CONSOL Energy (CEIX) 424B3Prospectus supplement

Filed Pursuant to Rule 424(b)(3)
Registration No. 333-282453

JOINT LETTER TO STOCKHOLDERS OF CONSOL ENERGY INC.

AND STOCKHOLDERS OF ARCH RESOURCES, INC.

Dear Stockholders:

On August 20, 2024, CONSOL Energy Inc. (“CONSOL”), Mountain Range Merger Sub Inc., a wholly owned subsidiary of CONSOL (“Merger Sub”), and Arch Resources, Inc. (“Arch”) entered into an Agreement and Plan of Merger (as it may be amended from time to time, the “merger agreement”), which provides for the combination of CONSOL and Arch in an all-stock merger of equals transaction. Upon the terms and subject to the conditions set forth in the merger agreement, Merger Sub will merge with and into Arch (the “merger”), with Arch continuing as the surviving corporation in the merger and a wholly owned subsidiary of CONSOL.

Holders of CONSOL common stock (as defined below) (the “CONSOL stockholders”) as of the close of business on November 26, 2024, the record date, are invited to virtually attend a special meeting of CONSOL stockholders (the “CONSOL special meeting”) on January 9, 2025, at 8:00 a.m. Eastern Time, via live webcast at www.virtualshareholdermeeting.com/CEIX2025SM (the “CONSOL special meeting website”). At the CONSOL special meeting, CONSOL stockholders will be asked to consider and vote upon: (1) a proposal to approve the issuance of shares of common stock, par value $0.01 per share, of CONSOL (“CONSOL common stock”) in connection with the merger (the “CONSOL issuance proposal”), (2) a proposal to adopt an amendment to CONSOL’s Amended and Restated Certificate of Incorporation (as amended prior to the date of this joint proxy statement/prospectus, the “CONSOL certificate of incorporation”), to increase the number of authorized shares of CONSOL common stock from 62,500,000 shares to 125,000,000 shares (the “CONSOL charter amendment proposal”) and (3) a proposal to approve one or more adjournments of the CONSOL special meeting to a later date or time, if necessary or appropriate, including adjournments to permit the solicitation of additional votes or proxies if there are not sufficient votes cast at the CONSOL special meeting to approve the CONSOL issuance proposal or the CONSOL charter amendment proposal (the “CONSOL adjournment proposal”).

Holders of Arch common stock (as defined below) (the “Arch stockholders”) as of the close of business on November 26, 2024, the record date, are invited to virtually attend a special meeting of Arch stockholders (the “Arch special meeting”) on January 9, 2025, at 8:00 a.m. Central Time, via live webcast at www.virtualshareholdermeeting.com/ARCH2025SM (the “Arch special meeting website”). At the Arch special meeting, Arch stockholders will be asked to consider and vote upon: (1) a proposal to adopt the merger agreement (the “Arch merger proposal”), (2) a non-binding advisory proposal to approve certain compensation that may be paid or become payable to Arch’s named executive officers that is based on or otherwise relates to the merger (the “Arch non-binding executive compensation advisory proposal”) and (3) a proposal to approve one or more adjournments of the Arch special meeting to a later date or time, if necessary or appropriate, including adjournments to permit the solicitation of additional votes or proxies if there are not sufficient votes cast at the Arch special meeting to approve the Arch merger proposal (the “Arch adjournment proposal”).

For Arch stockholders, if the merger is completed, you will be entitled to receive, for each issued and outstanding share of Class A common stock, par value $0.01 per share (“Arch Class A common stock”), and Class B common stock, par value $0.01 per share (“Arch Class B common stock” and together with Arch Class A common stock, “Arch common stock”), of Arch owned by you immediately prior to the effective time of the merger, 1.326 shares of CONSOL common stock (the “merger consideration”), as further described in the joint proxy statement/prospectus accompanying this notice. The market value of the merger consideration will fluctuate with the price of CONSOL common stock, and the difference between the market value of the merger consideration and the market value of Arch common stock will fluctuate with the market prices of CONSOL common stock and Arch Class A common stock. Based on the closing price of CONSOL common stock on August 20, 2024, the last trading day before the public announcement of the signing of the merger agreement, the value of the per share merger consideration payable to holders of Arch common stock upon completion of the merger was approximately $125.61, which is approximately $1.13 less than the closing price of Arch Class A common stock on August 20, 2024. Based on the closing price of CONSOL common stock on November 22, 2024, the last practicable date before the date of the joint proxy statement/prospectus accompanying this notice, the value of the per share merger consideration payable to holders of Arch common stock upon completion of the merger was approximately $174.67, which is approximately $1.03 more than the closing price of Arch Class A common stock on November 22, 2024. Arch stockholders should obtain current stock price quotations for CONSOL common stock and Arch Class A common stock. CONSOL common stock is

traded on the New York Stock Exchange under the symbol “CEIX,” and Arch Class A common stock is traded on the New York Stock Exchange under the symbol “ARCH.”

The CONSOL board of directors has unanimously determined that the merger agreement and the transactions contemplated by the merger agreement, including the issuance of shares of CONSOL common stock in connection with the merger and the amendment to the CONSOL certificate of incorporation to increase the number of authorized shares of CONSOL common stock from 62,500,000 shares to 125,000,000 shares, are fair to, and in the best interests of, CONSOL and its stockholders; has unanimously approved and declared advisable the merger agreement and the transactions contemplated by the merger agreement, including the issuance of shares of CONSOL common stock in connection with the merger and the amendment to the CONSOL certificate of incorporation to increase the number of authorized shares of CONSOL common stock from 62,500,000 shares to 125,000,000 shares; and unanimously recommends that CONSOL stockholders vote “FOR” the CONSOL issuance proposal, “FOR” the CONSOL charter amendment proposal and “FOR” the CONSOL adjournment proposal.

