Payment, see “The Mergers — Description of Debt Financing.”

As discussed in the section entitled “Material U.S. Federal Income Tax Consequences for Cedar Fair Unitholders” of this proxy statement/prospectus, payment of the Consent Payment in connection with the Consent Solicitation may result in a “significant modification” of one or more series of the Cedar Fair Bonds. If one or more series of the Cedar Fair Bonds were to undergo a significant modification, Cedar Fair may recognize CODI as a result of a deemed exchange of “old” Cedar Fair Bonds for “new” Cedar Fair Bonds, which would be allocated and taxable to the Cedar Fair Unitholders. Cedar Fair will not be able to calculate whether the payment of the Consent Payment will result in a significant modification or the amount of CODI (as defined in the section entitled “Material U.S. Federal Income Tax Consequences for Cedar Fair Unitholders” of this proxy statement/prospectus), if any, that would be allocated and taxable to the Cedar Fair Unitholders until the Consent Payment is paid, which is expected to occur (if at all) upon or immediately prior to consummation of the Mergers.

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Cedar Fair intends to take the position that the Amendments becoming operative for any series of Cedar Fair Bonds does not result in Cedar Fair recognizing CODI for U.S. federal income tax purposes. However, such position is not free from doubt.

For additional information regarding the U.S. federal income tax consequences of the payment of the Consent Payment and the Amendments becoming operative, see the section entitled “Material U.S. Federal Income Tax Consequences for Cedar Fair Unitholders.”

The Mergers are subject to a number of conditions to the obligations of both Six Flags and Cedar Fair to complete the Mergers, which, if not fulfilled, or not fulfilled in a timely manner, may delay completion of the Mergers or result in termination of the Merger Agreement.

The obligations of Six Flags and Cedar Fair to consummate the Mergers are subject to the satisfaction (or waiver by all parties, to the extent permissible under applicable laws) of the conditions described in “The Merger Agreement — Conditions to Completion of the Mergers.”

Many of the conditions to completion of the Mergers are not within either Six Flags’ or Cedar Fair’s respective control, and neither company can predict when, or if, these conditions will be satisfied. If any of these conditions are not satisfied or waived prior to the Outside Date, as such date may be extended pursuant to the terms of the Merger Agreement, it is possible that the Merger Agreement may be terminated. Although Six Flags and Cedar Fair have agreed in the Merger Agreement to use reasonable best efforts, subject to certain limitations, to complete the Mergers as promptly as practicable, these and other conditions to the completion of the Mergers may fail to be satisfied. In addition, satisfying the conditions to and completion of the Mergers may take longer, and could cost more, than Six Flags and Cedar Fair expect. Neither Six Flags nor Cedar Fair can predict whether and when these other conditions will be satisfied. Furthermore, the requirements for obtaining the required clearances and approvals could delay the completion of the Mergers for a significant period of time or prevent them from occurring. Any delay in completing the Mergers may adversely affect the cost savings and other benefits that Six Flags and Cedar Fair expect to achieve if the Mergers and the integration of the companies’ respective businesses are completed within the expected timeframe. There can be no assurance that all required regulatory approvals will be obtained or obtained prior to the Outside Date.

Uncertainties associated with the Mergers may cause a loss of management personnel and other key employees of Six Flags and Cedar Fair, which could adversely affect the future business and operations of CopperSteel following the Mergers.

The success of the Mergers will depend in part on Six Flags’ and Cedar Fair’s ability to retain management personnel and other key employees while the Mergers are pending and after Closing. Current and prospective employees of Six Flags and Cedar Fair may experience uncertainty about their roles within CopperSteel following the Mergers or other concerns regarding the timing and completion of the Mergers or the operations of CopperSteel following the Mergers, any of which may have an adverse effect on the ability of Six Flags and Cedar Fair to retain or attract management personnel and other key employees. If Six Flags and Cedar Fair are unable to retain key employees, Six Flags, Cedar Fair and, upon Closing, CopperSteel could face the loss of institutional knowledge and skill sets and other operational, financial and strategic disruptions, which may diminish the anticipated benefits of the Mergers and may have a negative impact on Six Flags or Cedar Fair during the pendency of the Mergers. No assurance can be given that CopperSteel, following the Mergers, will be able to retain or attract management personnel and other key employees to the same extent that Six Flags and Cedar Fair have previously been able to retain or attract their own employees.

The business relationships of Six Flags and Cedar Fair may be subject to disruption due to uncertainty associated with the Mergers, which could have a Material Adverse Effect on the results of operations, cash flows and financial position of Six Flags and Cedar Fair pending and following the Mergers.

Parties with which Six Flags and Cedar Fair do business may experience uncertainty associated with the Mergers, including with respect to current or future business relationships with Six Flags and Cedar Fair

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following the Mergers. Six Flags’ and Cedar Fair’s business relationships may be subject to disruption as suppliers, concessionaires, vendors and other third-party business partners may attempt to delay or defer entering into new business relationships, negotiate changes in existing business relationships or consider entering into business relationships with parties other than Six Flags and Cedar Fair following the Mergers. These disruptions could have a material and adverse effect on the results of operations, cash flows and financial position of Six Flags and Cedar Fair, regardless of whether the Mergers are completed, as well as a material and adverse effect on CopperSteel’s ability to realize the expected cost savings and other benefits of the Mergers. The risk, and adverse effect, of any disruption could be exacerbated by a delay in completion of the Mergers or termination of the Merger Agreement.

The Merger Agreement subjects Six Flags and Cedar Fair to restrictions on their respective business activities prior to the Closing.

The Merger Agreement subjects Six Flags and Cedar Fair to restrictions on their respective business activities prior to the Closing. The Merger Agreement obligates each of Six Flags and Cedar Fair to generally conduct its businesses in the ordinary course until the Closing Effective Time and to use its reasonable best efforts to (i) preserve intact their current business organizations, (ii) preserve their assets and properties in good repair and condition and (iii) keep available the services of their current officers and other key employees and preserve their relationships with those having business dealings with Six Flags and Cedar Fair. These restrictions could prevent Six Flags and Cedar Fair from pursuing certain business opportunities that arise prior to the Closing and are outside the ordinary course of business. See “The Merger Agreement — Covenants and Agreements” for additional details.

Six Flags directors and executive officers have interests in the Mergers that may be different from, or in addition to, the interests of the Six Flags Stockholders generally.

In considering the recommendation of the Six Flags Board with respect to the Merger Agreement, Six Flags Stockholders should be aware of and take into account the fact that certain Six Flags directors and executive officers have interests in the Mergers that may be different from, or in addition to, the interests of Six Flags Stockholders generally, including the treatment of outstanding Six Flags Equity Awards pursuant to the Merger Agreement, potential severance and other benefits upon a qualifying termination in connection with the Mergers, eligibility, in the case of Mr. Bassoul, for a cash transaction award and rights to ongoing indemnification and insurance coverage. These interests include, among others, rights to continuing indemnification and directors’ and officers’ liability insurance. See the section entitled “The Mergers — Interests of Certain Six Flags Directors and Executive Officers in the Mergers” for a more detailed description of these interests. The Six Flags Board was aware of and carefully considered these interests, among other matters, in evaluating the terms and structure, and overseeing the negotiation, of the Mergers, in approving the Merger Agreement and the transactions contemplated thereby, and in recommending that the Six Flags Stockholders adopt the Merger Agreement.

The Merger Agreement limits Six Flags’ and Cedar Fair’s respective ability to pursue alternative transaction proposals, which may discourage other companies from making a favorable alternative transaction proposal and, in specified circumstances, could require Six Flags to pay Cedar Fair a termination fee.

The Merger Agreement contains certain provisions that restrict each of Six Flags’ and Cedar Fair’s ability to solicit, initiate or knowingly encourage (including by way of furnishing information), or take any other action designed to facilitate, any inquiries or the making of competing alternative transaction proposals. Such competing alternative transaction proposals include proposals by third-parties involving, among other things (each, an “Alternative Transaction,” and with respect to Cedar Fair, a “Cedar Fair Alternative Transaction” and with respect to Six Flags a “Six Flags Alternative Transaction”): any transaction or series of transactions which result in the acquisition of more than 20% of the outstanding equity or voting power of Six Flags or Cedar Fair, as applicable; any merger, consolidation, share exchange or similar transaction resulting in the acquisition or, or acquisition of control over, assets or business representing 20% or more of the consolidated revenues, net income

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or assets of Six Flags or Cedar Fair, as applicable; and any transaction resulting in the disposition of assets representing 20% or more of the consolidated revenues, net income or assets of Six Flags or Cedar Fair, as applicable. Furthermore, under the terms of the Merger Agreement, the Six Flags Board is not permitted to (i) withdraw, qualify, modify or propose to take such actions, in a manner adverse to Cedar Fair, its recommendation with respect to the Merger Agreement Proposal or (ii) recommend or approve, or propose to take such actions, an Alternative Transaction proposal, subject to certain exceptions for actions taken in good faith in connection with a superior transaction proposal or intervening event to the extent necessary to satisfy its fiduciary duties under applicable law. See “The Merger Agreement — No Solicitation of Alternative Transactions; and – Changes in Six Flags Board Recommendation.”

Additionally, Six Flags and Cedar Fair are each subject to restrictions on their ability to participate in any discussions or negotiations, or cooperate with any third parties with respect to any inquiries regarding, or the making of, any proposal that would constitute an Alternative Transaction, subject, in the case of Six Flags, to certain exceptions under the Merger Agreement. The Merger Agreement further provides that, under specified circumstances, including after receipt of certain alternative acquisition proposals, Six Flags may be required to pay Cedar Fair a cash termination fee equal to $63.2 million. See “The Merger Agreement — No Solicitation of Alternative Transactions and – Expenses and Termination Fees” for additional details.

These provisions could discourage a potential third-party acquirer or other strategic transaction partner that might have an interest in acquiring all or a significant portion of Six Flags or Cedar Fair from considering or pursuing an Alternative Transaction with either party or proposing such a transaction, even if it were prepared, in Six Flags’ case, to pay consideration with a higher per share value than the total value proposed to be paid or received in the Mergers. These provisions might also result in a potential third-party acquirer or other strategic transaction partner proposing to pay a lower price than it might otherwise have proposed to pay because of the added expense of the termination fee that may become payable in certain circumstances.

Failure to complete the Mergers could negatively impact Six Flags’ or Cedar Fair’s respective stock prices and have a Material Adverse Effect on their results of operations, cash flows and financial position.

If the Mergers are not completed for any reason, including as a result of failure to obtain all requisite regulatory approvals or if the Six Flags Stockholders fail to approve the Merger Agreement Proposal, the ongoing businesses of Six Flags and Cedar Fair may be materially adversely affected and, without realizing any of the benefits of having completed the Mergers, Six Flags and Cedar Fair would be subject to a number of risks, including the following:

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If the Mergers are not completed, the risks described above may materialize and they may have a Material Adverse Effect on Six Flags’ or Cedar Fair’s respective results of operations, cash flows, financial position and stock prices.

The shares of CopperSteel Common Stock to be received by Six Flags Stockholders and Cedar Fair Unitholders upon completion of the Mergers will have different rights from shares of Six Flags Common Stock and Cedar Fair Units.

Upon completion of the Mergers, Six Flags Stockholders will no longer be Six Flags Stockholders and Cedar Fair Unitholders will no longer be Cedar Fair Unitholders. Instead, former Six Flags Stockholders and Cedar Fair Unitholders will become CopperSteel Stockholders and while their rights as CopperSteel Stockholders will continue to be governed by the laws of the state of Delaware, their rights will be subject to and governed by the terms of CopperSteel’s certificate of incorporation and CopperSteel’s bylaws. The terms of CopperSteel’s certificate of incorporation and CopperSteel’s bylaws are in some respects different than the terms of the Six Flags Certificate of Incorporation, the Six Flags Bylaws, and the Cedar Fair Limited Partnership Agreement, which currently govern the rights of Six Flags Stockholders and Cedar Fair Unitholders, respectively. See “Comparison of Stockholder and Unitholder Rights Before and After the Mergers” for a discussion of the different rights associated with shares of CopperSteel Common Stock, shares of Six Flags Common Stock and Cedar Fair Units.

Completion of the Mergers may trigger change in control or other provisions in certain agreements to which Six Flags or Cedar Fair is a party.

The completion of the Mergers may trigger change in control or other provisions in certain agreements to which Six Flags or Cedar Fair is a party. If Six Flags or Cedar Fair are unable to negotiate waivers of those provisions, the counterparties may exercise their rights and remedies under such agreements, potentially terminating such agreements, or seeking monetary damages. Even if Six Flags or Cedar Fair are able to negotiate waivers, the counterparties may require a fee for such waivers or seek to renegotiate such agreements on terms less favorable to Six Flags or Cedar Fair, as applicable, and upon Closing, CopperSteel.

Six Flags and Cedar Fair are expected to incur significant transaction costs in connection with the Mergers, which may be in excess of those anticipated by them.

Six Flags and Cedar Fair have incurred and are expected to continue to incur a number of non-recurring costs associated with negotiating and completing the Mergers, combining the operations of the two companies and achieving desired synergies. These costs have been, and will continue to be, substantial and, in many cases, will be borne by Six Flags and Cedar Fair whether or not the Mergers are completed. A substantial majority of non-recurring expenses will consist of transaction costs and include, among others, fees paid to financial, legal, accounting and other advisors, employee retention, severance and benefit costs, and filing fees. Six Flags and Cedar Fair will continue to assess the magnitude of these costs, and additional unanticipated costs may be incurred in connection with the Mergers and the integration of the two companies’ respective businesses. While Six Flags and Cedar Fair have assumed that a certain level of expenses would be incurred, there are many factors beyond their control that could affect the total amount or the timing of the expenses. The elimination of duplicative costs, as well as the realization of other efficiencies related to the integration of the respective businesses, may not offset integration-related costs and achieve a net benefit in the near term, or at all. The costs described above and any unanticipated costs and expenses, many of which will be borne by Six Flags and Cedar Fair even if the Mergers are not completed, could have an adverse effect on Six Flags’ or Cedar Fair’s respective financial conditions and operating results.

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The opinion of Six Flags’ financial advisor will not reflect changes in circumstances between the signing of the Merger Agreement and the completion of the Mergers.

Six Flags has received an opinion from its financial advisor in connection with the signing of the Merger Agreement but has not obtained any updated opinion from its financial advisor as of the date of this proxy statement/prospectus. Changes in the operations and prospects of Six Flags or Cedar Fair, general market and economic conditions and other factors that may be beyond the control of Six Flags or Cedar Fair, and on which the financial advisor’s opinion was based, may significantly alter the value of Six Flags or Cedar Fair or the prices of the shares of Six Flags Common Stock or Cedar Fair Units by the time the Mergers are completed. The opinion does not speak as of the time the Mergers will be completed or as of any date other than the date of such opinion. Because Six Flags does not currently anticipate asking its financial advisor to update its opinion, such opinion will not address the fairness of the Merger Consideration from a financial point of view at the time the Mergers are completed. The Six Flags Board’s recommendation that Six Flags Stockholders vote in favor of the Merger Agreement Proposal, however, is made as of the date of this proxy statement/prospectus.

Litigation relating to the Mergers could result in an injunction preventing the completion of the Mergers and/or substantial costs to Six Flags and Cedar Fair.

Securities class action lawsuits and derivative lawsuits are often brought against public companies that have entered into acquisition, merger or other business combination agreements. Even if such a lawsuit is without merit, defending against these claims can result in substantial costs and divert management time and resources. An adverse judgment could result in monetary damages, which could have a negative impact on Six Flags’ and Cedar Fair’s respective liquidity and financial condition.

Lawsuits that may be brought against Six Flags, Cedar Fair or their respective directors could also seek, among other things, injunctive relief or other equitable relief, including a request to rescind parts of the Merger Agreement already implemented and to otherwise enjoin the parties from consummating the Mergers. One of the conditions to the Closing is that no injunction by any federal, state, local, foreign or supranational government, any court, administrative, regulatory or other governmental agency, commission or authority or any non-governmental self-regulatory agency, commission or authority or any arbitral body (public or private) of competent jurisdiction has been entered and continues to be in effect. Consequently, if a plaintiff is successful in obtaining an injunction prohibiting completion of the Mergers, that injunction may delay or prevent the Mergers from being completed within the expected timeframe or at all, which may adversely affect Six Flags’ and Cedar Fair’s respective business, financial position and results of operation.

There can be no assurance that any of the defendants will be successful in the outcome of any pending or any potential future lawsuits. The defense or settlement of any lawsuit or claim that remains unresolved at the time the Mergers are completed may adversely affect Six Flags’ or Cedar Fair’s respective businesses, financial conditions, results of operations and cash flows.

Risk Factors Relating to CopperSteel Following the Mergers

CopperSteel may be unable to integrate the business of Six Flags and Cedar Fair successfully or realize the anticipated benefits of the Mergers.

The Mergers involve the combination of two companies that currently operate as independent public companies. The combination of two independent businesses is complex, costly and time consuming, and each of Six Flags and Cedar Fair will be required to devote significant management attention and resources to integrating the business practices and operations of Six Flags and Cedar Fair. Potential difficulties that Six Flags and Cedar Fair may encounter as part of the integration process include the following:

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In addition, Six Flags and Cedar Fair have operated and, until the completion of the Mergers, will continue to operate, independently. It is possible that the integration process could result in:

Any of these issues could adversely affect each company’s ability to maintain relationships with guests, employees, suppliers, concessionaires, vendors, other third-party business partners and other constituencies or achieve the anticipated benefits of the Mergers, or could reduce each company’s earnings or otherwise adversely affect the business and financial results of CopperSteel following the Mergers.

Although Six Flags and Cedar Fair expect that the Mergers will result in synergies and other benefits, those synergies and benefits may not be realized or may not be realized within the expected timeframe. CopperSteel may also encounter significant unexpected difficulties in integrating the two businesses.

Six Flags and Cedar Fair believe there are significant benefits and synergies that may be realized through leveraging the workforce, scale and guest engagement of Six Flags and Cedar Fair. However, the efforts to realize these benefits and synergies will be a complex process and may disrupt both companies’ existing operations if not implemented in a timely and efficient manner. The ability of Six Flags and Cedar Fair to realize the anticipated benefits of the Mergers will depend, to a large extent, on CopperSteel’s ability to integrate Six Flags’ and Cedar Fair’s businesses in a manner that facilitates growth opportunities and achieves projected cost savings and growth without adversely affecting current revenues and investments in future growth. Six Flags and Cedar Fair will be required to devote significant attention and resources prior to Closing to begin transitioning their operations to CopperSteel and prepare for the post-Closing integration process. Following the Closing, CopperSteel will need to devote significant attention and resources to successfully align the prior business practices and operations of Six Flags and Cedar Fair. This process may disrupt the businesses and, if implemented ineffectively, would limit or preclude the realization of the full benefits of the Mergers expected by Six Flags and Cedar Fair. CopperSteel’s failure to meet the challenges involved in integrating the two businesses to realize the anticipated benefits of the Mergers could cause an interruption of, or a loss of momentum in, the activities of CopperSteel and could adversely affect CopperSteel’s results of operation.