The Arch board of directors has unanimously determined that the merger agreement and the transactions contemplated by the merger agreement, including the merger, are fair to, and in the best interests of, Arch stockholders; has unanimously approved and declared advisable the merger agreement and the transactions contemplated by the merger agreement, including the merger; and unanimously recommends that Arch stockholders vote “FOR” the Arch merger proposal, “FOR” the Arch non-binding executive compensation advisory proposal and “FOR” the Arch adjournment proposal.

CONSOL and Arch will each hold a virtual special meeting of its stockholders to consider certain matters relating to the merger, which may be attended via the CONSOL special meeting website and the Arch special meeting website, respectively. CONSOL and Arch cannot complete the merger unless, among other things, CONSOL stockholders approve the CONSOL issuance proposal and the CONSOL charter amendment proposal and Arch stockholders approve the Arch merger proposal.

Your vote is very important. To ensure your representation at your company’s special meeting, complete and return the applicable enclosed proxy card or submit your proxy by phone or the Internet. Please vote promptly whether or not you expect to virtually attend your company’s special meeting. Submitting a proxy now will not prevent you from being able to vote at your company’s special meeting.

The joint proxy statement/prospectus accompanying this notice is also being delivered to Arch stockholders as CONSOL’s prospectus for its offering of shares of CONSOL common stock in connection with the merger.

The obligations of CONSOL and Arch to complete the merger are subject to the satisfaction or waiver of the conditions set forth in the merger agreement, a copy of which is included as part of the accompanying joint proxy statement/prospectus. The joint proxy statement/prospectus provides you with detailed information about the merger. It also contains or references information about CONSOL and Arch and certain related matters. You are encouraged to read the joint proxy statement/prospectus carefully and in its entirety. In particular, you should carefully read the section entitled “Risk Factors” beginning on page 39 of the joint proxy statement/prospectus for a discussion of risks you should consider in evaluating the merger and the issuance of shares of CONSOL common stock in connection with the merger and how they will affect you.

Sincerely,		Sincerely,
James A. Brock Chairman and Chief Executive Officer CONSOL Energy Inc.		Paul A. Lang Chief Executive Officer Arch Resources, Inc.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of the securities to be issued under the accompanying joint proxy statement/prospectus or passed upon the adequacy or accuracy of the disclosure in this document. Any representation to the contrary is a criminal offense.

The joint proxy statement/prospectus is dated November 26, 2024 and is first being mailed to stockholders of CONSOL and Arch on or about November 26, 2024.

275 Technology Drive, Suite 101

Canonsburg, Pennsylvania 15317

NOTICE OF THE SPECIAL MEETING OF STOCKHOLDERS OF

CONSOL ENERGY INC.

TO BE HELD VIRTUALLY VIA LIVE WEBCAST ON JANUARY 9, 2025

Dear Stockholder,

You are cordially invited to attend a virtual-only special meeting of stockholders (the “CONSOL special meeting”) of CONSOL Energy Inc. (“CONSOL”) to be held on January 9, 2025, at 8:00 a.m. Eastern Time, via live webcast at www.virtualshareholdermeeting.com/CEIX2025SM (the “CONSOL special meeting website”), for the following purposes:

The CONSOL special meeting will be held in a virtual meeting format only, via live webcast, and there will not be a physical meeting location. You will be able to attend the CONSOL special meeting online and vote your shares and submit questions electronically at the meeting by visiting the CONSOL special meeting website.

Stockholder approval of the CONSOL issuance proposal and the CONSOL charter amendment proposal is required to complete the transactions contemplated by the merger agreement, including the merger between Merger Sub and Arch (the “merger”). CONSOL stockholders will also be asked to approve the CONSOL adjournment proposal. CONSOL will transact no other business at the CONSOL special meeting. The record date for the CONSOL special meeting has been set as November 26, 2024. Only CONSOL stockholders of record as of the close of business on such record date are entitled to notice of, and to vote at, the CONSOL special meeting via the CONSOL special meeting website or any adjournment or postponement of the CONSOL special meeting. For additional information regarding the CONSOL special meeting, see the section entitled “Special Meeting of CONSOL Stockholders” beginning on page 57 of the joint proxy statement/prospectus accompanying this notice.

The CONSOL board unanimously recommends that CONSOL stockholders vote “FOR” the CONSOL issuance proposal, “FOR” the CONSOL charter amendment proposal and “FOR” the CONSOL adjournment proposal.

The accompanying joint proxy statement/prospectus describes the CONSOL proposals in more detail. Please refer to the attached document, 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 CONSOL special meeting. You are encouraged to read the entire document carefully before voting. A summary of the

merger agreement is included in the accompanying joint proxy statement/prospectus in the section entitled “The Merger Agreement” and a copy of the merger agreement is attached as Annex A to the accompanying joint proxy statement/prospectus, each of which are incorporated by reference into this notice to the same extent as if fully set forth herein. In addition, see the section entitled “Risk Factors” beginning on page 39 of the joint proxy statement/prospectus accompanying this notice for an explanation of the risks associated with the merger and the other transactions contemplated by the merger agreement.

PLEASE VOTE AS PROMPTLY AS POSSIBLE, WHETHER OR NOT YOU PLAN TO ATTEND THE CONSOL SPECIAL MEETING VIA THE CONSOL SPECIAL MEETING WEBSITE. IF YOU LATER DESIRE TO REVOKE OR CHANGE YOUR PROXY FOR ANY REASON, YOU MAY DO SO IN THE MANNER DESCRIBED IN THE ACCOMPANYING JOINT PROXY STATEMENT/PROSPECTUS. FOR FURTHER INFORMATION CONCERNING THE PROPOSALS BEING VOTED UPON, USE OF THE PROXY AND OTHER RELATED MATTERS, YOU ARE URGED TO READ THE ACCOMPANYING JOINT PROXY STATEMENT/PROSPECTUS.

If you have any questions concerning the CONSOL proposals, the merger or the accompanying joint proxy statement/prospectus, would like additional copies or need help voting your shares of CONSOL common stock, please contact CONSOL’s proxy solicitor:

MacKenzie Partners, Inc.