In addition, the overall integration of the businesses may result in material unanticipated problems, expenses, liabilities, responses from numerous out-of-home entertainment competitors, loss of guest relationships, and diversion of management’s attention. The difficulties of combining the operations of the companies include, among others:

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Many of these factors will be outside of CopperSteel’s control and any of them could result in increased costs, decreases in the amount of expected revenues and diversion of management’s time and energy, which could materially impact the business, financial condition and results of operations of CopperSteel. In addition, even if the operations of the businesses of Six Flags and Cedar Fair are integrated successfully, CopperSteel may not realize the full benefits of the Mergers, including the cost savings, workforce efficiencies, scale, or sales and growth opportunities that Six Flags and Cedar Fair expect. In addition, some of the anticipated synergies are not expected to occur for a period of time following the Closing and may involve unanticipated costs and require significant capital expenditures in the near term to be fully realized. Even if CopperSteel is able to integrate the two companies successfully, the anticipated benefits of the Mergers, including the expected synergies, may not be realized fully or at all and may take longer to realize than expected.

If CopperSteel is not able to achieve these objectives and realize the anticipated benefits and synergies expected from the Mergers within the anticipated timeframe or at all, could adversely affect CopperSteel’s results of operation or cash flows, cause dilution to the earnings per share of CopperSteel, decrease or delay any accretive effect of the transactions and negatively impact the price of CopperSteel Common Stock.

The benefits described in this proxy statement/prospectus are also subject to a variety of other factors, many of which are beyond CopperSteel’s ability to control. The impact of these factors, individually and in the aggregate, is difficult to predict, in part because the occurrence of the events or circumstances described in such factors may be interrelated, and the impact to the combined group of the occurrence of any one of these events or circumstances could be compounded or, alternatively, reduced, offset, or more than offset, by the occurrence of one or more of the other events or circumstances described in such factors.

The financial forecasts are based on various assumptions that may not be realized.

The financial estimates set forth in the forecasts included in the section entitled “The Mergers — Certain Unaudited Prospective Financial Information” were based on assumptions of, and information available to, Six Flags management and Cedar Fair management, as applicable, when prepared, and these estimates and assumptions are subject to uncertainties, many of which are beyond Six Flags’ and Cedar Fair’s control and may not be realized. Many factors mentioned in this proxy statement/prospectus, including the risks outlined in this “Risk Factors” section and the events or circumstances described under “Cautionary Statement Regarding Forward-Looking Statements,” will be important in determining CopperSteel’s future results. As a result of these contingencies, actual future results may vary materially from Six Flags’ and Cedar Fair’s estimates. In view of these uncertainties, the inclusion of financial estimates in this proxy statement/prospectus is not and should not be viewed as a representation that the forecasted results will necessarily reflect actual future results.

Six Flags’ and Cedar Fair’s financial estimates were not prepared with a view toward public disclosure, and such financial estimates were not prepared with a view toward compliance with published guidelines of any regulatory or professional body. Further, any forward-looking statement speaks only as of the date on which it is made, and neither Six Flags nor Cedar Fair undertakes any obligation, other than as required by applicable law, to update the financial estimates herein to reflect events or circumstances after the date those financial estimates were prepared or to reflect the occurrence of anticipated or unanticipated events or circumstances.

The financial estimates of Six Flags and Cedar Fair included in this proxy statement/prospectus have been prepared by, and are the responsibility of, Six Flags and Cedar Fair, as applicable. Moreover, neither Six Flags’ nor Cedar Fair’s independent accountants, nor any other independent accountants, have compiled, examined or performed any procedures with respect to Six Flags’ or Cedar Fair’s respective prospective financial information contained herein, nor have they expressed any opinion or any other form of assurance on such information or achievability thereof, and, accordingly, such independent accountants assume no responsibility for, and disclaim any association with, Six Flags’ and Cedar Fair’s prospective financial information. The reports of such independent accountants included or incorporated by reference herein, as applicable, relate exclusively to the historical financial information of the entities named in those reports and do not cover any other information in

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this proxy statement/prospectus and should not be read to do so. See “The Mergers — Certain Unaudited Prospective Financial Information” for more information.

The future results of CopperSteel following the Mergers will suffer if CopperSteel does not effectively manage its operations.

CopperSteel’s future success will depend, in part, upon its ability to manage the combined businesses of Six Flags and Cedar Fair and continue to retain and attract additional guests to its amusement parks, which will pose substantial challenges for management, including challenges related to the management and monitoring of new operations and associated increased costs and complexity. CopperSteel may also face increased scrutiny from governmental authorities as a result of the Mergers. There can be no assurances that CopperSteel will be successful or that it will realize the expected operating efficiencies, cost savings, growth or other benefits currently anticipated from the Mergers.

The Mergers may result in a loss of suppliers, concessionaires, vendors or other third-party business partners and may result in the termination of existing contracts.

Following the Mergers, some of the suppliers, concessionaires, vendors or other third-party business partners of Six Flags and Cedar Fair may terminate or scale back their current or prospective business relationships with CopperSteel. In addition, Six Flags and Cedar Fair have contracts with suppliers, concessionaires, vendors or other third-party business partners that may require Six Flags or Cedar Fair to obtain consents from these other parties in connection with the Mergers, which may not be obtained on favorable terms or at all. If relationships with suppliers, concessionaires, vendors or other third-party business partners are adversely affected by the Mergers, or if CopperSteel, following the Mergers, loses the benefits of the contracts of Six Flags and Cedar Fair, CopperSteel’s business and financial performance could suffer.

Declaration, payment and amounts of dividends, if any, distributed to stockholders of CopperSteel will be uncertain.

Although Six Flags and Cedar Fair have paid cash dividends on Six Flags Common Stock and Cedar Fair Units in the past, the CopperSteel Board may determine not to declare dividends in the future or may reduce the amount of dividends paid in the future. Any payment of future dividends will be at the discretion of the CopperSteel Board and will depend on CopperSteel’s results of operations, financial condition, cash requirements, future prospects and other considerations that the CopperSteel Board deems relevant, including, but not limited to:

CopperSteel Stockholders should be aware that they have no contractual or other legal right to dividends that have not been declared.

The trading price and volume of CopperSteel Common Stock may be volatile following the Mergers.

The trading price and volume of CopperSteel Common Stock may be volatile following completion of the Mergers. The stock markets in general have experienced extreme volatility that has often been unrelated to the

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operating performance of particular companies. These broad market fluctuations may adversely affect the trading price of CopperSteel Common Stock. In addition, there will have been no historical market price of the CopperSteel Common Stock. The market price of the CopperSteel Common Stock could fluctuate significantly for many reasons, including in response to the risks described in this section, elsewhere in this proxy statement/prospectus or the documents incorporated by reference in this proxy statement/prospectus or for reasons unrelated to the operations of CopperSteel, such as reports by industry analysts, investor perceptions or negative announcements by customers, competitors or suppliers of CopperSteel regarding their own performance, as well as industry conditions and general financial, economic and political instability. As a result, you may suffer a loss on your investment. Many factors may impair the market for CopperSteel Common Stock and the ability of investors to sell shares at an attractive price, and could also cause the market price and demand for CopperSteel Common Stock to fluctuate substantially, which may negatively affect the price and liquidity of CopperSteel Common Stock. Many of these factors and conditions are beyond the control of the CopperSteel or CopperSteel Stockholders.

CopperSteel has no operating or financial history and the unaudited pro forma condensed combined financial statements and the unaudited prospective financial and operating information prepared by Six Flags and Cedar Fair included in this proxy statement/prospectus are based on a number of assumptions and are preliminary and unaudited. Therefore, the actual results of operations, cash flows and financial position of CopperSteel after the Mergers may differ materially.

CopperSteel has been recently incorporated in connection with the proposed Mergers and has no operating history or revenues. The unaudited pro forma information and the unaudited prospective financial information in this proxy statement/prospectus is presented for illustrative purposes only, has been prepared based on available information and certain assumptions and estimates that Six Flags and Cedar Fair believe are reasonable and is not necessarily indicative of what CopperSteel’s actual financial position or results of operations would have been had the pro forma events been completed on the dates indicated. The pro forma financial statements do not include, among other things, estimated cost or growth synergies, adjustments related to restructuring or integration activities, future acquisitions or disposals not yet known or probable, including those that may be required by regulatory or governmental authorities in connection with the Mergers, or impacts of merger related change in control provisions that are currently not factually supportable and/or probable of occurring. Further, CopperSteel’s actual results and financial position after the pro forma events occur may differ materially and adversely from the unaudited pro forma information included in this proxy statement/prospectus. The unaudited pro forma condensed combined financial statements have been prepared with Cedar Fair as the accounting acquirer under GAAP and reflect adjustments based on preliminary estimates of the fair value of assets to be acquired and liabilities to be assumed.

CopperSteel’s certificate of incorporation designates the Court of Chancery of the State of Delaware as the sole and exclusive forum for certain types of actions and proceedings that may be initiated by CopperSteel Stockholders, which could limit CopperSteel Stockholders’ ability to obtain a favorable judicial forum for disputes with CopperSteel or its directors, officers or other employees.

CopperSteel’s certificate of incorporation provides that, unless CopperSteel consents in writing to the selection of an alternative forum, the Court of Chancery of the State of Delaware (or, if the Court of Chancery does not have jurisdiction, the federal district court for the District of Delaware) shall, to the fullest extent permitted by law, be the sole and exclusive forum for (i) any derivative action or proceeding brought on behalf of CopperSteel, (ii) any action asserting a claim for a breach of a fiduciary duty owed by any director, officer, employee, or agent of CopperSteel to CopperSteel or CopperSteel Stockholders, (iii) any action asserting a claim arising pursuant to any provision of the DGCL or CopperSteel’s organizational documents, (iv) any action asserting a claim governed by the internal affairs doctrine or (v) any action asserting an “internal corporate claim” as that term is defined in Section 115 of the DGCL.

The CopperSteel certificate of incorporation also provides that, unless CopperSteel consents in writing to the selection of an alternative forum, the federal district courts of the United States will be the sole and exclusive

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forum for any action brought under the Securities Act. Any person or entity purchasing or otherwise acquiring any interest in shares of capital stock of CopperSteel is deemed to have received notice of and consented to the forum selection provisions of CopperSteel’s certificate of incorporation. Such provisions may limit CopperSteel Stockholders’ ability to bring a claim in a judicial forum that they find favorable for disputes with CopperSteel or its directors, officers or other employees, which may discourage such lawsuits. Alternatively, if a court were to find the choice of forum provisions inapplicable to, or unenforceable in respect of, one or more of the specified types of actions or proceedings, CopperSteel may incur additional costs associated with resolving such matters in other jurisdictions, which could adversely affect its business, financial condition, prospects or results of operations.

Other Risk Factors Relating to Six Flags and Cedar Fair

As a result of entering into the Merger Agreement, Six Flags’ and Cedar Fair’s businesses are and will be subject to the risks described above. In addition, Six Flags and Cedar Fair are, and following completion of the Mergers, CopperSteel will be, subject to the risks described in Six Flags’ and Cedar Fair’s most recent Annual Report on Form 10-K, as updated by subsequent Quarterly Reports on Form 10-Q, which are filed with the SEC and incorporated by reference into this proxy statement/prospectus. See “Where You Can Find More Information” for the location of information incorporated by reference into this proxy statement/prospectus.

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SIX FLAGS SPECIAL MEETING

General

This proxy statement/prospectus is being provided to Six Flags Stockholders as part of a solicitation of proxies by the Six Flags Board for use at the Six Flags Special Meeting and at any adjournments or postponements of such special meeting. This proxy statement/prospectus provides Six Flags Stockholders with important information about the Six Flags Special Meeting and should be read carefully in its entirety.

Date, Time and Place of the Six Flags Special Meeting

The Six Flags Special Meeting will be held at 10:00 a.m., Central Time, on March 12, 2024. The Six Flags Special Meeting will be held in person at Six Flags Entertainment Corporation Corporate Headquarters, Choctaw Stadium, 1000 Ballpark Way, Arlington, TX 76011.

Purposes of the Six Flags Special Meeting

The Six Flags Special Meeting is being held to consider and vote on the following proposals:

Recommendation of the Six Flags Board

The Six Flags Board unanimously recommends that Six Flags Stockholders vote:

This proxy statement/prospectus contains important information regarding these proposals and factors that Six Flags Stockholders should consider when deciding how to cast their votes. Six Flags Stockholders are encouraged to read the entire document carefully, including the annexes attached and documents incorporated by reference into this proxy statement/prospectus, for more detailed information regarding the Merger Agreement and the Mergers.

Interests of Certain Six Flags Directors and Executive Officers in the Mergers

In considering the recommendation of the Six Flags Board with respect to the Merger Agreement, Six Flags Stockholders should be aware that, aside from their interests as Six Flags Stockholders, Six Flags’ directors and

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executive officers have interests in the Mergers that may be different from, or in addition to, the interests of Six Flags Stockholders generally, including, but not limited to, the treatment of outstanding Six Flags Equity Awards pursuant to the Merger Agreement, potential severance and other benefits upon a qualifying termination of employment in connection with the Mergers, eligibility, in the case of Mr. Bassoul, for a cash transaction bonus, eligibility for payment of an annual bonus in respect of 2023 and (depending on the timing of Closing) eligibility for payment of a pro-rated annual bonus in respect of 2024, and rights to ongoing indemnification and insurance coverage. These interests are described in more detail in the section entitled “The Mergers — Interests of Certain Six Flags Directors and Executive Officers in the Mergers.” The Six Flags Board was aware of and considered these potential interests, among other matters, in evaluating and negotiating the Merger Agreement and the transactions contemplated therein, in approving the Mergers and in recommending the adoption of the Merger Agreement Proposal. See the section entitled “The Mergers — Background of the Mergers” and “The Mergers — Recommendation of the Six Flags Board and Six Flags’ Reasons for the Mergers.”

Record Date

Only Six Flags Stockholders of record as of the close of business on January 24, 2024, the Record Date, are entitled to notice of, and to vote at, the Six Flags Special Meeting or any postponement or adjournment thereof.

Outstanding Shares as of Record Date and Voting Rights of Six Flags Stockholders

As of the Record Date, Six Flags had outstanding 84,125,461 shares of Six Flags Common Stock, the only class of outstanding securities entitled to vote at the Six Flags Special Meeting. Each stockholder of Six Flags will be entitled to one vote for each share of Six Flags Common Stock registered in its name on the Record Date. Six Flags Stockholders are entitled to vote on each proposal presented. A complete list of registered Six Flags Stockholders entitled to vote at the Six Flags Special Meeting will be available for inspection at Six Flags’ principal executive offices at 1000 Ballpark Way, Suite 400, Arlington, Texas 76011, during ordinary business hours for a period of no less than ten days before the Six Flags Special Meeting. The list of Six Flags Stockholders will also be available to Six Flags Stockholders during the Six Flags Special Meeting.

Quorum; Abstentions and Broker Non-Votes

In order for business to be conducted at the Six Flags Special Meeting, a quorum must be present. The quorum requirement for holding the Six Flags Special Meeting and transacting business is a majority of the outstanding shares of Six Flags Common Stock entitled to vote. The shares may be present in person or represented by proxy at the meeting. Abstention votes are counted as present for the purpose of determining whether a quorum exists for the Six Flags Special Meeting.

An abstention occurs when the beneficial owner of shares, or a bank, broker or other nominee holding shares for a beneficial owner, is present at the Six Flags Special Meeting or by proxy, and entitled to vote at the meeting, but such person refrains from voting as to a particular proposal by expressly marking the “abstain” box on the voting instruction form or ballot.

A broker non-vote occurs when a broker or other nominee does not receive voting instructions from the beneficial owner and does not have the discretion to direct the voting of the shares. A broker is entitled to vote shares held for a beneficial holder on routine matters without instructions from the beneficial holder of those shares. However, a broker is not entitled to vote shares held for a beneficial holder on non-routine items. We do not expect brokers to have discretionary voting authority in connection with the Merger Agreement Proposal, the Compensation Advisory Proposal or the Adjournment Proposal and therefore there will not be any broker non-votes.

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Vote Required for Approval

The votes required for each proposal are as follows:

Stock Ownership and Voting by Six Flags Directors and Executive Officers

On the Record Date, Six Flags directors and executive officers, and their affiliates, as a group, beneficially owned and were entitled to vote 909,279 shares of Six Flags Common Stock, or approximately 1.08% of the outstanding shares of Six Flags Common Stock. Six Flags currently expects that all of its directors and executive officers will vote their shares “FOR” the Merger Agreement Proposal, “FOR” Compensation Advisory Proposal and “FOR” the Adjournment Proposal even though none of its directors and executive officers have entered into any agreement, other than the Voting and Support Agreement, as described below.

Voting and Support Agreement

Concurrently with the execution of the Merger Agreement, on November 2, 2023, Cedar Fair, H Partners, and, solely for purposes of certain sections therein, Six Flags, entered into a Voting and Support Agreement, pursuant to which H Partners, a significant stockholder of Six Flags Common Stock which owned approximately 13.64% of the outstanding Six Flags Common Stock as of the date of the Merger Agreement, agreed to, among other things, and subject to certain exceptions, vote (or cause to be voted), in person or by proxy at the Six Flags Special Meeting, all shares of Six Flags Common Stock beneficially owned by H Partners as of the date of the Voting and Support Agreement (or thereafter acquired):

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H Partners also agreed to appear in person or by proxy at each meeting or otherwise cause all of its shares to be counted as present for purposes of calculating a quorum.

Notwithstanding the foregoing, in the event that there is any amendment to the Merger Agreement which (w) reduces or changes the form of the Six Flags Merger Consideration, (x) increases or changes the form of Cedar Fair Merger Consideration, (y) changes the payment terms of the Six Flags Merger Consideration in any respect adverse to the holders of shares of Six Flags Common Stock, or (z) effects any change that is materially adverse to the holders of shares of Six Flags Common Stock, H Partners will have no obligation to vote any of its shares in accordance with the Voting and Support Agreement in favor of the Mergers or with respect to the Merger Agreement as so amended or take any other action under the Merger Agreement; and provided, further, that H Partners will retain at all times the right to vote its shares in H Partners’ sole discretion, and without any other limitation, on any matters other than those set forth above and in the Cooperation Agreement that are at any time or from time to time presented for consideration to Six Flags’ Stockholders generally.