1407 Broadway, 27th Floor, New York, NY 10018

Banks and Brokers Call Collect: (212) 929-5500

All Others Call Toll-Free: (800) 322-2885

BY ORDER OF THE BOARD OF DIRECTORS,

Matthew S. Tyree

Interim General Counsel and Corporate Secretary

CONSOL Energy Inc.

One CityPlace Drive, Suite 300

St. Louis, Missouri 63141

NOTICE OF THE SPECIAL MEETING OF STOCKHOLDERS OF

ARCH RESOURCES, INC.

TO BE HELD VIRTUALLY VIA LIVE WEBCAST ON JANUARY 9, 2025

Dear Stockholder,

You are cordially invited to attend a virtual-only special meeting of stockholders (the “Arch special meeting”) of Arch Resources, Inc. (“Arch”) to be held on January 9, 2025, at 8:00 a.m. Central Time, via live webcast at www.virtualshareholdermeeting.com/ARCH2025SM (the “Arch special meeting website”), for the following purposes:

The Arch special meeting will be held in a virtual meeting format only, via live webcast, and there will not be a physical meeting location. You will be able to attend the Arch special meeting online and vote your shares and submit questions electronically at the meeting by visiting the Arch special meeting website.

Stockholder approval of the Arch merger proposal is required to complete the merger between Merger Sub and Arch, as contemplated by the merger agreement. Arch stockholders will also be asked to approve the Arch non-binding executive compensation advisory proposal and the Arch adjournment proposal. Arch will transact no other business at the Arch special meeting. The record date for the Arch special meeting has been set as November 26, 2024. Only Arch stockholders of record as of the close of business on such record date are entitled to notice of, and to vote at, the Arch special meeting via the Arch special meeting website or any adjournment or postponement of the Arch special meeting. For additional information regarding the Arch special meeting, see the section entitled “Special Meeting of Arch Stockholders” beginning on page 66 of the joint proxy statement/prospectus accompanying this notice.

The Arch board unanimously recommends that Arch stockholders vote “FOR” the Arch merger proposal, “FOR” the Arch non-binding executive compensation advisory proposal, and “FOR” the Arch adjournment proposal.

The accompanying joint proxy statement/prospectus describes the Arch proposals in more detail. Please refer to the attached document, 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 Arch special meeting. You are encouraged to read the entire document carefully before voting. A summary of the merger agreement is included in the accompanying joint proxy statement/prospectus in the section entitled “The Merger Agreement”

and a copy of the merger agreement is attached as Annex A to the accompanying joint proxy statement/prospectus, each of which are incorporated by reference into this notice to the same extent as if fully set forth herein. In addition, see the section entitled “Risk Factors” beginning on page 39 of the joint proxy statement/prospectus accompanying this notice for an explanation of the risks associated with the merger and the other transactions contemplated by the merger agreement.

PLEASE VOTE AS PROMPTLY AS POSSIBLE, WHETHER OR NOT YOU PLAN TO ATTEND THE ARCH SPECIAL MEETING VIA THE ARCH SPECIAL MEETING WEBSITE. IF YOU LATER DESIRE TO REVOKE OR CHANGE YOUR PROXY FOR ANY REASON, YOU MAY DO SO IN THE MANNER DESCRIBED IN THE ACCOMPANYING JOINT PROXY STATEMENT/PROSPECTUS. FOR FURTHER INFORMATION CONCERNING THE PROPOSALS BEING VOTED UPON, USE OF THE PROXY AND OTHER RELATED MATTERS, YOU ARE URGED TO READ THE ACCOMPANYING JOINT PROXY STATEMENT/PROSPECTUS.

If you have any questions concerning the Arch proposals, the merger or the accompanying joint proxy statement/prospectus, would like additional copies or need help voting your shares of Arch common stock, please contact Arch’s proxy solicitors:

Innisfree M&A Incorporated

501 Madison Avenue, 20th Floor, New York, NY 10022

Banks and Brokers Call Collect: (212) 750-5833

All Others Call Toll-Free: (877) 717-3905

or

D.F. King & Co., Inc.

48 Wall Street, 22nd Floor, New York, NY 10005

Banks and Brokers Call Collect: (212) 269-5550

All Others Call Toll-Free: (800) 848-3410

BY ORDER OF THE BOARD OF DIRECTORS,

Rosemary L. Klein

Senior Vice President—Law, General Counsel and Secretary

Arch Resources, Inc.

REFERENCES TO ADDITIONAL INFORMATION

This joint proxy statement/prospectus incorporates by reference important business and financial information about CONSOL Energy Inc. (“CONSOL”) and Arch Resources, Inc. (“Arch”) from other documents that are not included in or delivered with this joint proxy statement/prospectus, including documents that CONSOL and Arch have filed with the U.S. Securities and Exchange Commission (“SEC”). For a listing of documents incorporated by reference herein, see the section entitled “Where You Can Find More Information.” This information is available for you to review free of charge at the public reference room of the SEC located at 100 F Street, N.E., Washington, DC 20549, and through the SEC’s website at www.sec.gov.

You may request copies of this joint proxy statement/prospectus and any of the documents incorporated by reference herein or other information concerning CONSOL or Arch, without charge, upon written or oral request to the applicable company’s principal executive offices. The respective addresses and phone numbers of such principal executive offices are listed below.

To obtain timely delivery of these documents before the CONSOL special meeting (as defined in the section entitled “Questions and Answers about the Merger and the Special Meetings”), CONSOL stockholders must request the information no later than January 2, 2025 (which is five business days before the date of the CONSOL special meeting).

To obtain timely delivery of these documents before the Arch special meeting (as defined in the section entitled “Questions and Answers about the Merger and the Special Meetings”), Arch stockholders must request the information no later than January 2, 2025 (which is five business days before the date of the Arch special meeting).