Six Flags consented to H Partners’ entrance into the Voting and Support Agreement and waived its rights with respect to certain sections of the Cooperation Agreement. The Voting and Support Agreement provides that Six Flags and H Partners will enter into an amendment to the Cooperation Agreement to have the Cooperation Agreement terminate at the Closing Effective Time.

The Voting and Support Agreement will terminate automatically upon the earliest to occur of (a) the date on which the Mergers become effective, (b) the date on which the Merger Agreement is validly terminated, (c) the Outside Date, and (d) the date on which the parties agree in writing to terminate the Voting and Support Agreement.

Attendance at the Six Flags Special Meeting

Only Six Flags Stockholders of record on the Record Date, beneficial owners of Six Flags Common Stock on the Record Date, holders of valid proxies for the Six Flags Special Meeting and invited guests of Six Flags may attend the Six Flags Special Meeting, which will be conducted in person.

At the Six Flags Special Meeting, Rules of Conduct will be provided to attendees. No recording is allowed at the Six Flags Special Meeting. This includes photography, audio recording and video recording of any kind.

Six Flags will hold a question and answer session immediately following the conclusion of the business to be conducted at the Six Flags Special Meeting.

Parking will be available in Lot K of Choctaw Stadium, located at the northeast corner of Ballpark Way and E. Randol Mill Road. Enter Lot K from westbound E. Randol Mill Road. Parking is complimentary for any stockholder who attends the Six Flags Special Meeting. When you enter the parking lot, take a ticket from the parking lot kiosk. In order to receive complimentary parking, please present your parking ticket at the registration desk for the Six Flags Special Meeting, and you will receive a validation pass for use when exiting the parking lot.

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Voting of Shares

Six Flags Stockholders of record on the Record Date may have their shares of Six Flags Common Stock voted by submitting a proxy or may vote at the Six Flags Special Meeting by following the instructions provided on the enclosed proxy card. Six Flags recommends that Six Flags Stockholders entitled to vote submit a proxy prior to the Six Flags Special Meeting even if they plan to attend the Six Flags Special Meeting.

Six Flags Stockholders of record may vote in one of the following ways:

Six Flags Stockholders are encouraged to submit a proxy promptly. Each valid proxy received in time will be voted at the Six Flags Special Meeting according to the choice specified, if any. Executed but uninstructed proxies (i.e., proxies that are properly signed, dated and returned but are not marked to tell the proxies how to vote) will be voted in accordance with the recommendations of the Six Flags Board.

Six Flags Stockholders who hold their shares of Six Flags Common Stock beneficially in “street name” and wish to submit a proxy must provide instructions to the bank, broker or other nominee that holds their shares of record as to how to vote their shares with respect to Proposals 1, 2, and 3. Six Flags Stockholders who hold their shares of Six Flags Common Stock beneficially and wish to vote at the Six Flags Special Meeting must obtain proxies issued in their own names (known as a “legal proxy”).

Revocation of Proxies

Your proxy may be revoked at any time prior to the Six Flags Special Meeting. If you provide more than one proxy, the proxy having the latest date will revoke any earlier proxy. If you attend the Six Flags Special

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Meeting in person, you will be given the opportunity to revoke your proxy and vote in person. If you are a stockholder of record or hold shares through a broker or bank and are voting by internet or telephone, your vote must be received  by 11:59 p.m., Eastern Time (10:59 p.m., Central Time), on March 11, 2024, to be counted.

Solicitation of Proxies; Expenses of Solicitation

Six Flags and Cedar Fair will pay for the proxy solicitation costs related to the Six Flags Special Meeting. Proxies may be solicited by directors, officers, and employees of Six Flags in person, or by mail, telephone, e-mail, or other electronic means. Six Flags will not specially compensate those persons for their solicitation activities. Six Flags has also made arrangements with Innisfree M&A Incorporated to assist it in soliciting proxies and have agreed to pay it an estimated fee of approximately $100,000 plus expenses for these services. Six Flags may also ask banks, brokers, trusts and other nominees to forward proxy solicitation materials to the Six Flags Stockholders held of record by such banks, brokers, trusts or other nominees. Six Flags and Cedar Fair will reimburse banks, brokers and other nominees for their expenses in sending proxy solicitation materials to the beneficial owners of Six Flags Common Stock and obtaining their proxies.

Appraisal Rights and Dissenters’ Rights

Six Flags Stockholders are entitled to appraisal rights under Section 262 of the DGCL with respect to the Merger Agreement Proposal, provided they satisfy the special criteria and conditions set forth in Section 262 of the DGCL. Six Flags Stockholders have no appraisal rights with respect to the Compensation Advisory Proposal.

For more information regarding Six Flags Stockholders’ dissenters’ or appraisal rights, please see the section entitled “The Mergers — Appraisal Rights and Dissenters’ Rights.”

Householding of Proxy Materials

The SEC rules permit companies and intermediaries (such as banks and brokers) to satisfy the delivery requirements for proxy statements and related materials for two or more stockholders sharing the same address by delivering a single proxy statement to that address unless contrary instructions have been received from one of the affected stockholders. This process, which is commonly referred to as “householding”, provides convenience for stockholders and cost savings for Six Flags.

If, at any time, a stockholder no longer wishes to participate in householding and would prefer to receive a separate proxy statement and related materials, or if a stockholder’s household is receiving multiple copies of these documents and the stockholder desires that future deliveries be limited to a single copy, such stockholder should please notify his or her broker.

Adjournments and Postponements

If a quorum is not present or represented, the Six Flags Stockholders entitled to vote thereat, present in person or represented by proxy, may, by a majority in voting power thereof, adjourn the Six Flags Special Meeting from time to time. The meeting may also be adjourned for any or no reason by the person presiding over the meeting of Six Flags Stockholders. When a meeting is adjourned to another place, date or time, notice need not be given if the place, if any, date and time thereof, and the means of remote communications, if any, by which Six Flags Stockholders and proxy holders may be deemed to be present in person and vote at such adjourned meeting, are announced at the meeting at which the adjournment is taken. However, if the adjournment is for more than 30 calendar days, a new notice shall be provided to each Six Flags Stockholder of record. At such adjourned meeting at which a quorum shall be present or represented, any business may be transacted which might have been transacted at the Six Flags Special Meeting as originally notified.

Although it is not currently expected, the Six Flags Special Meeting may be adjourned or postponed one or more times to a later day or time if necessary or appropriate, including to solicit additional proxies in favor of the

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Merger Agreement Proposal or to ensure that any supplement or amendment to this proxy statement/prospectus is timely provided to Six Flags Stockholders. Your shares of Six Flags Common Stock will be voted on any Adjournment Proposal in accordance with the instructions indicated in your proxy.

Even if a quorum is not present at the Six Flags Special Meeting, the Six Flags Special Meeting may be adjourned to another place, date or time by the affirmative vote of shares of Six Flags Common Stock representing a majority of the shares of Six Flags Common Stock present virtually or represented by proxy at the Six Flags Special Meeting entitled to vote on such matter. The adjourned meeting may take place without further notice other than by an announcement made at the Six Flags Special Meeting unless the adjournment is for more than 30 days thereafter or, if, after the adjournment, a new Record Date is fixed for the adjourned meeting, in which case a notice of the adjourned meeting will be given to each stockholder of record entitled to vote at the Six Flags Special Meeting. Pursuant to the Six Flags Bylaws, the Chairman of the Six Flags Board or such other officer of Six Flags designated by the Six Flags Board, may adjourn the Six Flags Special Meeting, for any or no reason, to any other time and to any other place at which a meeting of stockholders may be held under the Six Flags Bylaws.

Questions and Additional Information

Six Flags Stockholders may contact Six Flags’ Corporate Secretary or Six Flags’ proxy solicitors with any questions about the proposals or how to vote or to request additional copies of any materials at:

Investor Relations

Six Flags Entertainment Corporation.

1000 Ballpark Way, Suite 400

Arlington, Texas 76011

(972) 595-5000

Innisfree M&A Incorporated

501 Madison Avenue, 20^th Floor

New York, New York 10022

Banks and Brokerage Firms, Please Call: (212) 750-5833

Stockholders and All Others Call Toll Free: (877) 750-0854

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PROPOSAL 1 — MERGER AGREEMENT PROPOSAL

Overview

This proxy statement/prospectus is being furnished to Six Flags Stockholders as part of the solicitation of proxies by the Six Flags Board for use at the Six Flags Special Meeting to consider and vote upon a proposal to adopt the Merger Agreement, which is attached as Annex A to this proxy statement/prospectus, and approve the transactions contemplated thereby, including the Six Flags Merger.

The Six Flags Board, after due and careful discussion and consideration, unanimously (i) determined that the Merger Agreement and the Six Flags Merger were advisable, and in the best interests of, Six Flags and the Six Flags Stockholders, (ii) approved (A) the form, terms and conditions of the Merger Agreement, (B) the execution, delivery and performance by Six Flags thereof and (C) subject to the adoption of the Merger Agreement at the Six Flags Special Meeting, the consummation of the transactions contemplated by the Merger Agreement, including the Six Flags Merger and the declaration of the Special Dividend, (iii) resolved to recommend that the Six Flags Stockholders adopt the Merger Agreement on the terms and subject to the conditions set forth in the Merger Agreement and (iv) directed that the adoption of the Merger Agreement be submitted to the Six Flags Stockholders at the Six Flags Special Meeting.

Vote Required for Approval

Approval of the Merger Agreement Proposal requires the affirmative vote of the holders of a majority of the outstanding shares of Six Flags Common Stock entitled to vote in person or by proxy thereon. Accordingly, a Six Flags Stockholder’s abstention from voting at the Six Flags Special Meeting will have the same effect as a vote “AGAINST” the Merger Agreement Proposal. We do not expect brokers to have discretionary voting authority in connection with the Merger Agreement Proposal and therefore there will not be any broker non-votes. The Mergers cannot be completed without the approval of the Merger Agreement Proposal.

Recommendation of the Six Flags Board

The Six Flags Board, after due and careful discussion and consideration, unanimously approved and recommended the adoption of the Merger Agreement and the transactions contemplated therein, including the Mergers.

The Six Flags Board unanimously recommends that Six Flags Stockholders vote “FOR” the Merger Agreement Proposal.

IF YOU ARE A SIX FLAGS STOCKHOLDER,

THE SIX FLAGS BOARD UNANIMOUSLY RECOMMENDS

THAT YOU VOTE “FOR” THE ADOPTION OF THE MERGER AGREEMENT PROPOSAL

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PROPOSAL 2 — COMPENSATION ADVISORY PROPOSAL

Overview

Pursuant to Section 14A of the Exchange Act and Rule 14a-21(c) thereunder, Six Flags is seeking a non-binding advisory stockholder approval of the compensation of Six Flags’ named executive officers that is based on or otherwise relates to the Mergers as disclosed in “The Mergers — Quantification of Potential Payments and Benefits to Six Flags’ Named Executive Officers in Connection with the Mergers.” The proposal gives Six Flags Stockholders the opportunity to express their views on the compensation of Six Flags’ named executive officers.

Six Flags Stockholders should note that the Compensation Advisory Proposal is merely an advisory vote that will not be binding on Six Flags, CopperSteel or their respective boards of directors. Further, the underlying plans and arrangements are contractual in nature and not, by their terms, subject to stockholder approval.

Vote Required for Approval

The vote on the Compensation Advisory Proposal is a vote separate and apart from the vote on the Merger Agreement Proposal. Accordingly, Six Flags Stockholders may vote to approve the Merger Agreement Proposal and vote not to approve the Compensation Advisory Proposal, and vice versa. The approval of the Compensation Advisory Proposal is not a condition to the Closing or otherwise required to effectuate the Mergers. If the Mergers are completed, the compensation may be paid to Six Flags’ named executive officers to the extent payable in accordance with the terms of the compensation agreements and arrangements even if the Six Flags Stockholders fail to approve the Compensation Advisory Proposal.

As an advisory vote, this Compensation Advisory Proposal is not binding on Six Flags. However, Six Flags values the opinions expressed by its stockholders, and the Six Flags Board will carefully review and take into account the results of the vote when designing and considering the compensation agreements and arrangements with Six Flags’ named executive officers if the Mergers are completed.

Approval of the Compensation Advisory Proposal, on a non-binding advisory basis, requires the affirmative vote of holders of a majority of the shares of Six Flags Common Stock present in person or represented by proxy at the Six Flags Special Meeting and entitled to vote thereon. Accordingly, a Six Flags Stockholder’s abstention from voting at the Six Flags Special Meeting will have the same effect as a vote “AGAINST” the Compensation Advisory Proposal. We do not expect brokers to have discretionary voting authority in connection with the Compensation Advisory Proposal and therefore there will not be any broker non-votes.

Recommendation of the Six Flags Board

The Six Flags Board unanimously recommends that Six Flags Stockholders vote “FOR” the adoption of the following resolution, on a non-binding advisory basis:

“RESOLVED, that Six Flags Stockholders approve, on a non-binding advisory basis, the compensation that may be paid or become payable to Six Flags’ named executive officers that is based on or otherwise relates to the Mergers, as disclosed pursuant to Item 402(t) of Regulation S-K under the heading “The Mergers — Quantification of Potential Payments and Benefits to Six Flags’ Named Executive Officers in Connection with the Mergers” (which disclosure includes the compensation table and related narrative named executive officer compensation disclosures required pursuant to Item 402(t) of Regulation S-K).”

IF YOU ARE A SIX FLAGS STOCKHOLDER,

THE SIX FLAGS BOARD UNANIMOUSLY RECOMMENDS

THAT YOU VOTE “FOR” THE COMPENSATION ADVISORY

PROPOSAL ON A NON-BINDING ADVISORY BASIS

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PROPOSAL 3 — ADJOURNMENT PROPOSAL

Overview

The Adjournment Proposal, if adopted, will allow the Six Flags Board to adjourn the Six Flags Special Meeting, if necessary, to a later date or dates at the determination of the Six Flags Board, including to solicit additional proxies in favor of the Merger Agreement Proposal if there are insufficient votes at the time of the Six Flags Special Meeting to approve the Merger Agreement Proposal or to ensure that any supplement or amendment to this proxy statement/prospectus is timely provided to Six Flags Stockholders.

Six Flags is asking its stockholders to authorize the holder of any proxy solicited by the Six Flags Board to vote in favor of any adjournment to the Six Flags Special Meeting to solicit additional proxies if there are not sufficient votes to approve the Merger Agreement Proposal or to ensure that any supplement to this proxy statement/prospectus is timely provided to Six Flags Stockholders.

Vote Required for Approval

Approval of the Adjournment Proposal requires the affirmative vote of holders of a majority of the shares of Six Flags Common Stock present in person or represented by proxy at the Six Flags Special Meeting and entitled to vote thereon, even if a quorum is not present at the Six Flags Special Meeting. Accordingly, a Six Flags Stockholder’s abstention from voting at the Six Flags Special Meeting will have the same effect as a vote “AGAINST” the Adjournment Proposal. We do not expect brokers to have discretionary voting authority in connection with the Adjournment Proposal and therefore there will not be any broker non-votes.

Recommendation of the Six Flags Board

The Six Flags Board unanimously recommends that Six Flags Stockholders vote “FOR” the Adjournment Proposal.

IF YOU ARE A SIX FLAGS STOCKHOLDER,

THE SIX FLAGS BOARD UNANIMOUSLY RECOMMENDS

THAT YOU VOTE “FOR” THE ADJOURNMENT PROPOSAL

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THE MERGERS

This section of the proxy statement/prospectus describes the material aspects of the Mergers. This section may not contain all of the information that is important to you. You should carefully read this entire proxy statement/prospectus and the documents attached hereto and incorporated by reference into this proxy statement/prospectus, including the full text of the Merger Agreement, a copy of which is attached to this proxy statement/prospectus as Annex A, for a more complete understanding of the Mergers and the transactions related thereto. In addition, important business and financial information about each of Six Flags and Cedar Fair is included in or incorporated by reference into this proxy statement/prospectus and is included in the annexes hereto. Please see the section entitled “Where You Can Find More Information.”

General

Six Flags is seeking the adoption by Six Flags Stockholders of the Merger Agreement that Six Flags entered into on November 2, 2023 with Cedar Fair, CopperSteel and Copper Merger Sub. Under the terms of the Merger Agreement, (i) Copper Merger Sub will merge with and into Cedar Fair with Cedar Fair continuing as the surviving corporation and a direct subsidiary of CopperSteel, (ii) the Cedar Fair Surviving Entity will merge with and into CopperSteel, with CopperSteel continuing as the surviving corporation, and (iii) Six Flags will merge with and into CopperSteel with CopperSteel continuing as the surviving corporation.

Following the completion of the Mergers, at the Closing Effective Time, Six Flags and Cedar Fair will cease to be separate publicly traded companies, as Six Flags and Cedar Fair will each have been merged with and into CopperSteel, with CopperSteel as the parent entity and successor corporation to Six Flags and Cedar Fair. Upon Closing, CopperSteel will be headquartered in Charlotte, North Carolina, and is expected to change its name to “Six Flags Entertainment Corporation” and be listed on NYSE under the ticker symbol “FUN.”

Background of the Mergers

As part of the ongoing review of their respective companies’ businesses, each of the Six Flags Board and the Cedar Fair Board and each of Six Flags and Cedar Fair management, with the assistance of their respective outside advisors, regularly evaluate their respective companies’ historical performance, future growth prospects, competitive performance and overall strategic objectives and consider potential opportunities available to each company. In addition, as part of each company’s ongoing efforts to strengthen its overall business and enhance value for each company’s respective equityholders, each of the Six Flags Board and Cedar Fair Board and each of Six Flags and Cedar Fair management regularly review and evaluate various potential strategic alternatives, partnerships, investments and other strategic transactions and opportunities (including the continuation of each company as a standalone company), and the potential benefits and risks of such transactions in light of economic, regulatory, competitive and other conditions, including the state of the out-of-home entertainment industry, an evolving customer and vendor landscape, financing costs and climate change.

As active participants in the out-of-home entertainment industry, where the parties compete with amusement parks, aquariums, competitive social games, family entertainment centers, museums, water parks, zoos, and numerous other out-of-home entertainment options, Six Flags’ management team was generally familiar with Cedar Fair, its management team and its business. In addition, Selim Bassoul, Chief Executive Officer of Six Flags, and Richard Zimmerman, Chief Executive Officer of Cedar Fair, met on occasion to discuss, among other things, trends in the out-of-home entertainment industry and their respective businesses.