In addition, if you have questions about the merger or this joint proxy statement/prospectus, would like additional copies of this joint proxy statement/prospectus or need to obtain proxy cards or other information related to the proxy solicitation, contact MacKenzie Partners, Inc., the proxy solicitor for CONSOL, toll-free at (800) 322-2885, or for banks and brokers, collect at (212) 929-5500, or Innisfree M&A Incorporated or D.F. King & Co., Inc., the proxy solicitors for Arch, toll-free at (877) 717-3905, or for brokers and banks, collect at (212) 750-5833, or toll-free at (800) 848-3410, or for brokers or banks, collect at (212) 269-5550, respectively. You will not be charged for any of these documents that you request.

ABOUT THIS JOINT PROXY STATEMENT/PROSPECTUS

This document, which forms part of a registration statement on Form S-4 filed with the SEC by CONSOL (File No. 333-282453), constitutes a prospectus of CONSOL under Section 5 of the Securities Act of 1933, as amended (the “Securities Act”), with respect to the shares of common stock of CONSOL, par value $0.01 per share (“CONSOL common stock”), to be issued to Arch stockholders pursuant to the Agreement and Plan of Merger, dated as of August 20, 2024 (as it may be amended from time to time, the “merger agreement”), among CONSOL, Mountain Range Merger Sub Inc. (“Merger Sub”) and Arch.

This document also constitutes a notice of meeting and proxy statement of each of CONSOL and Arch under Section 14(a) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”).

CONSOL has supplied all information contained or incorporated by reference herein relating to CONSOL, and Arch has supplied all information contained or incorporated by reference herein relating to Arch. CONSOL and Arch have both contributed to the information relating to the merger agreement contained in this joint proxy statement/prospectus.

Neither CONSOL nor Arch has authorized anyone to provide any information or to make any representations other than those contained in or incorporated by reference in this joint proxy statement/prospectus in connection with any vote, the giving or withholding of any proxy or any investment decision in connection with the merger agreement. CONSOL and Arch take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. This joint proxy statement/prospectus is dated November 26, 2024, and you should not assume that the information contained in this joint proxy statement/prospectus is accurate as of any date other than such date unless otherwise specifically provided herein. Further, you should not assume that the information incorporated by reference in this joint proxy statement/prospectus is accurate as of any date other than the date of the incorporated document. Neither the mailing of this joint proxy statement/prospectus to CONSOL or Arch stockholders nor the issuance by CONSOL of shares of CONSOL common stock pursuant to the merger agreement will create any implication to the contrary.

All currency amounts referenced in this joint proxy statement/prospectus are in U.S. dollars unless otherwise indicated.

TABLE OF CONTENTS

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QUESTIONS AND ANSWERS ABOUT THE MERGER AND THE SPECIAL MEETINGS

The following are some questions that you, as a CONSOL stockholder or an Arch stockholder, as applicable, may have regarding the merger, the issuance of shares of CONSOL common stock to Arch stockholders in connection with the merger, the proposed amendment to CONSOL’s charter and the other matters being considered at the CONSOL special meeting and the Arch special meeting, and the answers to those questions. CONSOL and Arch urge you to carefully read the remainder of this joint proxy statement/prospectus because the information in this section does not provide all the information that might be important to you with respect to the merger, the issuance of shares of CONSOL common stock in connection with the merger, the proposed amendment to CONSOL’s charter and the other matters being considered at the CONSOL special meeting and the Arch special meeting. Additional important information is also contained in the annexes to, and the documents incorporated by reference in, this document.

CONSOL Stockholders. In order to consummate the merger, holders of CONSOL common stock (the “CONSOL stockholders”) must (i) approve the issuance of shares of CONSOL common stock pursuant to the terms of the merger agreement (the “CONSOL issuance proposal”) and (ii) adopt an amendment to CONSOL’s Amended and Restated Certificate of Incorporation (as amended prior to the date of this joint proxy statement/prospectus, the “CONSOL certificate of incorporation”), in the form attached to this joint proxy statement/prospectus as Annex D (the “CONSOL charter amendment”), to increase the number of authorized shares of CONSOL common stock from 62,500,000 shares to 125,000,000 shares (the “CONSOL charter amendment proposal”), in each case in accordance with the rules of the New York Stock Exchange (the “NYSE”) and CONSOL’s organizational documents. CONSOL is holding a virtual special meeting of its stockholders (the “CONSOL special meeting”) to obtain those approvals. CONSOL stockholders will also be asked to vote on a proposal to approve one or more adjournments of the CONSOL special meeting to a later date or time, if necessary or appropriate, including adjournments to permit the solicitation of additional votes or proxies if there are not sufficient votes cast at the CONSOL special meeting to approve the CONSOL issuance proposal or the CONSOL charter amendment proposal (the “CONSOL adjournment proposal” and, together with the CONSOL issuance proposal and the CONSOL charter amendment proposal, the “CONSOL proposals”). Your vote is very important. We encourage you to submit a proxy to have your shares of CONSOL common stock voted as soon as possible.

Arch Stockholders. In order to consummate the merger, holders of Arch common stock (the “Arch stockholders”) must adopt the merger agreement (the “Arch merger proposal”) in accordance with the General Corporation Law of the State of Delaware (as it may be amended, the “DGCL”). Arch is holding a virtual special meeting of its stockholders (the “Arch special meeting”) to obtain this approval. Arch stockholders will also be asked to vote on (i) a non-binding advisory proposal to approve certain compensation that may be paid or become payable to Arch’s named executive officers that is based on or otherwise relates to the merger (the “Arch non-binding executive compensation advisory proposal”) and (ii) a proposal to approve one or more adjournments of the Arch special meeting to a later date or time, if necessary or appropriate, including adjournments to permit the solicitation of additional votes or proxies if there are not sufficient votes cast at the Arch special meeting to approve the Arch merger proposal (the “Arch adjournment proposal” and, together with the Arch merger proposal and the Arch non-binding executive compensation advisory proposal, the “Arch proposals”). Your vote is very important. We encourage you to submit a proxy to have your shares of Arch common stock voted as soon as possible.