On July 21, 2023, Mr. Zimmerman contacted Mr. Bassoul and requested a meeting to discuss a potential transaction between the two companies.

On August 1, 2023, Mr. Bassoul, Gary Mick, Chief Financial Officer of Six Flags, Mr. Zimmerman and Brian Witherow, Chief Financial Officer of Cedar Fair, met in-person in Dallas, Texas. During the course of this

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discussion, Mr. Zimmerman stated that the Cedar Fair Board had authorized him to approach Mr. Bassoul to explore a potential combination of Six Flags and Cedar Fair through a stock-for-stock merger of equals, which Cedar Fair believed could result in significant strategic benefits including increased park offerings and investment opportunities, a stronger balance sheet and potential synergies. Mr. Zimmerman also indicated that Cedar Fair was contemplating an “at market” transaction leading to an approximate 50/50 pro forma ownership split between each company’s equityholders, that Mr. Zimmerman would serve as Chief Executive Officer of the combined company and Mr. Bassoul would serve as Non-Executive Chairman of the board of the combined company, and that the board of the combined company would consist of an equal number of designees from both Six Flags and Cedar Fair. Later on August 1, 2023, Mr. Witherow sent Mr. Mick a draft non-disclosure agreement.

Following the meeting, Mr. Bassoul contacted Goldman Sachs and Kirkland & Ellis LLP, which we refer to as “Kirkland,” legal counsel to Six Flags, to assist Six Flags in evaluating the potential transaction outlined by Cedar Fair. Each of Goldman Sachs and Kirkland had previously provided advisory services to Six Flags.

Thereafter on August 1, 2023, Mr. Bassoul called Ben Baldanza, the Non-Executive Chairman of the Six Flags Board, and notified Mr. Baldanza of the meeting between Messrs. Bassoul, Mick, Zimmerman and Witherow.

On August 2, 2023, Messrs. Bassoul, Mick, Baldanza, representatives of Kirkland and representatives of Goldman Sachs discussed the meeting with Cedar Fair. During the discussion, it was determined that a special board meeting should be called to update the Six Flags Board on the meeting and the potential transaction outlined by Cedar Fair and to obtain the Six Flags Board’s feedback with respect to next steps, if any.

On August 8, 2023, the Six Flags Board held a special meeting by video conference, with members of Six Flags senior management and representatives of Kirkland and Goldman Sachs in attendance. During the meeting, members of Six Flags senior management informed the Six Flags Board of the meeting with Cedar Fair held on August 1, 2023 and of Cedar Fair’s interest in a potential stock-for-stock merger of equals between the two companies. Representatives of Goldman Sachs provided an overview of the financial profiles of Six Flags and Cedar Fair, highlighting the need to understand the potential strategic benefits of the potential transaction, including expanded park offerings, increased investment opportunities and potential synergies, and the financial profile of the combined company in order to determine whether a potential transaction could improve guest experience and create more value for Six Flags Stockholders than Six Flags remaining a standalone company. Representatives of Goldman Sachs also noted certain topics that would need to be evaluated if the Six Flags Board decided to explore the potential transaction, including preferred structure of the potential transaction in light of debt and tax considerations and the ability of Six Flags and Cedar Fair to effectively achieve any potential synergies. Members of the Six Flags Board and representatives of Goldman Sachs and Kirkland discussed various aspects of the potential transaction, including potential relative ownership levels, time required to conduct fulsome due diligence, synergy analysis and execution and integration considerations. During this discussion, Messrs. Bassoul and Mick indicated their willingness to consider stepping down from their current roles, but continuing with the combined company in positions the Six Flags Board deemed appropriate, if the Six Flags Board determined the potential transaction would provide strategic benefits and maximize value for Six Flags Stockholders. Representatives of Kirkland also discussed with the Six Flags Board certain legal matters, including the importance of confidentiality and certain aspects of public company strategic transactions. Following discussion, the Six Flags Board approved the engagement of Kirkland and Goldman Sachs in connection with the potential transaction and authorized members of Six Flags senior management to move forward in evaluating a potential transaction with Cedar Fair, including by executing a mutual non-disclosure agreement with Cedar Fair to facilitate exchanging information and initiating conversations with Cedar Fair and its advisors regarding the combined company’s financial profile, development of transaction structure alternatives and potential synergies.

On August 11, 2023, following discussion and exchange of drafts, Six Flags and Cedar Fair executed a mutual non-disclosure agreement in regard to the potential transaction, which included a mutual standstill

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provision covering an 18-month period that permitted either party to make confidential proposals to the other party’s board of directors, with a customary “fall away” provision providing that the standstill obligations would terminate following, among other things, the other party entering into a definitive agreement providing for a change of control and a “don’t ask, don’t waive” provision, which bars the parties from publicly requesting an amendment or waiver of the standstill during the standstill period. In addition, on August 14, 2023, representatives of Weil, Gotshal & Manges LLP, legal counsel to Cedar Fair, which we refer to as “Weil,” sent an initial draft mutual clean team agreement to representatives of Kirkland to facilitate the sharing of certain non-public, competitively sensitive information. Following negotiations and the exchange of revised drafts of the clean team agreement, Six Flags and Cedar Fair executed the clean team agreement on August 30, 2023.

Between August 14, 2023, and September 5, 2023, representatives of Goldman Sachs, Perella Weinberg Partners L.P., financial advisor to Cedar Fair, which we refer to as “Perella Weinberg,” Kirkland and Weil, and members of senior management of Six Flags and Cedar Fair, held a number of meetings to begin to discuss potential synergies and structuring options for the potential transaction.

On August 23, 2023, the Six Flags Board held a regularly-scheduled board meeting in person and by video conference, with members of Six Flags senior management and representatives of Kirkland and Goldman Sachs in attendance. At the meeting, representatives of Goldman Sachs provided an update to the Six Flags Board on preliminary discussions with Cedar Fair, noting that Six Flags and Cedar Fair had entered into a mutual non-disclosure agreement and the parties and their respective advisors were engaging in discussions regarding structuring considerations and potential strategic benefits in connection with the potential transaction. Representatives from Kirkland reviewed with the Six Flags directors the fiduciary duties of the Six Flags Board in connection with the potential transaction with Cedar Fair. Members of Six Flags senior management then reviewed with the Six Flags Board certain preliminary prospective financial information for Six Flags, including underlying assumptions and variables. Following discussion, the Six Flags Board determined such preliminary financial information was an appropriate reference point for commencing due diligence and discussions with Cedar Fair and directed members of Six Flags senior management to continue to refine the preliminary financial information. Members of Six Flags senior management then reviewed with the Six Flags Board an initial assessment of potential synergies that could result from the potential transaction, which remained subject to continued review and due diligence. Following discussion, the Six Flags Board expressed its support for continued discussions and information sharing between Six Flags and Cedar Fair.

On August 31, 2023, Mr. Zimmerman called Mr. Bassoul to confirm that representatives of Goldman Sachs, Perella Weinberg, Kirkland and Weil were working together to prepare a confidential virtual data room. During the call, Mr. Zimmerman suggested that the companies’ respective management teams meet on September 21, 2023 to discuss initial findings.

On September 10, 2023, Six Flags and Cedar Fair made available to the other (and its respective advisors) certain due diligence information in confidential virtual data rooms, including the Six Flags preliminary prospective financial information and certain unaudited prospective financial information with respect to Cedar Fair on a standalone basis for the fiscal years 2023 through 2028 prepared by Cedar Fair management (the “Cedar Fair Standalone Projections”).

During the period from September 10, 2023, when the virtual data rooms were opened, through November 2, 2023, the date of the execution of the Merger Agreement, representatives and advisors of Six Flags and Cedar Fair engaged in a mutual business and legal due diligence review, which included a number of discussions between representatives and advisors of each party.

On September 19, 2023, Six Flags and Goldman Sachs entered into an engagement letter formally retaining Goldman Sachs as Six Flags’ financial advisor in connection with the potential transaction with Cedar Fair. Six Flags engaged Goldman Sachs as its financial advisor based on Goldman Sachs’ qualifications, experience and familiarity with Six Flags, its industry and merger of equals transactions. Prior to the engagement of Goldman

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Sachs, Goldman Sachs delivered on August 31, 2023 a customary relationship disclosure letter to Six Flags, which did not present any material conflict that would impact the ability of Goldman Sachs to act as a financial advisor to the Six Flags Board.

Between September 21, 2023 and September 23, 2023, members of Six Flags senior management, representatives of Goldman Sachs, members of Cedar Fair senior management and representatives of Perella Weinberg met in-person at Kirkland’s office in Dallas, Texas to discuss the preliminary financial information exchanged between the parties, potential synergies from the potential transaction and the legal structure of the potential transaction, and to begin developing a combined company model. Representatives from Kirkland and Weil also attended the meeting telephonically to discuss the legal structure of the potential transaction.

Between September 23, 2023 and October 10, 2023, members of Six Flags senior management, representatives of Goldman Sachs, members of Cedar Fair senior management and representatives of Perella Weinberg held a number of meetings to continue to analyze and discuss potential synergies and to develop a combined company model.

On September 26, 2023, the Six Flags Board held a special board meeting by video conference, with Six Flags senior management and representatives of Kirkland and Goldman Sachs in attendance. Members of Six Flags senior management provided an update to the Six Flags Board on the potential transaction with Cedar Fair, including status of the review, and assessment of the achievability, of potential synergies in connection with the potential transaction. Representatives of Kirkland provided an overview of the proposed structure of the potential transaction, noting that a transaction structure that included Cedar Fair Unitholders owning more than 51% of the combined company would minimize debt breakage costs, was intended to generally allow Six Flags Stockholders and certain Cedar Fair Unitholders to receive merger consideration without recognizing gain or loss for U.S. federal income tax purposes and, though it would require a vote of the Six Flags Stockholders, would not require a vote of the Cedar Fair Unitholders. The Six Flags Board discussed the structuring considerations, and representatives of Goldman Sachs noted that, in light of the contemplated 50/50 “at the market” transaction, a pre-Closing dividend could potentially be used to provide Six Flags Stockholders with additional consideration value. The Six Flags Board then discussed the strategic rationale for the potential transaction, including expanded park offerings and investment opportunities, a stronger balance sheet and potential synergies, and other considerations relating to the potential transaction, including the importance of Messrs. Bassoul and Mick remaining at the combined company to drive achievement of such potential synergies. The Six Flags Board also discussed certain risks in connection with the potential transaction. Following discussion, the Six Flags Board expressed its support for Six Flags management and advisors to continue to evaluate the potential transaction.

On September 27, 2023, Mr. Bassoul called Mr. Zimmerman to provide an update on the special meeting held by the Six Flags Board the previous day. Mr. Bassoul informed Mr. Zimmerman that the Six Flags Board authorized him to continue discussions with Cedar Fair regarding the potential transaction and that Six Flags’ advisors would expedite the preparation of the virtual data room.

On October 4, 2023, representatives of Weil sent an initial draft of the merger agreement to representatives of Kirkland. The initial draft proposed, among other things, that (i) Cedar Fair Unitholders would hold at least 51.1% of the combined company, (ii) Mr. Zimmerman would serve as the Chief Executive Officer of the combined company, Mr. Bassoul would serve as the Non-Executive Chairman of the board of the combined company and other officer positions would be mutually agreed by the parties, (iii) the board of the combined company would consist of twelve directors with six designees from each of Six Flags and Cedar Fair, and (iv) Six Flags would be required to pay a termination fee equal to 4% of the implied equity value of Six Flags if the merger agreement was terminated under certain circumstances. The draft merger agreement also included reciprocal non-solicitation and change of recommendation provisions, and a so-called “force the vote” provision requiring Six Flags to hold a stockholder meeting to vote on the potential transaction even if the Six Flags Board changed its recommendation in respect of the transaction following execution of a definitive agreement. From this time until the merger agreement was executed on November 2, 2023, representatives of Kirkland and

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representatives of Weil exchanged several drafts of the merger agreement and negotiated the terms of the merger agreement, including with respect to governance arrangements, management of the combined company, restrictions on the parties’ ability to solicit or engage with third party bidders, restrictions on the parties’ respective businesses between signing and Closing, the termination fee amount and the circumstances in which the termination fee would be payable by Six Flags.

On October 6, 2023, the Six Flags Board held a special board meeting by video conference, with members of Six Flags senior management and representatives of Kirkland and Goldman Sachs in attendance. Members of Six Flags senior management presented to the Six Flags Board a summary of preliminary financial projections with respect to Six Flags on a standalone basis for the fiscal years 2023 through 2028 (the “Six Flags Standalone Projections”). The Six Flags Board approved the Six Flags Standalone Projections and directed that the Six Flags Standalone Projections be provided to Cedar Fair for combined company modeling and to Goldman Sachs for use in its valuation analysis. Members of Six Flags senior management and representatives of Goldman Sachs then provided an update on discussions with Cedar Fair, noting that management teams from both companies continued to make progress on developing the combined company plan, identifying and validating potential synergies and conducting due diligence review. Members of Six Flags senior management and representatives of Goldman Sachs then discussed with the Six Flags Board the strategic rationale for, and potential risks of, the potential transaction with Cedar Fair. Among other benefits, members of the Six Flags Board noted that the potential transaction would increase geographical diversity for the combined company, thereby minimizing exposure to regional weather trends, enable cost reductions and create a company with a stronger balance sheet. Members of Six Flags senior management and the Six Flags Board further discussed potential cost and revenue uplift of the potential transaction and the likelihood and timeline for achievement of such synergies. Representatives of Kirkland provided an overview to the Six Flags Board of the preliminary issues raised by the draft of the merger agreement received from representatives of Weil on October 4, 2023. Representatives of Goldman Sachs reviewed and discussed with the Six Flags Board various third parties that participate in the out-of-home entertainment industry and their respective potential levels of interest in and ability to pursue an alternative transaction with Six Flags or Cedar Fair.

On October 13, 2023, Messrs. Zimmerman, Bassoul, Baldanza and Daniel Hanrahan, Chairman of the Cedar Fair Board, met to discuss achievability of potential synergies in connection with the potential transaction and the potential roles that Messrs. Bassoul, Zimmerman and Mick would have in integration planning and execution.

Also on October 13, 2023, the Six Flags Board held a special board meeting via video conference, with members of Six Flags senior management and representatives of Kirkland and Goldman Sachs in attendance. The Six Flags Board discussed with representatives of Kirkland the key terms of the draft merger agreement received from Weil on October 4, 2023, including the form of consideration, closing conditions, social and governance terms, including management of the combined company and the proposal that the board of the combined company would consist of six designees from each of Six Flags and Cedar Fair, deal protection provisions and treatment of equity awards. Representatives of Kirkland explained that the draft merger agreement contemplated that Cedar Fair Unitholders would hold over 51% of the combined company because such ownership structure had a number of favorable benefits for the potential transaction, including avoiding significant debt breakage costs in connection with the potential transaction, generally allowing Six Flags Stockholders and certain Cedar Fair Unitholders to receive merger consideration without recognizing gain or loss for U.S. federal income tax purposes, and discussed with the Six Flags Board the inclusion in the merger agreement of a pre-Closing special dividend to Six Flags Stockholders in order to effectively equalize the consideration value to 50% for each company’s equityholders. Additionally, the proposed ownership structure would not require a vote of Cedar Fair Unitholders. Members of the Six Flags Board discussed the terms of the draft merger agreement, including Cedar Fair’s proposal that Mr. Bassoul serve as Non-Executive Chairman of the board of the combined company and Mr. Zimmerman serve as Chief Executive Officer of the combined company. Members of the Six Flags Board expressed their view that it would be important for Mr. Bassoul and Mr. Mick to have key roles at the combined company in order to help drive integration efforts, culture alignment and synergy achievement, and therefore that Mr. Bassoul should be the Executive Chairman, rather than the Non-Executive Chairman, of the combined

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company, and Mr. Mick should be Chief Integration Officer of the combined company. During this discussion, both Messrs. Bassoul and Mick reiterated their willingness to consider stepping down from their current roles but continuing with the combined company in positions the Six Flags Board deemed appropriate if the Six Flags Board determined to proceed with the potential transaction. Members of the Six Flags Board also discussed the composition of the committees of the board of combined company. Representatives of Goldman Sachs then provided an update on other aspects of the transaction, including the due diligence process and synergies analysis, and provided an overview of refinancing considerations in connection with the potential transaction. Following discussion, the Six Flags Board expressed its support for Six Flags management and advisors to continue to evaluate the potential transaction.

On October 15, 2023, representatives of Kirkland sent representatives of Weil a revised draft of the merger agreement. The revised draft accepted that Cedar Fair Unitholders would hold at least 51.1% of the combined company but proposed that the Six Flags Board would declare a special cash dividend prior to the closing of the potential transaction, payable to Six Flags Stockholders following the closing of the potential transaction. The revised draft also proposed, among other things, that (i) Mr. Bassoul would be the Executive Chairman of the board of the combined company, (ii) Mr. Witherow would be the Chief Financial Officer of the combined company, (iii) Mr. Mick would be the Chief Integration Officer of the combined company, committees of the board of the combined company would consist of an equal number of Six Flags and Cedar Fair designees, and that the chair of the audit committee of the combined company would be designated by Cedar Fair, while the chair of the nominating and governance and compensation committees of the combined company would be designated by Six Flags, (iv) the termination fee payable in certain circumstances by Six Flags would equal 3% of the implied equity value of Six Flags, (v) Cedar Fair would be prohibited from soliciting or entertaining competing proposals, without exception for potential superior proposals, and (vi) the Cedar Fair Board would not be able to change its recommendation in favor of the transaction, given there would be no vote of the Cedar Fair Unitholders.

On October 17, 2023, representatives of Weil sent an initial draft of the voting and support agreement with H Partners, to representatives of Kirkland. Between October 18, 2023 and November 1, 2023, Sullivan and Cromwell LLP, which we refer to as “S&C”, counsel to H Partners, Six Flags’ largest stockholder, Kirkland and Weil exchanged drafts of the voting and support agreement, which was finalized on November 1, 2023 and executed on November 2, 2023.

On October 19, 2023, representatives of Weil sent representatives of Kirkland a revised draft of the merger agreement, which proposed, among other things, that Mr. Bassoul would be the Non-Executive Chairman of the board of the combined company, Mr. Mick would serve in an to-be-determined integration role at the combined company, the termination fee would equal 3.75% of the implied equity value of Six Flags, Cedar Fair would be able to solicit and entertain competing proposals, and the Cedar Fair Board would be able to change its recommendation in favor of the transaction, under certain circumstances. The revised draft also deleted Six Flags’ proposal with respect to the composition of the committees of the board of the combined company.

On October 20, 2023, the Six Flags Board held a special board meeting by video conference, with members of Six Flags senior management and representatives of Kirkland and Goldman Sachs in attendance. Members of Six Flags senior management discussed with the Six Flags Board the potential strategic benefits that could result from the potential transaction, including that the potential transaction would create (i) a combined company with expanded and diversified experiences for guests, (ii) a stronger balance sheet enabling increased investment and improved guest experiences, (iii) a larger geographical footprint, which would mitigate weather-related seasonality, and (iv) the opportunity to achieve synergies, which Six Flags and Cedar Fair management estimated could reach or exceed $200 million annually by 2027, and the ability of the combined company to achieve such strategic benefits. Members of the Six Flags Board also discussed potential risks, including execution and integration risks, in connection with the potential transaction. Representatives from Kirkland and the Six Flags Board discussed the remaining open points in the draft merger agreement, which were primarily social and governance issues, including the roles Messrs. Bassoul and Mick would have at the combined company, in

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addition to open points regarding the size of the termination fee, ultimate control over regulatory decision-making in the event of a disagreement between the parties, and the ability of Cedar Fair to solicit and entertain competing proposals, and of the Cedar Fair Board to change its recommendation in favor of the transaction, under certain circumstances. During the discussion, the Six Flags Board reiterated its view that it was important for Mr. Bassoul to be the Executive Chairman of the board of the combined company and Mr. Mick to be the Chief Integration Officer of the combined company in order to help drive integration efforts, culture alignment and synergy achievement. The Six Flags Board directed Mr. Bassoul to convey this position, along with the Six Flags Board’s positions on the other open terms of the merger agreement, to Messrs. Zimmerman and Hanrahan during a conversation planned for October 22, 2023.

On October 21, 2023, Messrs. Zimmerman and Bassoul had a call where they discussed general status and updates regarding the transaction, and aspects of Mr. Bassoul’s position as Chairman or Executive Chairman of the board of the combined company, including the responsibilities and duties thereof and that, although the position would require business time in the United States, Mr. Bassoul’s primary residence would be in Dubai after the Closing.

On October 22, 2023, Mr. Bassoul met with Messrs. Zimmerman and Hanrahan at the Dallas-Fort Worth airport to discuss their vision for the combined company, the open terms in the merger agreement, including whether the Chairman role would be an executive or non-executive position and the potential name of the combined company, and the companies’ respective cultures and values.

On October 23, 2023, Mr. Bassoul, Mr. Zimmerman and representatives of Kirkland and Weil held a call to discuss the open points in the draft merger agreement. Following discussion, Messrs. Bassoul and Zimmerman agreed upon a number of open points in the draft merger agreement, including that (i) Mr. Bassoul would be the Executive Chairman of the board of the combined company and Mr. Mick would serve a primary integration role at the combined company, (ii) committees of the board of the combined company would consist of an equal number of Six Flags and Cedar Fair designees, and that the chair of the audit committee of the combined company would be designated by Cedar Fair while the chair of the nominating and governance and compensation committees of the combined company would be designated by Six Flags, (iii) Cedar Fair would appoint a lead independent director of the board of the combined company, (iv) Six Flags would be required to pay a termination fee equal to 3.75% of the implied equity value of Six Flags if the merger agreement was terminated under certain circumstances, (v) Cedar Fair would not be able to solicit or entertain competing proposals, and the Cedar Fair Board would not be able to change its recommendation in favor of the transaction and (vi) that Messrs. Bassoul and Zimmerman would jointly resolve any disagreement with respect to regulatory decision-making between the parties.

Also on October 23, 2023, acting at the direction of the Six Flags Board and Cedar Fair, respectively, representatives of Goldman Sachs and Perella Weinberg held a call to discuss pro forma ownership of Six Flags and Cedar Fair equityholders in the combined company, the appropriate exchange ratios for converting Cedar Fair Units and Six Flags Common Stock into shares of common stock of the combined company and the amount of the special dividend that would be required to equalize the consideration value to 50% for each company’s equityholders in the transaction. Consistent with the Six Flags Board’s directives to Goldman Sachs, representatives of Goldman Sachs and Perella Weinberg discussed a pro forma ownership split that would result in Cedar Fair Unitholders owning 51.2% of the combined company and Six Flags Stockholders holding 48.8% of the combined company, along with a special dividend for Six Flags Stockholders prior to the closing of the potential transaction, which special dividend would consist of (i) $1 per share to achieve the intended economics of the transaction and (ii) an additional amount per share to reflect the per unit amount of any quarterly distributions declared or paid by Cedar Fair with respect to Cedar Fair Units with a record date between signing and closing of the potential transaction, and agreed to continue discussing the exchange ratios.

On October 24, 2023, the Cedar Fair Board held a regularly scheduled board meeting at the Dallas-Fort Worth airport to discuss the potential transaction. Messrs. Bassoul and Mick attended a portion of the meeting, during which they discussed their vision for the combined company with the Cedar Fair Board.

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Also on October 24, 2023, representatives of Kirkland sent representatives of Weil a revised draft merger agreement reflecting the parties’ agreement on the terms discussed between Messrs. Bassoul and Zimmerman the previous day, along with initial drafts of the certificate of incorporation and bylaws for the combined company.

On October 25, 2023, members of Six Flags management held a legal due diligence call by video conference with questions led by representatives of Weil and attendance by Kirkland and Cedar Fair. Additionally, on October 25, 2023, members of Cedar Fair management held a legal due diligence call by video conference with questions led by representatives of Kirkland and attendance by Weil and Six Flags.

Between October 25, 2023 and October 31, 2023, representatives of Goldman Sachs, Perella Weinberg, Kirkland and Weil continued discussing the exchange ratios.

On October 26, 2023, the Six Flags Board held a special board meeting by video conference, with members of Six Flags senior management and representatives of Kirkland and Goldman Sachs in attendance. Representatives of Kirkland updated the Six Flags Board on the proposed terms of the potential transaction, including social and governance terms, deal protection provisions and regulatory efforts provisions. Representatives of Kirkland noted that the draft merger agreement provided that the common stock of the combined company would be owned 51.2% by former Cedar Fair Unitholders and 48.8% by former Six Flags Stockholders, with a special dividend to be paid to Six Flags Stockholders prior to the Closing, which special dividend would equal (i) $1 per share to equalize consideration value to 50% for each company’s equityholders plus (ii) an additional per share amount reflecting the per unit amount of any quarterly distributions declared or paid by Cedar Fair with respect to Cedar Fair Units with a record date between signing and closing of the potential transaction. Representatives of Kirkland also discussed with the Six Flags Board certain regulatory considerations in connection with the potential transaction and the anticipated timeline between signing and Closing. Representatives of Goldman Sachs reviewed its preliminary financial analyses with the Six Flags Board, including a review of the Six Flags Standalone Projections, the Cedar Fair Standalone Projections and the progress made on developing the combined company model which would take into account potential synergies in connection with the potential transaction.

Between October 26, 2023 and November 1, 2023, representatives of Weil and representatives of Kirkland exchanged multiple revised drafts of the merger agreement, disclosure schedules and organizational documents for the combined company, including descriptions for certain roles at the combined company, including the Executive Chairman and lead independent director roles. During this time, key open points included whether the combined company would have a classified board and whether the governance documents of the combined company would provide that any merger of the combined company would require a supermajority stockholder approval, each consistent with Cedar Fair’s organizational documents.

On October 29, 2023, the Six Flags Board held a special board meeting by video conference, with members of Six Flags senior management and representatives of Kirkland and Goldman Sachs in attendance. During the meeting, representatives of Kirkland reviewed with Six Flags directors the fiduciary duties of the Six Flags Board in connection with the potential transaction with Cedar Fair. Representatives of Kirkland described to the Six Flags Board the key terms of the draft merger agreement, including pro forma ownership, the terms of the special dividend, treatment of equity awards, social and governance issues, including the organizational documents of the combined company and the roles of certain Six Flags management members in the combined company, closing conditions, regulatory efforts provisions and non-solicitation and deal protection provisions, including the termination fee (equal to 3.75% of Six Flags’ equity value) payable by Six Flags under certain circumstances. Representatives of Kirkland and Goldman Sachs discussed with the Six Flags Board other considerations and risks in connection with the potential transaction, including regulatory and financing considerations, execution risks and the open points regarding the governance of the combined company and relevant considerations. Following discussion regarding the merits and risks of including a classified board at the combined company, the Six Flags Board expressed willingness to consider Cedar Fair’s request to include a classified board at the combined company, consistent with Cedar Fair’s current board structure. Members of Six

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Flags senior management and representatives of Kirkland described refinancing plans in connection with the potential transaction and provided an overview to the Six Flags Board of the legal, financial, tax and accounting diligence conducted in connection with the potential transaction. Following these discussions, at the invitation of the Six Flags Board, Messrs. Zimmerman and Witherow joined the meeting to discuss their vision for the combined company with the Six Flags Board.

On October 31, 2023, at the direction of Six Flags and Cedar Fair, representatives of Goldman Sachs, Perella Weinberg, Kirkland and Weil met telephonically to discuss the exchange ratio and certain related provisions of the draft merger agreement. Subsequently that day, the parties agreed on an exchange ratio of 0.5800 shares of the combined company per share of Six Flags Common Stock.

Also on October 31, 2023, the Six Flags Board, excluding Mr. Bassoul, held a special board meeting by video conference to discuss the treatment of Messrs. Bassoul’s and Mick’s equity awards and post-Closing compensation packages in light of the fact that both had expressed willingness to step down from their current roles and continue with the combined company in positions deemed appropriate by the Six Flags Board. During the meeting, the chair of the compensation committee of the Six Flags Board provided a summary to the Six Flags Board of the recommendation of the compensation committee regarding the treatment of the equity awards of Messrs. Bassoul and Mick in connection with the potential transaction and the compensation packages for Messrs. Bassoul and Mick in their respective roles of Executive Chairman and Chief Integration Officer of the combined company. Following discussion, the Six Flags Board approved the proposal recommended by the compensation committee of the Six Flags Board.

On November 1, 2023, the Six Flags Board held a special board meeting by video conference, with members of Six Flags senior management and representatives of Kirkland and Goldman Sachs in attendance. Representatives from Kirkland updated the Six Flags Board regarding the finalized terms of the proposed merger agreement, including the terms of the certificate of incorporation and bylaws of the combined company. Representatives of Goldman Sachs then reviewed its financial analysis of the potential transaction and delivered to the Six Flags Board an oral opinion, which was confirmed by delivery of a written opinion, dated November 2, 2023, to the effect that, as of the date of its written opinion and based upon and subject to the factors and assumptions set forth therein, and taking into account the Cedar Fair Mergers, the Six Flags Aggregate Consideration to be paid to the holders (other than Cedar Fair and its affiliates) of Six Flags Common Stock pursuant to the Merger Agreement is fair from a financial point of view to such holders. Following discussion, including as to the matters described below in the section entitled “The Mergers — Recommendation of the Six Flags Board and Six Flags’ Reasons for the Merger”, the Six Flags Board unanimously (i) determined that the merger agreement and the Six Flags Merger were advisable and fair to, and in the best interests of, Six Flags and the Six Flags Stockholders, (ii) approved (A) the form, terms and conditions of the merger agreement, (B) the execution, delivery and performance by the Six Flags thereof and (C) subject to the adoption of the merger agreement at the Six Flags Special Meeting, the consummation of the transactions contemplated by the merger agreement, including the Six Flags Merger and the declaration of the Special Dividend, (iii) resolved to recommend that the Six Flags Stockholders adopt the merger agreement on the terms and subject to the conditions set forth in the merger agreement and (iv) directed that the adoption of the merger agreement be submitted to the Six Flags Stockholders at the Six Flags special meeting.

On November 2, 2023, Six Flags and Cedar Fair executed the Merger Agreement. Six Flags and Cedar Fair then issued a joint press release announcing the parties’ entry into the Merger Agreement and held a joint investor call.

The Six Flags Special Meeting of Stockholders

Six Flags has agreed to take all action necessary in accordance with applicable laws and the organizational documents of Six Flags to duly give notice of, convene and hold a meeting of its stockholders for the purpose of obtaining the approval of the Merger Agreement Proposal by Six Flags Stockholders, to be held as promptly as

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practicable after the clearance of this proxy statement/prospectus by the SEC and a registration statement, of which this proxy statement/prospectus forms a part, being declared effective by the SEC. Unless there has been a Six Flags Recommendation Change in accordance with the Merger Agreement, the Six Flags Board must recommend that the Six Flags Stockholders vote in favor of the Merger Agreement Proposal and this proxy statement/prospectus is required to include such recommendation of the Six Flags Board. Pursuant to the Merger Agreement, a “Six Flags Recommendation Change” refers to actions of the Six Flags Board to (i) withdraw, qualify or modify, or propose publicly to withdraw, qualify or modify or fail to make, in each case in a manner adverse to Cedar Fair, the recommendation by the Six Flags Board or such committee of the Six Flags Merger or the Merger Agreement and/or (ii) approve or recommend, or propose publicly to approve or recommend, any Six Flags Alternative Transaction.

Six Flags may only postpone or adjourn the Six Flags Special Meeting (i) to solicit additional proxies for the purpose of obtaining the required Six Flags Stockholder Approval, (ii) for the absence of a quorum, and (iii) to allow reasonable additional time for the filing or mailing of any supplemental or amended disclosure that Six Flags has determined after consultation with outside legal counsel is reasonably likely to be required under applicable law and for such supplemental or amended disclosure to be disseminated and reviewed by Six Flags Stockholders prior to the Six Flags Special Meeting. Notwithstanding the foregoing, Six Flags shall postpone or adjourn the Six Flags Special Meeting up to two times for up to 30 days each time upon the mutual decision of Six Flags and Cedar Fair, each acting reasonably.

What Stockholders and Unitholders Will Receive in the Mergers and Potential Adjustments

Six Flags Merger Consideration. Subject to the terms and conditions set forth in the Merger Agreement, each Eligible Share outstanding immediately prior to the Closing Effective Time will be converted automatically into the right to receive 0.5800 shares of CopperSteel Common Stock, as may be adjusted pursuant to the Merger Agreement. Six Flags Stockholders will not receive any fractional shares of CopperSteel Common Stock in the Mergers. Instead, Six Flags Stockholders will receive cash in lieu of any fractional shares of CopperSteel Common Stock that they would otherwise have been entitled to receive.

Cedar Fair Merger Consideration. Subject to the terms and conditions set forth in the Merger Agreement, each Cedar Fair Unit issued and outstanding immediately prior to the Cedar Fair First Merger Effective Time (excluding (a) units held in the treasury of Cedar Fair or owned by the Cedar Fair General Partner and (b) any Cedar Fair Restricted Units) will be converted into the right to receive one (1) share of CopperSteel Common Stock, as may be adjusted subject to the terms and conditions set forth in the Merger Agreement. Cedar Fair Unitholders will not receive any fractional shares of CopperSteel Common Stock in the Mergers. Instead, Cedar Fair Unitholders will receive cash in lieu of any fractional shares of CopperSteel Common Stock that they would otherwise have been entitled to receive.

The Merger Agreement contains provisions that, in the event the outstanding Cedar Fair Units or shares of Six Flags Common Stock are, prior to the Closing, changed into a different number of units or shares, as applicable, by reason of any reclassification, recapitalization, split-up, combination, exchange of units or shares, dividend payable in stock or other securities or other similar transaction, the Cedar Fair Merger Consideration or the Six Flags Merger Consideration and the Cedar Fair Exchange Ratio or Six Flags Exchange Ratio or the amount of the Special Dividend will be adjusted to provide the holders of Cedar Fair Units, Six Flags Common Stock, Cedar Fair Equity Awards and Six Flags Equity Awards the same economic effect contemplated by the Merger Agreement prior to any such transaction, and in any event to ensure that the Cedar Fair Merger Consideration amounts to the aggregate number of shares of CopperSteel Common Stock representing at least 51.01% of the voting power of all issued and outstanding shares of CopperSteel Common Stock immediately following the Closing Effective Time.

The high and low trading prices for the Six Flags Common Stock as of November 2, 2023, the last trading day immediately before the public announcement of the Mergers, were $22.70 and $20.62, respectively. The high

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and low trading prices for the Cedar Fair Units as of November 2, 2023, the last trading day immediately before the public announcement of the merger, were $38.22 and $34.53, respectively. We urge you to obtain current market quotations before voting your shares.

Interests of Certain Six Flags Directors and Executive Officers in the Mergers

In considering the recommendation of the Six Flags Board with respect to the Merger Agreement, Six Flags Stockholders should be aware that, aside from their interests as Six Flags Stockholders, Six Flags’ directors and executive officers have interests in the Mergers that may be different from, or in addition to, the interests of Six Flags Stockholders generally, including, but not limited to, the treatment of outstanding Six Flags Equity Awards pursuant to the Merger Agreement, potential severance and other benefits upon a qualifying termination of employment in connection with the Mergers, eligibility, in the case of Mr. Bassoul, for a cash transaction bonus, eligibility for payment of an annual bonus in respect of 2023 and (depending on the timing of Closing) eligibility for payment of a pro-rated annual bonus in respect of 2024, and rights to ongoing indemnification and insurance coverage. The Six Flags Board was aware of and considered these potential interests, among other matters, in evaluating and negotiating the Merger Agreement and the transactions contemplated therein, in approving the Mergers and in recommending the approval of the Merger Agreement Proposal.

Treatment of Six Flags Equity Awards Held by Six Flags Executive Officers

With respect to Six Flags RSU Awards and Six Flags PSU Awards held by Messrs. Bassoul and Mick, the only two executive officers of Six Flags, the treatment of Six Flags RSU Awards and Six Flags PSU Awards described in the section entitled “The Merger Agreement — Treatment of Six Flags Equity Awards in the Mergers” will not apply, and Messrs. Bassoul and Mick’s Six Flags RSU Awards and Six Flags PSU Awards will be treated as follows at the Closing Effective Time (except as otherwise described below in the section entitled “The Mergers — Interests of Certain Six Flags Directors and Executive Officers in the Mergers — 280G Mitigation”):

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The table below sets forth (i) the number of Six Flags RSU Awards held by Messrs. Bassoul and Mick that are unvested as of January 17, 2024, (ii) the number of Six Flags PSU Awards held by Messrs. Bassoul and Mick that will vest at the Closing Effective Time pursuant to the Merger Agreement and (iii) the estimated value of those awards (on a pre-tax basis). Such amounts have been calculated assuming a price per share of Six Flags Common Stock of $23.47, which is equal to the average closing price per share of Six Flags Common Stock over the first five business days following the announcement of the Merger Agreement on November 2, 2023. The actual value realized with respect to any Six Flags RSU Awards and Six Flags PSU Awards cannot be determined with any certainty until such Six Flags Equity Awards are settled.