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Arch. The Arch special meeting will be held virtually via live webcast on January 9, 2025, at 8:00 a.m. Central Time. Arch stockholders will be able to attend the Arch special meeting online and vote their shares and submit questions electronically during the meeting by visiting www.virtualshareholdermeeting.com/ARCH2025SM (the “Arch special meeting website”). Because the Arch special meeting is completely virtual and being conducted via live webcast, Arch stockholders will not be able to attend the meeting in person.

Arch. The Arch stockholders are being asked to consider and vote on:

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Arch. Your vote is very important. The merger cannot be completed unless the Arch merger proposal is approved by the affirmative vote of a majority of the outstanding shares of Arch common stock entitled to vote on such proposal. Only Arch stockholders as of the close of business on the record date are entitled to vote at the Arch special meeting. The board of directors of Arch (the “Arch board”) unanimously recommends that such Arch stockholders vote “FOR” the Arch merger proposal, “FOR” the Arch non-binding executive compensation advisory proposal and “FOR” the Arch adjournment proposal.

The CONSOL charter amendment proposal. Approval of the CONSOL charter amendment proposal requires the affirmative vote of a majority of the outstanding shares of CONSOL common stock entitled to vote on such proposal. Abstentions, broker non-votes, or any failure by a CONSOL stockholder to vote (e.g., by not submitting a proxy and not voting at the CONSOL special meeting) will have the same effect as a vote “AGAINST” the CONSOL charter amendment proposal.

The CONSOL adjournment proposal. Approval of the CONSOL adjournment proposal requires the affirmative vote of a majority of the shares of CONSOL common stock present via the CONSOL special meeting website or by proxy at the CONSOL special meeting and entitled to vote on such proposal, whether or not a quorum is present. Abstentions will have the same effect as a vote “AGAINST” the CONSOL adjournment proposal, while broker non-votes or any failure by a CONSOL stockholder to vote (e.g., by not submitting a proxy and not voting at the CONSOL special meeting) will have no effect on the outcome of the CONSOL adjournment proposal. Approval of this proposal is not a condition to the completion of the merger.

The Arch non-binding executive compensation advisory proposal. Approval of the Arch non-binding executive compensation advisory proposal requires the affirmative vote of a majority of the shares of Arch common stock voting thereon at the Arch special meeting. Abstentions, broker non-votes, or any failure by an Arch stockholder to vote (e.g., by not submitting a proxy and not voting at the Arch special meeting) will have no effect on the outcome of the Arch non-binding executive compensation advisory proposal. As an advisory vote, this proposal is not binding on Arch or the Arch board or CONSOL or the CONSOL board, and approval of this proposal is not a condition to the completion of the merger.

The Arch adjournment proposal. Approval of the Arch adjournment proposal requires the affirmative vote of a majority of the shares of Arch common stock present via the Arch special meeting website or by proxy at the Arch special meeting, whether or not a quorum is present. Abstentions and broker non-votes will have the same effect as a vote “AGAINST” the Arch adjournment proposal, while any failure by an Arch stockholder to vote (e.g., by not submitting a proxy and not voting at the Arch special meeting) will have no effect on the outcome of the Arch adjournment proposal. Approval of this proposal is not a condition to the completion of the merger.

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CONSOL Proposals

Under the current NYSE rules, brokers, banks or other nominees do not have discretionary authority to vote on any of the CONSOL proposals at the CONSOL special meeting. Because all of the proposals for consideration at the CONSOL special meeting are “non-routine,” it is not expected that there will be any broker non-votes at the CONSOL special meeting. However, if there are any broker non-votes, they will have (1) the same effect as a vote “AGAINST” the CONSOL charter amendment proposal and (2) no effect on the outcome of the CONSOL issuance proposal or the CONSOL adjournment proposal.

Arch Proposals

Under the current NYSE rules, brokers, banks or other nominees do not have discretionary authority to vote on any of the Arch proposals at the Arch special meeting. Because all of the proposals for consideration at the Arch special meeting are “non-routine,” it is not expected that there will be any broker non-votes at the Arch special meeting. However, if there are any broker non-votes, they will have (1) the same effect as a vote “AGAINST” the Arch merger proposal and the Arch adjournment proposal and (2) no effect on the outcome of the Arch non-binding executive compensation advisory proposal.

Arch. Help and technical support for accessing and participating in the virtual meeting will be available by following the instructions on the virtual meeting website (www.virtualshareholdermeeting.com/ARCH2025SM). If you encounter any difficulties accessing the Arch special meeting during the check-in or meeting time, please call the technical support number that will be posted on the virtual meeting website login page (www.virtualshareholdermeeting.com/ARCH2025SM). Please give yourself sufficient time to log in and ensure you can hear the streaming audio before the meeting starts.

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If you receive the merger consideration and would otherwise be entitled to receive a fractional share of CONSOL common stock, you will receive cash in lieu of such fractional share, and you will not be entitled to dividends, voting rights or any other rights in respect of such fractional share. For additional information regarding the merger consideration, see the sections entitled “The Merger—Consideration to Arch Stockholders” and “The Merger Agreement—Effect of the Merger on Capital Stock; Merger Consideration.”