See the section below entitled “The Mergers— Quantification of Potential Payments and Benefits to Six Flags’ Named Executive Officers in Connection with the Mergers” in this proxy statement/prospectus for an estimate of the amounts that would become payable to each Six Flags named executive officer in respect of their unvested Six Flags Equity Awards. See also the section below entitled “The Mergers — Interests of Certain Six Flags Directors and Executive Officers in the Mergers — 280G Mitigation” for a description of certain actions taken in respect of Messrs. Bassoul and Mick’s Six Flags RSU Awards and Six Flags PSU Awards.

Treatment of Six Flags Deferred Share Unit Awards and Six Flags Restricted Shares Held by Six Flags Non-Employee Directors

Pursuant to the Merger Agreement, each Six Flags Deferred Share Unit Award held by Six Flags non-employee directors, whether vested or unvested, that is outstanding immediately prior to the Closing Effective Time will fully vest and be converted at the Closing Effective Time into a number of shares of fully vested CopperSteel Common Stock based on the Six Flags Exchange Ratio. All Six Flags Deferred Share Unit Awards and Six Flags Restricted Shares held by Six Flags non-employee directors will be eligible for payment of the Special Dividend. Pursuant to the Merger Agreement, each Six Flags Restricted Share held by Six Flags non-employee directors will fully vest (or will be amended so that they vest) at the Closing Effective Time, subject to the applicable non-employee director’s continued service on the Six Flags Board through the Closing Effective Time.

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The table below sets forth (i) the Six Flags Restricted Shares and/or Six Flags Deferred Share Unit Awards held by each Six Flags non-employee director that are unvested as of January 17, 2024; and (ii) the estimated value of those awards (on a pre-tax basis). Such amounts have been calculated assuming a price per share of Six Flags Common Stock of $23.47, which is equal to the average closing price per share of Six Flags Common Stock over the first five business days following the announcement of the Mergers on November 2, 2023. The actual value realized with respect to any Six Flags Restricted Shares and/or Six Flags Deferred Share Unit Awards cannot be determined with any certainty until such Six Flags Equity Awards are settled. Mr. Ruchim does not hold any Six Flags Restricted Shares or Six Flags Deferred Share Unit Awards as he previously advised the Six Flags Board that he did not wish to receive any director fees because his interests were already highly aligned with Six Flags’ Stockholders due to his position with H Partners, LP, a significant stockholder of Six Flags Common Stock which owned approximately 13.64% of the outstanding Six Flags Common Stock as of the date of the Merger Agreement.

Agreements with Six Flags Executive Officers

Messrs. Bassoul and Mick are currently employed pursuant to written employment agreements with Six Flags effective as of November 14, 2021 and May 31, 2022, respectively. Pursuant to the Merger Agreement, prior to the Closing Effective Time, Messrs. Bassoul and Mick will each enter into an amended and restated employment agreement with CopperSteel, to serve as Executive Chairman of CopperSteel (in the case of Mr. Bassoul) and Chief Integration Officer (in the case of Mr. Mick), in each case, that will be effective as of the Closing Effective Time and are expected to provide for the following (except as otherwise described in the section below entitled “The Mergers — Interests of Certain Six Flags Directors and Executive Officers in the Mergers — 280G Mitigation”):

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Under their existing employment agreements with Six Flags, Messrs. Bassoul and Mick are each expected to remain subject to restrictions relating to the use of confidential information, competing against Six Flags and soliciting customers or employees of Six Flags, and non-disparagement.

280G Mitigation

In order to mitigate the possible impact of Sections 280G and 4999 of the Code on Messrs. Bassoul and Mick and the Company, in connection with the Mergers, the Six Flags Board approved the following, effective as of December 20, 2023:

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Six Flags 2023 and 2024 Annual Bonuses

Pursuant to the Merger Agreement, Messrs. Bassoul and Mick are each entitled to receive payment in respect of their 2023 annual bonuses at the greater of target and actual levels of performance (calculated in accordance with the applicable Six Flags bonus program), to be paid at the time annual bonuses are ordinarily paid. For details regarding the payment of such 2023 annual bonuses, see the section above entitled “The Mergers — Interests of Certain Six Flags Directors and Executive Officers in the Mergers — 280G Mitigation”.

Pursuant to the Merger Agreement, Six Flags may adopt and administer annual bonus, commission and incentive plans, and may establish annual incentive targets and performance goals pursuant to its annual bonus, commission and incentive plans in the ordinary course, in respect of the fiscal year ending December 31, 2024 (subject to the terms of the Merger Agreement) if the Closing Effective Time has not occurred by the time such targets and goals would be established in the ordinary course of business. In connection with the foregoing, Six Flags may pay a pro-rata portion of unpaid annual cash bonus and incentive amounts, including to the executive officers, at the greater of actual and target performance, in respect of the portion of fiscal year 2024 that has elapsed as of the Closing Date.

Indemnification of Six Flags Directors and Officers in the Mergers

The Merger Agreement requires CopperSteel to indemnify and hold harmless each individual who is as of the date of the Merger Agreement or becomes prior to the Closing Effective Time, a director or officer of Cedar Fair, the Cedar Fair General Partner or Six Flags and any of their respective subsidiaries, and each person who was serving as a director, officer of another person at the request of Cedar Fair or Six Flags and any of their respective subsidiaries, each referred to as an “Indemnified Party”, against all claims, losses, liabilities, damages, judgments, inquiries, fines and reasonable fees, costs and expenses, including attorneys’ fees and disbursements, incurred in connection with any claim, action, suit or proceeding, whether civil, criminal, administrative or investigative (including with respect to matters existing or occurring at or prior to the Closing Effective Time (including the Merger Agreement and the transactions and actions contemplated thereby)) arising out of or pertaining to the fact that the Indemnified Party is or was an officer or director of Cedar Fair or the Cedar Fair General Partner or Six Flags, as applicable, or any of their respective subsidiaries or is or was serving at the request of Cedar Fair or Six Flags, as applicable, or any of their respective subsidiaries as a director, officer or employee of another person or in respect of any acts or omissions in their capacities as such directors, officers or employees occurring prior to the Closing Effective Time, whether asserted or claimed prior to, at or after the Closing Effective Time, to the same extent as such indemnified parties were indemnified as of the date of the Merger Agreement pursuant to the organizational documents of Cedar Fair, Cedar Fair General Partner, or Six Flags or any of their respective subsidiaries, as applicable, or any indemnification agreements in existence as of the date of the Merger Agreement.

Each Indemnified Party will be entitled to advancement of expenses incurred in the defense of any such claim, action, suit or proceeding from CopperSteel to the same extent as such Indemnified Parties are entitled to advance of expenses as of the date of the Merger Agreement by Cedar Fair pursuant to the Cedar Fair Partnership Agreement or the governing or organizational documents of any subsidiary of Cedar Fair or the Cedar Fair General Partner, or by Six Flags pursuant to the Six Flags Certificate of Incorporation, the Six Flags Bylaws or the governing or organizational documents of any subsidiary of Six Flags, as applicable, and any indemnification agreements in existence as of the date of the Merger Agreement; however, any person to whom expenses are advanced provides an undertaking, if and only to the extent required by the DGCL, the Cedar Fair Partnership

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Agreement or the Certificate of Incorporation or By-laws of the Cedar Fair General Partner, or the Six Flags Certificate of Incorporation or the Six Flags Bylaws, as applicable, and any indemnification agreements in existence as of the date of the Merger Agreement, to repay such advances if it is ultimately determined that such person is not entitled to indemnification. CopperSteel will, and will cause its subsidiaries to, cooperate in the defense of any such matter.

The Merger Agreement also requires CopperSteel for six years following the Closing Effective Time either to cause to be maintained the policies of directors’ and officers’ liability insurance and fiduciary liability insurance currently maintained by each of Six Flags and Cedar Fair and any of their subsidiaries or to provide substitute policies for not less than the existing coverage and having other terms not less favorable to the insured persons, except that in no event will CopperSteel be required to pay for each maintained or substitute policy an annual premium greater than 300% of the annual premium paid by Six Flags and Cedar Fair, as applicable, for such insurance for the prior 12 months, referred to as the “Cedar Fair Maximum Amount” with respect to Cedar Fair and the “Six Flags Maximum Amount” with respect to Six Flags. Each of Six Flags and Cedar Fair may obtain a six-year “tail” policy under such party’s existing directors and officers insurance policy in lieu of the foregoing, in each case for a cost not to exceed the Cedar Fair Maximum Amount or Six Flags Maximum Amount, as applicable.

Treatment of Cedar Fair Equity Awards

Cedar Fair Restricted Units

At the Cedar Fair First Merger Effective Time, each outstanding Cedar Fair Restricted Unit will be converted into a number of CopperSteel Restricted Shares, equal to the product (rounded up to the nearest whole number) of (x) one (1) and (y) the Cedar Fair Exchange Ratio. Each CopperSteel Restricted Share will continue to be governed by the same terms and conditions (including vesting conditions and forfeiture terms and terms relating to dividend or dividend equivalent rights) as were applicable to the corresponding Cedar Fair Restricted Unit immediately prior to the Cedar Fair First Merger Effective Time. Any amounts relating to dividend or dividend equivalent rights, if any, granted in respect of such Cedar Fair Restricted Unit that are accrued or credited and unpaid as of the Cedar Fair First Merger Effective Time, will be carried over and paid if and when required in accordance with the terms that were applicable to the corresponding Cedar Fair Restricted Unit immediately prior to the Cedar Fair First Merger Effective Time.

Cedar Fair Phantom Units

At the Cedar Fair First Merger Effective Time, each outstanding Cedar Fair Phantom Unit, whether vested or unvested, will be converted into a number of CopperSteel RSU Awards, equal to the product (rounded up to the nearest whole number) of (x) one (1) and (y) the Cedar Fair Exchange Ratio. Each CopperSteel RSU Award will continue to be governed by the same terms and conditions (including vesting conditions and forfeiture terms and terms relating to dividend or dividend equivalent rights) as were applicable to the corresponding Cedar Fair Phantom Unit immediately prior to the Cedar Fair First Merger Effective Time. Any amounts relating to dividend or dividend equivalent rights, if any, granted in respect of such Cedar Fair Phantom Unit that are accrued or credited and unpaid as of the Cedar Fair First Merger Effective Time, will be carried over and paid if and when required in accordance with the terms that were applicable to the corresponding Cedar Fair Phantom Unit immediately prior to the Cedar Fair First Merger Effective Time.

Cedar Fair Performance Units

At the Cedar Fair First Merger Effective Time, each outstanding Cedar Fair Performance Unit, whether vested or unvested, will be converted into a CopperSteel RSU Award. The number of shares of CopperSteel Common Stock subject to each CopperSteel RSU Award will equal the product (rounded up to the nearest whole number) of (A) the number of Cedar Fair Units subject to such Cedar Fair Performance Unit determined in

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accordance with the immediately following sentence and (B) the Cedar Fair Exchange Ratio. For purposes of the immediately preceding sentence, the number of Cedar Fair Units subject to such Cedar Fair Performance Units shall be determined based on (x) for Cedar Fair Performance Units that are subject to a performance period (or portion thereof) in which the Closing Effective Time occurs, the higher of target performance and actual performance through the Cedar Fair First Merger Effective Time as reasonably determined by the Cedar Fair Board or the appropriate committee thereof and (y) for Cedar Fair Performance Units that are subject to any performance period (or portion thereof) that begins after the Closing Effective Time, target performance. Each CopperSteel RSU Award will continue to be governed by the same terms and conditions (including vesting conditions and forfeiture terms and terms relating to dividend or dividend equivalent rights) as were applicable to the corresponding Cedar Fair Performance Unit immediately prior to the Cedar Fair First Merger Effective Time, except that they will no longer be subject to performance-vesting conditions. Any amounts relating to dividend or dividend equivalent rights, if any, granted in respect of such Cedar Fair Performance Units that are accrued or credited and unpaid as of the Cedar Fair First Merger Effective Time, will be carried over and paid if and when required in accordance with the terms that were applicable to the corresponding Cedar Fair Performance Units immediately prior to the Cedar Fair First Merger Effective Time.

Cedar Fair Unit-Settled Deferred Units

At the Cedar Fair First Merger Effective Time, each outstanding Cedar Fair Unit-Settled Deferred Unit will be cancelled and entitle the holder thereof to receive (without interest), as soon as reasonably practicable after the Cedar Fair First Merger Effective Time (but in any event no later than ten business days thereafter), (A) a number of fully vested shares of CopperSteel Common Stock equal to the product (rounded up to the nearest whole number) of (x) the number of Cedar Fair Units underlying the Cedar Fair Unit-Settled Deferred Unit Award immediately prior to the Cedar Fair First Merger Effective Time and (y) the Cedar Fair Exchange Ratio, and (B) any amounts relating to dividend or dividend equivalent rights, if any, granted in respect of such Cedar Fair Unit-Settled Deferred Unit that are accrued or credited and unpaid as of the Cedar Fair First Merger Effective Time, less applicable taxes required to be withheld with respect thereto.

Cedar Fair Cash-Settled Deferred Units

At the Cedar Fair First Merger Effective Time, each outstanding Cedar Fair Cash-Settled Deferred Unit will be cancelled and entitle the holder thereof to receive (without interest), as soon as reasonably practicable after the Cedar Fair First Merger Effective Time (but in any event no later than ten business days thereafter), (A) a cash payment equal to the product (rounded up to the nearest whole number) of (x) the number of Cedar Fair Units underlying the Cedar Fair Cash-Settled Deferred Unit immediately prior to the Cedar Fair First Merger Effective Time and (y) the closing price of a Cedar Fair Unit on the New York Stock Exchange as reported by Bloomberg L.P. on the day immediately prior to the Closing Date, plus (B) any amounts relating to dividend or dividend equivalent rights, if any, granted in respect of such Cedar Fair Cash-Settled Deferred Unit that are accrued or credited and unpaid as of the Cedar Fair First Merger Effective Time, less applicable taxes required to be withheld with respect thereto.

Cedar Fair Transaction-Based Performance Units

On December 4, 2023, the Cedar Fair Board approved and granted awards of transaction-based Cedar Fair Performance Units to certain members of Cedar Fair’s management team in recognition of their efforts in connection with the Mergers. These awards, which upon the Cedar Fair First Merger Effective Time, will convert into CopperSteel RSU Awards as described above in the section entitled “The Mergers — Treatment of Cedar Fair Equity Awards – Cedar Fair Performance Units” will vest and be payable as to 50% of the equity subject to the awards on the 12 month anniversary of the grant date, with the remaining 50% of the equity subject to the awards to vest and be payable on the 18 month anniversary of the grant date, subject, in each case, to the occurrence of the Closing Effective Time and the recipient’s continued employment with CopperSteel or one of its affiliates through each payment date. The number of transaction-based Cedar Fair Performance Units awarded

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to the officers of Cedar Fair are as follows: Mr. Zimmerman (91,058); Mr. Fisher (50,994); Mr. Witherow (50,994) and Mr. Nurse (25,497).

Quantification of Potential Payments and Benefits to Six Flags’ Named Executive Officers in Connection with the Mergers

This section sets forth the information required by Item 402(t) of Regulation S-K regarding the compensation arrangements of each of Six Flags’ named executive officers that is based on or otherwise relates to the Mergers and that will or may become payable to Six Flags’ named executive officers at the Closing Effective Time or upon a qualifying termination of employment that occurs following the Closing Effective Time, assuming (i) the Closing Effective Time occurs on December 15, 2023 (which is the latest practicable date prior to the filing of this proxy statement/prospectus), (ii) each of the Six Flags named executive officers experiences a qualifying termination on such date, (iii) the Six Flags named executive officers’ respective base salaries and target annual bonuses remain unchanged from those that were in effect as of the date of this filing, (iv) Six Flags RSU Awards and Six Flags PSU Awards held by Six Flags’ named executive officers that are outstanding as of January 17, 2024, remain outstanding and unvested as of immediately prior to the Closing Effective Time, (v) for purposes of determining the value of Six Flags RSU Awards and Six Flags PSU Awards, the value of a share of Six Flags Common Stock is $23.47, which is equal to the average closing price per share of Six Flags Common Stock over the first five business days following the announcement of the Mergers on November 2, 2023, (vi) no Six Flags named executive officer receives any additional equity grants prior to the Closing Effective Time, and (vii) each Six Flags named executive officer has properly executed any required releases and complied with all requirements (including any applicable restrictive covenants) necessary in order to receive the payments and benefits described below.

The payments described in the table below are made pursuant to new employment arrangements with Messrs. Bassoul and Mick to be entered into with CopperSteel to be effective as of the Closing Effective Time, as described above in the section entitled “The Mergers — Interests of Certain Six Flags Directors and Executive Officers in the Mergers — Agreements with Six Flags Executive Officers”, and do not describe the actions described above in the section entitled “The Mergers — Interests of Certain Six Flags Directors and Executive Officers in the Mergers — 280G Mitigation”.

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Ownership of CopperSteel Common Stock After the Mergers

Following the Closing Effective Time, Cedar Fair Unitholders will own approximately 51.2% of the outstanding shares of CopperSteel Common Stock and the Six Flags Stockholders will own approximately 48.8% of the outstanding shares of CopperSteel Common Stock.

Voting and Support Agreement

Concurrently with the execution of the Merger Agreement, on November 2, 2023, Cedar Fair, H Partners, and, solely for purposes of certain sections therein, Six Flags, entered into the Voting and Support Agreement, pursuant to which H Partners, a significant stockholder of Six Flags Common Stock which owned approximately

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13.64% of the outstanding Six Flags Common Stock as of the date of the Merger Agreement, agreed to, among other things, and subject to certain exceptions, vote (or cause to be voted), in person or by proxy at the Six Flags Special Meeting, all shares of Six Flags Common Stock beneficially owned by H Partners as of the date of the Voting and Support Agreement (or thereafter acquired):

H Partners also agreed to appear in person or by proxy at each meeting or otherwise cause all of its shares to be counted as present for purposes of calculating a quorum.