Effective as of the effective time of the merger (i) except as otherwise provided in the merger agreement, each restricted stock unit award of Arch (an “Arch RSU award”) that is outstanding immediately prior to the effective time of the merger (and any related cash dividend equivalents) will, by virtue of the merger and without any action on the part of the holder thereof, fully vest, be cancelled and automatically converted into the right to receive, within five business days following the effective time of the merger, (A) a number of newly issued shares of CONSOL common stock equal to the product (rounded to the nearest whole number) of (x) the number of shares of Arch common stock subject to such Arch RSU award as of immediately prior to the effective time of the merger (whether vested or unvested), multiplied by (y) the exchange ratio; provided that CONSOL will withhold the number of shares of CONSOL common stock as reasonably determined by CONSOL to satisfy any tax withholding obligations associated with the settlement of such Arch RSU award (with any fractional shares of CONSOL common stock treated in accordance with the merger agreement), and (B) payment in cash of any accrued and unpaid dividend equivalents related to such Arch RSU award (as determined immediately prior to the effective time of the merger), less applicable withholdings, and (ii) each Arch RSU award that is granted after August 20, 2024 and outstanding and unvested immediately prior to the effective time of the merger will, by virtue of the merger and without any action on the part of the holder thereof, be converted into a restricted stock unit award corresponding to a number of shares of CONSOL common stock (a “CONSOL RSU award”) (rounded to the nearest whole number of shares) equal to the product of (x) the number of shares of Arch common stock subject to such Arch RSU award as of immediately prior to the effective time of the merger (whether vested of unvested), multiplied by (y) the exchange ratio. Each CONSOL RSU award will have the same terms and conditions as the corresponding Arch RSU award had immediately prior to the effective time of the merger.

Arch PSU Awards

Effective as of the effective time of the merger (i) except as otherwise provided in the merger agreement, each performance-based restricted stock unit award of Arch (an “Arch PSU award”) that is outstanding immediately prior to the effective time of the merger (and any related cash dividend equivalents) will, by virtue of the merger and without any action on the part of the holder thereof, be converted into the right to receive, within five business days following the effective time of the merger, (A) a number of newly issued shares of CONSOL common stock equal to the product (rounded to the nearest whole number) of (I) the number of shares of Arch common stock subject to such Arch PSU award as of immediately prior to the effective time of the merger equal to the greater of (x) 100% of the target number of shares of Arch common stock subject to the Arch PSU award and (y) the number of shares of Arch common stock subject to the portion of the Arch PSU award that would have vested as of the effective time of the merger based on actual

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achievement of the performance goals related to such Arch PSU award as of the effective time of the merger (the “Vested PSU Award”), multiplied by (II) the exchange ratio; provided, that CONSOL will withhold the number of shares of CONSOL common stock as reasonably determined by CONSOL to satisfy any tax withholding obligations associated with the settlement of such Arch PSU award (with any fractional shares of CONSOL common stock treated in accordance with the merger agreement), and (B) payment in cash of any dividend equivalents related to the Vested PSU Award (as determined immediately prior to the effective time of the merger), less applicable withholdings, and (ii) each Arch PSU award that is granted after August 20, 2024 and is outstanding as of immediately prior to the effective time of the merger will, by virtue of the merger and without any action on the part of the holder thereof, be converted into a CONSOL RSU award (rounded to the nearest whole number of shares) equal to the product obtained by multiplying (x) the target number of shares of Arch common stock subject to such Arch PSU award by (y) the exchange ratio. Each CONSOL RSU award will have the same terms and conditions as the corresponding Arch PSU award had immediately prior to the effective time of the merger except that vesting of the award will be subject only to continuous service, and any performance-based objectives will cease to apply.

Assumption of Arch Equity Plan

At the effective time of the merger, CONSOL will assume Arch’s 2016 Omnibus Incentive Plan (the “Arch Equity Plan”) with the number of shares reserved and remaining for issuance under such Arch Equity Plan adjusted to a number of shares of CONSOL common stock determined by multiplying the number of shares of Arch common stock reserved and remaining for issuance under such Arch Equity Plan immediately prior to the effective time of the merger by the exchange ratio, rounded down to the nearest whole share.

For additional information regarding the treatment of Arch equity awards, see the section entitled “The Merger Agreement—Treatment of Arch Equity Awards in the Merger.”

At the effective time of the merger, each outstanding CONSOL RSU award granted prior to August 20, 2024 (and not previously forfeited in accordance with its terms) will vest and will be settled in the number of shares of CONSOL common stock covered by such award.

CONSOL RSU Awards Granted on or After August 20, 2024

Each outstanding CONSOL RSU award granted on or after August 20, 2024 will remain outstanding following the effective time and will have the same terms and conditions as in effect immediately prior to the effective time, including, in the case of executive officers of CONSOL, accelerated vesting of any such awards upon a qualifying termination.

CONSOL PSU Awards Granted Prior to August 20, 2024

At the effective time of the merger, each outstanding CONSOL PSU award granted prior to August 20, 2024 (and not previously forfeited in accordance with its terms) will be cancelled and converted into the right to receive a number of shares of CONSOL common stock equal to the number of shares of CONSOL common stock covered by such CONSOL PSU award (or cash equal to the market value of such shares, if applicable, under the award agreement terms) based on the greater of actual performance and target performance.

CONSOL PSU Awards Granted on or After August 20, 2024

Each outstanding CONSOL PSU award granted on or after August 20, 2024 will remain outstanding following the effective time and will have the same terms and conditions as in effect immediately prior to

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the effective time, including, in the case of executive officers of CONSOL, accelerated vesting of any such awards upon a qualifying termination.

For additional information regarding the treatment of CONSOL equity awards, see the section entitled “The Merger Agreement—Treatment of CONSOL Equity Awards in the Merger.”

Arch. The Arch board unanimously recommends that Arch stockholders vote “FOR” the Arch merger proposal, “FOR” the Arch non-binding executive compensation advisory proposal and “FOR” the Arch adjournment proposal. For additional information regarding how the Arch board recommends that Arch stockholders vote, see the section entitled “The Merger—Recommendation of the Arch Board of Directors and Reasons for the Merger.”

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Arch special meeting. The Arch board has fixed November 26, 2024 as the record date for the Arch special meeting. All holders of record of shares of Arch common stock as of the close of business on the record date are entitled to receive notice of, and to vote at, the Arch special meeting via the Arch special meeting website or by proxy, provided that those shares remain outstanding on the date of the Arch special meeting. As of the record date, there are expected to be approximately 18,108,352 shares of Arch Class A common stock outstanding and 257 shares of Arch Class B common stock outstanding. Attendance at the Arch special meeting via the Arch special meeting website is not required to vote. Instructions on how to vote your shares without virtually attending the Arch special meeting are provided in this section below.

Arch stockholders. Each Arch stockholder of record is entitled to one vote for each share of Arch common stock held of record by such stockholder as of the close of business on the record date.

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Quorum for Arch special meeting. The holders of a majority of the outstanding shares of Arch common stock entitled to vote at the Arch special meeting, present via the Arch special meeting website or by proxy, shall constitute a quorum for the transaction of business. If you submit a properly executed proxy card, even if you vote “against” the Arch proposals or “abstain” from voting on the Arch proposals, your shares of Arch common stock will be counted for purposes of calculating whether a quorum is present. Because all of the proposals for consideration at the Arch special meeting are “non-routine” under applicable NYSE rules, brokers, banks and other nominees do not have discretionary authority to vote on any of the Arch proposals and will not be able to vote on any of the Arch proposals absent instructions from the beneficial owner. Accordingly, it is not expected that there will be any broker non-votes at the Arch special meeting. Broker non-votes, if any, will not be considered present and entitled to vote on any of the Arch proposals for the purpose of determining the presence of a quorum with respect to the vote thereon.

If the merger is completed, shares of CONSOL common stock will continue to trade on the NYSE following the merger. However, if the merger is completed, CONSOL will be renamed “Core Natural Resources, Inc.” and its shares of common stock will trade on the NYSE under the ticker symbol “CNR.” The combined company will retain CONSOL’s current headquarters in Canonsburg, Pennsylvania. CONSOL and Arch have also agreed to certain governance matters relating to the board of directors and management of the combined company following the completion of the merger. See “Summary—Board of Directors and Management of the Combined Company Following the Completion of the Merger” and “The Merger Agreement—Organizational Documents; Directors and Officers” for more information.

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Arch. Shares of Arch common stock held directly in your name as the stockholder of record as of the close of business on November 26, 2024, the record date, may be voted at the Arch special meeting via the Arch special meeting website. Please note that attendance alone at the Arch special meeting via the Arch special meeting website will not cause the voting of your shares; you must affirmatively vote by proxy or via the Arch special meeting website. If you choose to attend the Arch special meeting and vote your shares via the

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Arch special meeting website, you will need the 16-digit control number included on your proxy card. If you are a beneficial owner of Arch common stock but not the stockholder of record of such shares of Arch common stock, you will need to obtain a control number from your broker, bank or other nominee holder of record giving you the right to vote the shares.

Arch. If you are a stockholder of record of Arch common stock as of the close of business on November 26, 2024, the record date, you can vote by proxy, phone, the Internet or mail by following the instructions provided in the enclosed proxy card. Please note that if you are a beneficial owner, you may vote by submitting voting instructions to your broker, bank or other nominee, or otherwise by following instructions provided by your broker, bank or other nominee. Phone and Internet voting may be available to beneficial owners. Please refer to the voting instruction form provided by your broker, bank or other nominee.

Arch. If your shares of Arch common stock are registered directly in your name with Arch’s transfer agent, Equiniti Trust Company, you are considered the stockholder of record with respect to those shares, and access to proxy materials is being provided directly to you. If your shares are held in a stock brokerage account or by a broker, bank or other nominee, then you are considered the beneficial owner of those shares, which are considered to be held in “street name.” Access to proxy materials is being provided to you by your broker, bank or other nominee who is considered the stockholder of record with respect to those shares.

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Direct holders (stockholders of record). For shares of CONSOL and/or Arch common stock held directly, complete, sign, date and return each proxy card (or cast your vote by phone or the Internet as provided on each proxy card) or otherwise follow the voting instructions provided in this joint proxy statement/prospectus in order to ensure that all of your shares of CONSOL and/or Arch common stock are voted.

Shares in “street name.” For shares of CONSOL and/or Arch common stock held in “street name” through a broker, bank or other nominee, follow the instructions provided by your broker, bank or other nominee to vote your shares.

Arch. If you sign, date and return your proxy and do not indicate how you want your shares of Arch common stock to be voted, then your shares of Arch common stock will be voted “FOR” the Arch merger proposal, “FOR” the Arch non-binding executive compensation advisory proposal and “FOR” the Arch adjournment proposal.

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If you are a beneficial owner of CONSOL common stock as of the close of business on the record date, you must follow the instructions of your broker, bank or other nominee to revoke or change your voting instructions.

Arch. Yes. If you are a stockholder of record of Arch common stock as of the close of business on the record date, whether you vote by phone, the Internet or mail, you can change or revoke your proxy before it is voted at the Arch special meeting in one of the following ways:

If you are a beneficial owner of Arch common stock as of the close of business on the record date, you must follow the instructions of your broker, bank or other nominee to revoke or change your voting instructions.

Arch stockholders. Arch stockholders may vote against the Arch merger proposal if they do not support the merger. Because shares of Arch Class A common stock are listed on the NYSE and Arch stockholders are not required to receive consideration other than shares of CONSOL common stock, which are listed on the NYSE, and cash in lieu of fractional shares in the merger, holders of Arch Class A common stock are not entitled to exercise appraisal rights under Delaware law in connection with the merger. Because shares of Arch Class B common stock are not listed on a nationally recognized exchange, holders of the 257 shares of Arch Class B common stock currently issued and outstanding are entitled to appraisal rights under Section 262 of the DGCL, provided that they have not waived such rights and comply with the conditions established by Section 262 of the DGCL. Additional information about the process to exercise appraisal rights will be provided to holders of Arch Class B common stock.

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Arch stockholders. The record date for Arch stockholders entitled to vote at the Arch special meeting is earlier than the date of the Arch special meeting. If you transfer your shares of Arch common stock after the record date but before the Arch special meeting, you will, unless special arrangements are made, retain your right to vote at the Arch special meeting but will have transferred the right to receive the merger consideration to the person to whom you transferred your shares of Arch common stock.