Notwithstanding the foregoing, in the event that there is any amendment to the Merger Agreement which (w) reduces or changes the form of the Six Flags Merger Consideration, (x) increases or changes the form of Cedar Fair Merger Consideration, (y) changes the payment terms of the Six Flags Merger Consideration in any respect adverse to the holders of shares of Six Flags Common Stock, or (z) effects any change that is materially adverse to the holders of shares of Six Flags Common Stock, H Partners will have no obligation to vote any of its shares in accordance with the Voting and Support Agreement in favor of the Mergers or with respect to the Merger Agreement as so amended or take any other action under the Merger Agreement; and provided, further, that H Partners will retain at all times the right to vote its shares in H Partners’ sole discretion, and without any other limitation, on any matters other than those set forth above and in the Voting and Support Agreement that are at any time or from time to time presented for consideration to Six Flags’ Stockholders generally.

Six Flags consented to H Partners’ entrance into the Voting and Support Agreement and waived its rights with respect to certain sections of the Cooperation Agreement. The Voting and Support Agreement provides that Six Flags and H Partners will enter into an amendment to the Cooperation Agreement to have the Cooperation Agreement terminate at the Closing Effective Time.

The Voting and Support Agreement will terminate automatically upon the earliest to occur of (a) the date on which the Mergers become effective, (b) the date on which the Merger Agreement is validly terminated, (c) the Outside Date, and (d) the date on which the parties agree in writing to terminate the Voting and Support Agreement.

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Opinion of Six Flags’ Financial Advisor

Opinion of Six Flags’ Financial Advisor

Goldman Sachs rendered its opinion to the Six Flags Board that, as of November 2, 2023 and based upon and subject to the factors and assumptions set forth therein, and taking into account the Cedar Fair Mergers, the Six Flags Aggregate Consideration to be paid to the holders (other than Cedar Fair and its affiliates) of Six Flags Common Stock pursuant to the Merger Agreement is fair from a financial point of view to such holders.

The full text of the written opinion of Goldman Sachs, dated November 2, 2023, which sets forth assumptions made, procedures followed, matters considered and limitations on the review undertaken in connection with the opinion, is attached as Annex B. Goldman Sachs provided advisory services and its opinion for the information and assistance of the Six Flags Board in connection with its consideration of the transactions contemplated by the Merger Agreement. Goldman Sachs’ opinion is not a recommendation as to how any holder of Six Flags Common Stock should vote with respect to the transactions contemplated by the Merger Agreement, or any other matter.

In connection with rendering the opinion described above and performing its related financial analyses, Goldman Sachs reviewed, among other things:

Goldman Sachs also held discussions with members of the senior managements of Six Flags and Cedar Fair regarding their assessment of the strategic rationale for, the potential benefits of, the transactions contemplated by the Merger Agreement and the past and current business operations, financial condition, and future prospects of Six Flags, Cedar Fair and CopperSteel; reviewed the reported price and trading activity for the Six Flags Common Stock and the Cedar Fair Units; compared certain financial and stock market information for Six Flags and Cedar Fair with similar information for certain other companies the securities of which are publicly traded; reviewed the financial terms of certain recent business combinations in the theme park industry and in other industries; and performed such other studies and analyses, and considered such other factors, as it deemed appropriate.

For purposes of rendering this opinion, Goldman Sachs, with Six Flags’ consent, relied upon and assumed the accuracy and completeness of all of the financial, legal, regulatory, tax, accounting and other information provided to, discussed with or reviewed by, it, without assuming any responsibility for independent verification thereof. In that regard, Goldman Sachs assumed with Six Flags’ consent that the Forecasts, including the

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Synergies, and the Estimate were reasonably prepared on a basis reflecting the best then available estimates and judgments of the management of Six Flags. Goldman Sachs did not make an independent evaluation or appraisal of the assets and liabilities (including any contingent, derivative or other off-balance-sheet assets and liabilities) of Six Flags, Cedar Fair or CopperSteel or any of their respective subsidiaries and it was not furnished with any such evaluation or appraisal. Goldman Sachs assumed that all governmental, regulatory or other consents and approvals necessary for the consummation of the transactions contemplated by the Merger Agreement will be obtained without any adverse effect on Six Flags, Cedar Fair or CopperSteel or on the expected benefits of the transactions contemplated by the Merger Agreement in any way meaningful to its analysis. Goldman Sachs also assumed that the Special Dividend will be paid to each holder of record of Six Flags Common Stock as of one business day prior to the closing of the Mergers, and that the transactions contemplated by the Merger Agreement will be consummated on the terms set forth in the Merger Agreement, without the waiver or modification of any term or condition the effect of which would be in any way meaningful to its analysis.

Goldman Sachs’ opinion does not address the underlying business decision of Six Flags to engage in the transactions contemplated by the Merger Agreement or the relative merits of such transactions as compared to any strategic alternatives that may be available to Six Flags; nor does it address any legal, regulatory, tax or accounting matters. Goldman Sachs’ opinion addresses only the fairness from a financial point of view, as of the date of the opinion and taking into account the Cedar Fair Mergers, to the holders (other than Cedar Fair and its affiliates) of Six Flags Common Stock of the Six Flags Aggregate Consideration to be paid to such holders pursuant to the Merger Agreement. Goldman Sachs’ opinion does not express any view on, and does not address, any other term or aspect of the Merger Agreement or the transactions contemplated thereby or any term or aspect of any other agreement or instrument contemplated by the Merger Agreement or entered into or amended in connection with the transactions contemplated thereby, including any allocation of the Six Flags Aggregate Consideration, the fairness of the transactions contemplated thereby to, or any consideration received in connection therewith by, the holders of any other class of securities, creditors, or other constituencies of Six Flags; nor as to the fairness of the amount or nature of any compensation to be paid or payable to any of the officers, directors or employees of Six Flags, or class of such persons in connection with the transactions contemplated by the Merger Agreement, whether relative to the Six Flags Aggregate Consideration to be paid to the holders (other than Cedar Fair and its affiliates) of Six Flags Common Stock pursuant to the Merger Agreement and taking into account the Cedar Fair Mergers, or otherwise. Goldman Sachs’ opinion is necessarily based on economic, monetary, market and other condition as in effect on, and the information made available to Goldman Sachs as of, the date of its opinion and Goldman Sachs assumes no responsibility for updating, revising or reaffirming its opinion based on circumstances, developments or events occurring after the date of its opinion. In addition, Goldman Sachs does not express any opinion as to the prices at which shares of Six Flags Common Stock, Cedar Fair Units or CopperSteel Common Stock will trade at any time, as to the potential effects of volatility in the credit, financial and stock markets on Six Flags, Cedar Fair or CopperSteel or the transactions contemplated by the Merger Agreement, or as to the impact of such transactions on the solvency or viability of Six Flags, Cedar Fair or CopperSteel or the ability of Six Flags, Cedar Fair or CopperSteel to pay their respective obligations when they come due. Goldman Sachs’ opinion was approved by a fairness committee of Goldman Sachs.

The following is a summary of the material financial analyses delivered by Goldman Sachs to the Six Flags Board in connection with rendering the opinion described above. The following summary, however, does not purport to be a complete description of the financial analyses performed by Goldman Sachs, nor does the order of analyses described represent relative importance or weight given to those analyses by Goldman Sachs. Some of the summaries of the financial analyses include information presented in tabular format. The tables must be read together with the full text of each summary and are alone not a complete description of Goldman Sachs’ financial analyses. Except as otherwise noted, the following quantitative information, to the extent that it is based on market data, is based on market data as it existed on or before November 1, 2023, the last trading day before the public announcement of the Merger Agreement and is not necessarily indicative of current market conditions.

For purposes of its analyses, at the direction of Six Flags, Goldman Sachs assumed an amount of $1.52 per share of Six Flags Common Stock as the value of the Special Dividend, which amount was derived in accordance with the Merger Agreement based on the timing of the Closing as reflected in the Estimate.

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Illustrative Discounted Cash Flow Analysis

Six Flags Stand-Alone

Using the Forecasts, Goldman Sachs performed an illustrative discounted cash flow analysis on Six Flags to derive a range of illustrative present values per share of Six Flags Common Stock. Using the mid-year convention for discounting cash flows and discount rates ranging from 9.5% to 10.5%, reflecting estimates of Six Flags’ weighted average cost of capital, Goldman Sachs discounted to present value as of September 30, 2023 (i) estimates of unlevered free cash flow (after giving effect to tax-affected net stock-based compensation expenses) for Six Flags for the fourth quarter of fiscal year 2023 and the fiscal years 2024 through 2028 as reflected in the Forecasts, and (ii) a range of illustrative terminal values for Six Flags, which were calculated by applying perpetuity growth rates ranging from 2.0% to 3.0%, to a terminal year estimate of the unlevered free cash flow (after giving effect to tax-affected net stock-based compensation expenses) to be generated by Six Flags, as reflected in the Forecasts (which analysis implied terminal year EBITDA exit multiples ranging from 7.0x to 9.2x). The range of perpetuity growth rates was estimated by Goldman Sachs utilizing its professional judgment and experience, taking into account the Forecasts and market expectations regarding long-term real growth of gross domestic product and inflation. Goldman Sachs derived such discount rates by application of the Capital Asset Pricing Model (“CAPM”), which requires certain company-specific inputs, including Six Flags’ target capital structure weightings, the cost of long-term debt, if any, future applicable marginal cash tax rate and a beta for Six Flags, as well as certain financial metrics for the United States financial markets generally. In addition, assuming discount rates ranging from 9.5% to 10.5%, reflecting estimates of Six Flags’ weighted average cost of capital, Goldman Sachs discounted to present value as of September 30, 2023 the estimated benefits of Six Flags’ net operating losses for the fourth quarter of fiscal year 2023 and the fiscal years 2024 through 2028, as reflected in the Forecasts.

Goldman Sachs derived ranges of illustrative enterprise values for Six Flags by adding the ranges of present values it derived above. Goldman Sachs then subtracted from the range of illustrative enterprise values it derived for Six Flags the amount of Six Flags’ net debt of $2,223 million as of September 30, 2023, as provided by and approved for Goldman Sachs’ use by the management of Six Flags, to derive a range of illustrative equity values for Six Flags. Goldman Sachs then divided the range of illustrative equity values it derived by the number of fully diluted outstanding shares of Six Flags Common Stock as of October 20, 2023, as provided by and approved for Goldman Sachs’ use by the management of Six Flags, using the treasury stock method, to derive a range of illustrative present values per share ranging from $23.00 to $38.16.

Pro Forma Combined Company

Using the Forecasts and the Estimate, including the Synergies and assuming the payment of the Special Dividend, Goldman Sachs performed an illustrative discounted cash flow analysis on the pro forma combined company to derive a range of illustrative present values per share of common stock of the pro forma combined company. Using the mid-year convention for discounting cash flows and discount rates ranging from 9.0% to 10.0%, reflecting estimates of the pro forma combined company’s weighted average cost of capital, Goldman Sachs discounted to present value as of September 30, 2023 (i) estimates of unlevered free cash flow (after giving effect to tax-affected stock-based compensation expenses) for the pro forma combined company for the fourth quarter of fiscal year 2023 and the fiscal years 2024 through 2028 as reflected in the Forecasts, and (ii) a range of illustrative terminal values for the pro forma combined company, which were calculated by applying perpetuity growth rates ranging from 2.0% to 3.0%, to a terminal year estimate of the unlevered free cash flow (after giving effect to tax-affected stock-based compensation expenses) to be generated by the pro forma combined company, as reflected in the Forecasts (which analysis implied terminal year EBITDA exit multiples ranging from 7.5x to 10.0x). The range of perpetuity growth rates was estimated by Goldman Sachs utilizing its professional judgment and experience, taking into account the Forecasts and market expectations regarding long-term real growth of gross domestic product and inflation. Goldman Sachs derived such discount rates by application of the CAPM, which requires certain company-specific inputs, including the pro forma combined company’s target capital structure weightings, the cost of long-term debt, if any, future applicable marginal cash

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tax rate and a beta for the pro forma combined company, as well as certain financial metrics for the United States financial markets generally. In addition, assuming discount rates ranging from 9.0% to 10.0%, reflecting estimates of the pro forma combined company’s weighted average cost of capital, Goldman Sachs discounted to present value as of September 30, 2023 the estimated benefits of the pro forma combined company’s net operating losses for the fourth quarter of fiscal year 2023 and the fiscal years 2024 through 2028, as reflected in the Forecasts.

Goldman Sachs derived ranges of illustrative enterprise values for the pro forma combined company by adding the ranges of present values it derived above. Goldman Sachs then subtracted from the range of illustrative enterprise values it derived for the pro forma combined company by the amount of the pro forma net debt of the combined company as of September 30, 2023, reflecting the payment of the Special Dividend and any distributions paid to the Cedar Fair Unitholders before completion of the Mergers, as provided by and approved for Goldman Sachs’ use by the management of Six Flags, to derive a range of illustrative equity values for the pro forma combined company. Goldman Sachs then divided the range of illustrative pro forma equity values it derived by the pro forma number of fully diluted outstanding shares of the combined company that would be outstanding, as provided by and approved for Goldman Sachs’ use by the management of Six Flags, using the treasury stock method, and then added to such value the estimated amount of the Special Dividend per share, as provided by and approved for Goldman Sachs’ use by the management of Six Flags, to derive a range of illustrative present values per share of Six Flags Common Stock ranging from $30.67 to $48.56.

Illustrative Present Value of Future Share Price Analysis

Six Flags Stand-Alone

Using the Forecasts, Goldman Sachs performed an illustrative analysis of the implied present value of an illustrative future value per share of Six Flags Common Stock. For this analysis, Goldman Sachs first calculated the implied enterprise value for Six Flags as of December 31 for each of the fiscal years 2023, 2024 and 2025, by applying a range of multiples of illustrative next 12 months (“NTM”) enterprise value to adjusted EBITDA (“NTM EV / Adjusted EBITDA”) of 8.0x to 10.0x to estimates of Six Flags’ NTM Adjusted EBITDA for each of the fiscal years 2023, 2024 and 2025. This illustrative range of NTM EV / Adjusted EBITDA multiple estimates was derived by Goldman Sachs utilizing its professional judgment and experience, taking into account current and historical NTM EV / Adjusted EBITDA multiples for Six Flags.

Goldman Sachs then subtracted the amount of Six Flags’ net debt of $2,259 million, $2,092 million and $1,963 million as of December 31 for each of the fiscal years 2023, 2024 and 2025, each as provided by and approved for Goldman Sachs’ use by the management of Six Flags, from the respective implied enterprise values in order to derive a range of illustrative equity values as of December 31 for Six Flags for each of the fiscal years 2023, 2024 and 2025. Goldman Sachs then divided these implied equity values by the projected year-end number of fully diluted outstanding shares of Six Flags Common Stock as of December 31 for each of fiscal years 2023, 2024 and 2025, calculated using information provided by and approved for Goldman Sachs’ use by the management of Six Flags, to derive a range of implied future values per share of Six Flags Common Stock. Goldman Sachs then discounted these implied future equity values per share of Six Flags Common Stock to September 30, 2023, using an illustrative discount rate of 12.1%, reflecting an estimate of Six Flags’ cost of equity. Goldman Sachs derived such discount rate by application of the CAPM, which requires certain company-specific inputs, including a beta for Six Flags, as well as certain financial metrics for the United States financial markets generally. This analysis resulted in a range of implied present values of $25.50 to $45.52 per share of Six Flags Common Stock.

Pro Forma Combined Company

Using the Forecasts and the Estimate, including the Synergies and assuming the payment of the Special Dividend, Goldman Sachs performed an illustrative analysis of the implied present value of an illustrative future

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value per share of common stock of the combined company on a pro forma basis. For this analysis, Goldman Sachs first calculated the implied enterprise value for the pro forma combined company as of December 31 for each of the fiscal years 2023, 2024 and 2025, by applying a range of multiples of illustrative NTM EV / Adjusted EBITDA of 8.0x to 10.0x to estimates of the pro forma combined company’s NTM Adjusted EBITDA for each of the fiscal years 2023, 2024 and 2025. This illustrative range of NTM EV / Adjusted EBITDA multiple estimates was derived by Goldman Sachs utilizing its professional judgment and experience, taking into account current and historical NTM EV / Adjusted EBITDA multiples for Six Flags and Cedar Fair.

Goldman Sachs then subtracted the amount of the pro forma combined company’s net debt as of December 31 for each of the fiscal years 2023, 2024 and 2025, reflecting the payment of the Special Dividend and of any distributions paid to Cedar Fair Unitholders before Closing, each as provided by and approved for Goldman Sachs’ use by the management of Six Flags, from the respective implied enterprise values in order to derive a range of illustrative equity values as of December 31 for the pro forma combined company for each of the fiscal years 2023, 2024 and 2025. Goldman Sachs then divided these implied equity values by the projected year-end number of fully diluted outstanding shares of common stock of the combined company on a pro forma basis for each of the fiscal years 2023, 2024 and 2025, calculated using information provided by and approved for Goldman Sachs’ use by the management of Six Flags, to derive a range of implied future values per share of common stock of the combined company on a pro forma basis. Goldman Sachs then discounted these implied future equity values per share of common stock of the combined company on a pro forma basis to September 30, 2023, using an illustrative discount rate of 11.4%, reflecting an estimate of the pro forma combined company’s cost of equity. Goldman Sachs derived such discount rate by application of the CAPM, which requires certain company-specific inputs, including a beta for the pro forma combined company, as well as certain financial metrics for the United States financial markets generally. Goldman Sachs then added the estimated amount of the Special Dividend per share, as provided by and approved for Goldman Sachs’ use by the management of Six Flags. This analysis resulted in a range of implied present values of $27.11 to $50.26 per share of Six Flags Common Stock.

Selected Transactions Analysis

Goldman Sachs analyzed certain information relating to the following selected transactions in the theme park industry since 2006. For each of the selected transactions, Goldman Sachs calculated and compared the implied EV of the applicable target company based on the consideration paid in the transaction as a multiple of the target company’s LTM EBITDA based on information in public filings, press releases and investor relations documents. While none of the companies that participated in the selected transactions are directly comparable to Six Flags, the companies that participated in the selected transactions are companies with operations that, for the purposes of analysis, may be considered similar to certain of Six Flags’ results, market sizes and product profile.

The following table presents the results of this analysis:

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Based on the results of the foregoing calculations and Goldman Sachs’ professional judgment and experience, Goldman Sachs applied a reference range of EV/LTM Adjusted EBITDA multiples of 8.0x to 12.0x to Six Flags’ LTM adjusted EBITDA as of September 30, 2023, as provided by and approved for Goldman Sachs’ use by the management of Six Flags, to derive a range of implied enterprise values for Six Flags. Goldman Sachs then subtracted the net debt of Six Flags of $2,223 million as of September 30, 2023, as provided by and approved for Goldman Sachs’ use by the management of Six Flags, and divided the result by the number of fully diluted outstanding shares of Six Flags Common Stock as of October 20, 2023, as provided by and approved for Goldman Sachs’ use by the management of Six Flags, to derive a reference range of implied values per share of Six Flags Common Stock of $18.00 to $40.00.

The preparation of a fairness opinion is a complex process and is not necessarily susceptible to partial analysis or summary description. Selecting portions of the analyses or of the summary set forth above, without considering the analyses as a whole, could create an incomplete view of the processes underlying Goldman Sachs’ opinion. In arriving at its fairness determination, Goldman Sachs considered the results of all of its analyses and did not attribute any particular weight to any factor or analysis considered by it. Rather, Goldman Sachs made its determination as to fairness on the basis of its experience and professional judgment after considering the results of all of its analyses. No company or transaction used in the above analyses as a comparison is directly comparable to Six Flags or Cedar Fair or the transactions contemplated by the Merger Agreement. Goldman Sachs prepared these analyses for purposes of Goldman Sachs’ providing its opinion to the Six Flags Board as to the fairness from a financial point of view to the holders (other than Cedar Fair and its affiliates) of Six Flags Common Stock, as of the date of such opinion and taking into account the Cedar Fair Mergers, of the Six Flags Aggregate Consideration to be paid to such holders pursuant to the Merger Agreement. These analyses do not purport to be appraisals nor do they necessarily reflect the prices at which businesses or securities actually may be sold. Analyses based upon forecasts of future results are not necessarily indicative of actual future results, which may be significantly more or less favorable than suggested by these analyses. Because these analyses are inherently subject to uncertainty, being based upon numerous factors or events beyond the control of the parties or their respective advisors, none of Six Flags, Cedar Fair, CopperSteel, Goldman Sachs or any other person assumes responsibility if future results are materially different from those forecast.

The Six Flags Aggregate Consideration was determined through arm’s-length negotiations between Six Flags and Cedar Fair and was approved by the Six Flags Board. Goldman Sachs provided advice to Six Flags during these negotiations. Goldman Sachs did not, however, recommend any specific amount of consideration to Six Flags or its board of directors or that any specific amount of consideration constituted the only appropriate amount of consideration for the transactions contemplated by the Merger Agreement.

As described in the section entitled “The Mergers — Recommendation of the Six Flags Board and Six Flags’ Reasons for the Mergers”, Goldman Sachs’ opinion to the Six Flags Board was one of many factors taken into consideration by the Six Flags Board in making its determination to approve the Merger Agreement. The foregoing summary does not purport to be a complete description of the analyses performed by Goldman Sachs in connection with the fairness opinion and is qualified in its entirety by reference to the written opinion of Goldman Sachs attached as Annex B.

Goldman Sachs and its affiliates are engaged in advisory, underwriting, lending and financing, principal investing, sales and trading, research, investment management and other financial and non-financial activities and services for various persons and entities. Goldman Sachs and its affiliates and employees, and funds or other entities they manage or in which they invest or have other economic interests or with which they co-invest, may at any time purchase, sell, hold or vote long or short positions and investments in securities, derivatives, loans, commodities, currencies, credit default swaps and other financial instruments of Six Flags, Cedar Fair, any of their respective affiliates and third parties, including H Partners, a significant shareholder of Six Flags, and its affiliates and portfolio companies or any currency or commodity that may be involved in the transactions contemplated by the Merger Agreement. Goldman Sachs acted as financial advisor to Six Flags in connection

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with, and participated in certain of the negotiations leading to, the transactions contemplated by the Merger Agreement. With Six Flags’ consent, an affiliate of Goldman Sachs entered into financing commitments and agreements to provide Six Flags and CopperSteel with financing in connection with the consummation of the transactions contemplated by the Merger Agreement, subject to the terms of the agreements governing such financing commitments and agreements. The actual amount of aggregate fees to be received by Goldman Sachs and its affiliates in connection with the Debt Financing will depend upon, among other things, the aggregate amount and form of Debt Financing incurred by Six Flags and CopperSteel. Six Flags estimates that Goldman Sachs and its affiliates will in aggregate receive no more than $12 million in fees in connection with this Debt Financing. Goldman Sachs has provided certain financial advisory and/or underwriting services to Six Flags

and/or its affiliates from time to time for which Goldman Sachs Investment Banking has received, and may receive, compensation, including having acted as a bookrunner with respect to the private offering of Six Flags’ notes due 2031. During the two-year period ended November 2, 2023, Goldman Sachs has recognized compensation for financial advisory and/or underwriting services provided by its Investment Banking Division to Six Flags or its affiliates of approximately $1.3 million. During the two-year period ended November 2, 2023, Goldman Sachs Investment Banking has not been engaged by Cedar Fair or its affiliates to provide financial advisory or underwriting services for which Goldman Sachs has recognized compensation. During the two-year period ended November 2, 2023, Goldman Sachs Investment Banking has not been engaged by H Partners or its affiliates to provide financial advisory or underwriting services for which Goldman Sachs has recognized compensation. Goldman Sachs may also in the future provide financial advisory and/or underwriting services to Six Flags, Cedar Fair, CopperSteel, H Partners and/or their respective affiliates and/or as applicable, portfolio companies, for which Goldman Sachs Investment Banking may receive compensation. Affiliates of Goldman Sachs also may have co-invested with H Partners and its affiliates from time to time and may have invested in limited partnership units of affiliates of H Partners from time to time and may do so in the future.

The Six Flags Board selected Goldman Sachs as its financial advisor because it is an internationally recognized investment banking firm that has substantial experience in transactions similar to the transactions contemplated by the Merger Agreement. Pursuant to a letter agreement dated September 15, 2023, Six Flags engaged Goldman Sachs to act as its financial advisor in connection with the Mergers. The engagement letter between Six Flags and Goldman Sachs provides for a transaction fee that is estimated, based on the information available as of the date of announcement, at approximately $60.3 million, $5 million of which became payable at announcement of the Merger Agreement, and the remainder of which is contingent upon consummation of the Mergers. In addition, Six Flags has agreed to reimburse Goldman Sachs for certain of its expenses, including attorneys’ fees and disbursements, and to indemnify Goldman Sachs and related persons against various liabilities, including certain liabilities under the federal securities laws.

Certain Unaudited Prospective Financial Information

Neither Six Flags nor Cedar Fair, as a matter of course, makes public long-term forecasts or internal projections as to future performance, revenues, production, earnings or other results due to, among other reasons, the uncertainty of the underlying assumptions and estimates. In connection with the Mergers, the following unaudited prospective financial information was prepared: (i) certain unaudited prospective financial information with respect to Six Flags on a standalone basis for the fiscal years 2023 through 2028, prepared by Six Flags management, which we refer to as the “Six Flags Standalone Projections,” (ii) certain unaudited prospective financial information with respect to Cedar Fair on a standalone basis for the fiscal years 2023 through 2028, prepared by Cedar Fair management, which we refer to as the “Cedar Fair Standalone Projections,” (iii) certain estimates of synergies expected to be realized following the completion of the Mergers for fiscal years 2024 through 2028, jointly prepared by Six Flags management and Cedar Fair management, which we refer to as the “Synergy Projections,” and (iv) certain unaudited prospective financial information with respect to the combined company on a pro forma basis after giving effect to the Mergers for fiscal years 2024 through 2028 comprised of the Cedar Fair Standalone Projections, the Six Flags Standalone Projections and the Synergy Projections, which we refer to as the “Combined Company Projections.” We refer to the Six Flags Standalone Projections, the Cedar Fair Standalone Projections, the Synergy Projections and the Combined Company Projections as the “Forecasted

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Financial Information.” The Forecasted Financial Information was provided by Six Flags management to the Six Flags Board for the purposes of considering, analyzing and evaluating the Mergers and to Goldman Sachs, and the Six Flags Board directed Goldman Sachs to use the Forecasted Financial Information in connection with its financial analysis and opinion, as described in the section entitled “The Mergers—Opinion of Six Flags’ Financial Advisor.”

The Six Flags Standalone Projections and the Cedar Fair Standalone Projections were prepared treating Six Flags and Cedar Fair, as applicable, on a standalone basis, without giving effect to the Mergers, and exclude (i) any impact of the negotiation or execution of the Merger Agreement or the Mergers; (ii) the expenses that have already been and will be incurred in connection with completing the Mergers; (iii) the potential synergies that may be achieved by the combined company as a result of the Mergers; (iv) the effect of any business or strategic decision or action that has been or will be taken as a result of the Merger Agreement having been executed or in anticipation of completing the Mergers; or (v) the effect of any business or strategic decisions or actions which would likely have been taken if the Merger Agreement had not been executed but which were instead altered, accelerated, postponed or not taken in anticipation of the Mergers. Because the Six Flags Standalone Projections and the Cedar Fair Standalone Projections were developed for Six Flags and Cedar Fair, respectively, as independent companies without giving effect to the Mergers, the respective projections do not reflect any synergies that may be realized as a result of the Mergers or any changes to Six Flags’ or Cedar Fair’s respective operations or strategy that may be implemented after completion of the Mergers.

The Forecasted Financial Information is not included in this proxy statement/prospectus to influence any decision on whether to vote for the Merger Agreement Proposal, the Compensation Advisory Proposal or the Adjournment Proposal, but rather is included in this proxy statement/prospectus to give stockholders access to certain non-public information that was provided to the Six Flags Board and Six Flags’ financial advisor. The inclusion of the Forecasted Financial Information should not be regarded as an indication that the Six Flags Board, Six Flags, the Cedar Fair Board, Cedar Fair or their respective members of management or financial advisors or any other recipient of this information considered, or now considers, them to be necessarily predictive of actual future results, and they should not be relied on as such. There can be no assurance that the projected results will be realized or that actual results of Six Flags, Cedar Fair, or the post-Closing combined company will not be materially lower or higher than estimated, whether or not the Mergers are completed. The Forecasted Financial Information is based solely on information available to Six Flags management and Cedar Fair management, as applicable, at the time of their preparation and have not been updated or revised to reflect information or results after the date they were prepared or as of the date of this proxy statement/prospectus. Six Flags may in the future report results of operations for periods included in the Six Flags Standalone Projections that will be completed following the preparation of the Six Flags Standalone Projections. Cedar Fair may in the future report results of operations for periods included in the Cedar Fair Standalone Projections that will be completed following the preparation of the Cedar Fair Standalone Projections. Stockholders and investors are urged to refer to Six Flags’ and Cedar Fair’s periodic filings with the SEC for information on Six Flags’ and Cedar Fair’s actual historical results.

The Forecasted Financial Information was not prepared with a view toward public disclosure or with a view toward compliance with the published guidelines established by the American Institute of Certified Public Accountants for preparation or presentation of prospective financial information, but, in the view of Six Flags management, were reasonably prepared in good faith on a basis reflecting the best available estimates and judgments at the time of preparation, and presented as of the time of preparation, to the best of management’s knowledge and belief, the expected future financial performance of Six Flags and Cedar Fair, respectively, and, in the case of the Synergy Projections and the Combined Company Projections, the combined company. However, this information is not fact and should not be relied upon as being necessarily predictive of actual future results, and readers of this proxy statement/prospectus are cautioned not to place undue reliance on the Forecasted Financial Information. Although Six Flags management believe there is a reasonable basis for the Forecasted Financial Information, Six Flags and Cedar Fair caution that actual future results could be materially different from the Forecasted Financial Information. Neither Six Flags’ or Cedar Fair’s respective independent

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auditors, nor any other independent accountants, have compiled, examined or performed any procedures with respect to the prospective financial information contained herein, nor have they expressed any opinion or any other form of assurance on such information or its achievability, and assume no responsibility for, and disclaim any association with, the prospective financial information. Cedar Fair’s independent registered public accounting firm, Deloitte & Touche LLP, has not audited, reviewed, compiled or performed any procedures with respect to this preliminary financial information and, accordingly, Deloitte & Touche LLP does not express an opinion or any other form of assurance with respect thereto.

The Forecasted Financial Information is subject to estimates and assumptions in many respects and, as a result, subject to interpretation. While presented with numerical specificity, the Forecasted Financial Information is based upon a variety of estimates and assumptions that are inherently uncertain, though considered reasonable by Six Flags management as of the date of their preparation. These estimates and assumptions may prove to be impacted by any number of factors, including the impact of the announcement, pendency and consummation of the Mergers, general economic conditions, trends in the out-of-home entertainment industry, regulatory and financial market conditions and other risks and uncertainties described or incorporated by reference in the sections entitled “Risk Factors” and “Cautionary Statement Regarding Forward-Looking Statements” in this proxy statement/prospectus, all of which are difficult to predict and many of which are beyond the control of Six Flags and Cedar Fair and will be beyond the control of the combined company following the completion of the Mergers. Also see the section entitled “Where You Can Find More Information.” The Forecasted Financial Information also reflects assumptions as to certain business decisions that are subject to change. There can be no assurance that the Forecasted Financial Information will be realized, and actual results will likely differ, and may differ materially, from those shown. Generally, the further out the period to which the Forecasted Financial Information relate, the less predictive the information becomes.

The Forecasted Financial Information includes non-GAAP financial measures for each of Six Flags and Cedar Fair. Please see the tables below for a description of how Six Flags and Cedar Fair define these non-GAAP financial measures for purposes of the Forecasted Financial Information in this section. Non-GAAP financial measures should not be considered in isolation from, or as a substitute for, financial information presented in accordance with GAAP, and non-GAAP financial measures used by Six Flags and Cedar Fair may not be comparable to similarly titled measures used by other companies. The SEC rules that would otherwise require a reconciliation of an adjusted financial measure to a GAAP financial measure do not apply to adjusted financial measures provided to a board of directors or a financial advisor in connection with a proposed business combination such as the Mergers if the disclosure is included in a document such as this proxy statement/prospectus. In addition, reconciliations of adjusted financial measures were not relied upon by the Six Flags Board, the Cedar Fair Board or their respective members of management or financial advisors in connection with their respective evaluation of the Mergers. Accordingly, neither Six Flags nor Cedar Fair has provided a reconciliation of the adjusted financial measures included in the Forecasted Financial Information to the relevant GAAP financial measures.

None of Six Flags, Cedar Fair, CopperSteel, the combined company or their respective affiliates, officers, directors, advisors or other representatives can provide any assurance that actual results will not differ from the Forecasted Financial Information, and, except as required by applicable law, none of Six Flags, Cedar Fair, CopperSteel, the combined company or their respective affiliates, officers, directors, advisors or other representatives undertakes any obligation to update, or otherwise revise or reconcile, the Forecasted Financial Information to reflect circumstances existing after the date the Forecasted Financial Information was generated or to reflect the occurrence of future events even in the event that any or all of the assumptions underlying the Forecasted Financial Information are shown to be inappropriate. None of Six Flags, Cedar Fair, CopperSteel, the combined company or their respective affiliates, officers, directors, advisors or other representatives has made or makes any representation to any Six Flags Stockholder, Cedar Fair Unitholder or other person regarding Six Flags’ or Cedar Fair’s respective ultimate performance compared to the information contained in the Forecasted Financial Information or that forecasted results will be achieved. Six Flags has made no representation to Cedar Fair, in the Merger

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Agreement or otherwise, concerning the Six Flags Standalone Projections. Cedar Fair has made no representation to Six Flags, in the Merger Agreement or otherwise, concerning the Cedar Fair Standalone Projections.

Six Flags Standalone Projections

The following table presents a summary of the unaudited prospective financial information of Six Flags on a standalone basis prepared by Six Flags management for Six Flags’ fiscal years 2023 through 2028, which information is referred to as the “Six Flags Standalone Projections.”

Cedar Fair Forecasted Financial Information

Cedar Fair Standalone Projections

The following table presents a summary of the unaudited prospective financial information of Cedar Fair on a standalone basis prepared by Cedar Fair management for Cedar Fair’s fiscal years 2023 through 2028, which information is referred to as the “Cedar Fair Standalone Projections.”

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Certain Combined Company Unaudited Prospective Financial Information

Synergy Projections

The following table presents certain estimates of revenue and cost synergies expected to be realized by the combined company following the completion of the Mergers jointly prepared by Six Flags management and Cedar Fair management for the combined company’s fiscal years 2024 through 2028, which information is referred to as the “Synergy Projections.”

Combined Company Projections

The following table presents certain unaudited prospective financial information for fiscal years 2023 through 2028 for the combined company on a pro forma basis, jointly prepared by Six Flags management and Cedar Fair management for the combined company’s fiscal years 2023 through 2028, which information is referred to as the “Combined Company Projections.” The Combined Company Projections do not reflect the costs to achieve the synergies reflected in the projections.

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Recommendation of the Six Flags Board and Six Flags’ Reasons for the Mergers

On November 1, 2023, the Six Flags Board unanimously (i) determined that the Merger Agreement and the Six Flags Merger were advisable and fair to, and in the best interests of, Six Flags and the Six Flags Stockholders, (ii) approved (A) the form, terms and conditions of the Merger Agreement, (B) the execution, delivery and performance by Six Flags thereof and (C) subject to the adoption of the Merger Agreement at the Six Flags Special Meeting, the consummation of the transactions contemplated by the Merger Agreement, including the Six Flags Merger and the declaration of the Special Dividend, (iii) resolved to recommend that the Six Flags Stockholders adopt the Merger Agreement on the terms and subject to the conditions set forth in the Merger Agreement and (iv) directed that the adoption of the Merger Agreement be submitted to the Six Flags Stockholders at the Six Flags Special Meeting. The Six Flags Board unanimously recommends that Six Flags Stockholders (i) vote “FOR” the Merger Agreement Proposal; (ii) vote “FOR” the Compensation Advisory Proposal; and (iii) vote “FOR” the Adjournment Proposal.

In reaching its decision to approve and declare advisable the Merger Agreement and recommend its adoption, the Six Flags Board held a number of meetings and consulted with Six Flags management, outside legal counsel and its financial advisors, as further described in the section entitled “The Mergers — Background of the Mergers.” The Six Flags Board considered a number of factors when evaluating the Merger Agreement, many of which support the Six Flags Board’s determination that the Merger Agreement and the transactions contemplated by the Merger Agreement are advisable, fair to and in the best interests of Six Flags and the Six Flags Stockholders, and its recommendation that the holders of Six Flags Common Stock adopt the Merger Agreement. The Six Flags Board considered these factors as a whole and without assigning relative weights to each such factor, and overall considered the relevant factors to be favorable to, and in support of, its determinations and recommendations with respect to the Merger Agreement. The factors included (not necessarily presented in order of relative importance):

Strategic Considerations and Synergies

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Merger Consideration and the Special Dividend

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Opinion of Six Flags’ Financial Advisor

Terms of the Merger Agreement