If the merger qualifies as a reorganization, then U.S. holders (as defined in the section entitled “Material U.S. Federal Income Tax Consequences of the Merger” beginning on page 188) of shares of Arch common stock generally will not recognize any gain or loss for U.S. federal income tax purposes upon receipt of CONSOL common stock in exchange for Arch common stock in the merger (other than gain or loss, if any, with respect to any cash received in lieu of a fractional share of CONSOL common stock). The material U.S. federal income tax consequences of the merger are discussed in more detail in the section entitled “Material U.S. Federal Income Tax Consequences of the Merger” beginning on page 188. The discussion of the material U.S. federal income tax consequences contained in this joint proxy statement/prospectus is intended to provide only a general discussion and is not a complete analysis or description of all potential U.S. federal income tax consequences of the merger that may vary with, or are dependent on, individual circumstances. In addition, it does not address the effects of any foreign, state or local tax laws or any U.S. federal tax laws other than U.S. federal income tax laws.

TAX MATTERS ARE COMPLICATED AND THE TAX CONSEQUENCES OF THE MERGER WILL DEPEND ON THE FACTS OF YOUR OWN SITUATION. YOU SHOULD CONSULT YOUR OWN TAX ADVISOR AS TO THE SPECIFIC TAX CONSEQUENCES OF THE MERGER TO YOU IN YOUR PARTICULAR CIRCUMSTANCES.

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If you are a holder of book-entry shares representing eligible shares of Arch common stock (“Arch book-entry shares”) that 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 merger

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consideration, cash in lieu of any fractional shares of CONSOL common stock and any dividends and other distributions on the shares of CONSOL common stock issuable as merger consideration, in each case, that DTC has the right to receive pursuant to the merger agreement.

If you are a holder of record of Arch book-entry shares that are not held through DTC, the exchange agent will deliver to you, as soon as reasonably practicable after the effective time of the merger, (1) a notice advising you of the effectiveness of the merger, (2) a statement reflecting the aggregate whole number of shares of CONSOL common stock (which will be in uncertificated book-entry form) that you have a right to receive pursuant to the merger agreement and (3) a check in the amount equal to the cash payable in lieu of any fractional shares of CONSOL common stock and dividends and other distributions on the shares of CONSOL common stock issuable to you as merger consideration.

No interest will be paid or accrued on any amount payable for shares of Arch common stock eligible to receive the merger consideration pursuant to the merger agreement.

For additional information on the exchange of Arch common stock for the merger consideration, see the section entitled “The Merger Agreement—Payment for Securities; Exchange.”

Arch. Arch has retained Innisfree M&A Incorporated (“Innisfree”) and D.F. King & Co., Inc. (“King”) to assist in the solicitation process. Arch has paid Innisfree a fee of $17,500 and will pay Innisfree a fee of $17,500, which may be supplemented by additional appropriate fees for certain additional services, as well as reasonable and customary documented expenses. Arch has paid King a fee of $12,500 and will pay King a fee of $12,500, which may be supplemented by additional reasonable and documented fees for additional services at King’s reasonable and customary rates as mutually agreed to in writing, as well as reasonable and customary documented expenses. Arch also has agreed to indemnify each of Innisfree and King against various liabilities and expenses that relate to or arise out of its solicitation of proxies (subject to certain exceptions).

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Arch has also elected to institute householding.

MacKenzie Partners, Inc.

1407 Broadway, 27th Floor, New York, NY 10018

Banks and Brokers Call Collect: (212) 929-5500

All Others Call Toll-Free: (800) 322-2885

Arch stockholders. If you have questions about the Arch special meeting or the information contained in this joint proxy statement/prospectus, or desire additional copies of this joint proxy statement/prospectus or additional proxies, contact Arch’s proxy solicitors:

Innisfree M&A Incorporated

501 Madison Avenue, 20th Floor, New York, NY 10022

Banks and Brokers Call Collect: (212) 750-5833

All Others Call Toll-Free: (877) 717-3905

or

D.F. King & Co., Inc.

48 Wall Street, 22nd Floor, New York, NY 10005

Banks and Brokers Call Collect: (212) 269-5550

All Others Call Toll-Free: (800) 848-3410

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RISK FACTORS

In addition to the other information contained in or incorporated by reference herein, including the matters addressed in the section entitled “Cautionary Statement Regarding Forward-Looking Statements,” you should carefully consider the following risks before deciding how to vote. You should also consider the other information in this joint proxy statement/prospectus and the other documents incorporated by reference herein, particularly the risk factors contained in CONSOL’s and Arch’s Annual Reports on Form 10-K and Quarterly Reports on Form 10-Q. For additional information, see the section entitled “Where You Can Find More Information.” In addition to the risks set forth below or referenced above, new risks may emerge from time to time and it is not possible to predict all risk factors, nor can CONSOL or Arch assess the impact of all factors on the merger and the combined company following the merger or the extent to which any factor or combination of factors may cause actual results to differ materially from those contained in or implied by any forward-looking statements.

Risks Relating to the Merger

Because the exchange ratio is fixed and because the market prices of CONSOL common stock and Arch Class A common stock will fluctuate, Arch stockholders cannot be certain of the market value of the merger consideration they will receive in the merger or the difference between the market value of the merger consideration they will receive in the merger and the market value of Arch common stock immediately prior to the merger.

At the time the merger is completed, each issued and outstanding eligible share of Arch common stock will be converted into the right to receive the merger consideration of 1.326 shares of CONSOL common stock, with cash paid in lieu of the issuance of any fractional shares of CONSOL common stock. The exchange ratio for the merger consideration is fixed, and there will be no adjustment to the merger consideration, regardless of whether the market price of CONSOL common stock or Arch Class A common stock changes prior to the completion of the merger. The market prices of CONSOL common stock and Arch Class A common stock have fluctuated since the date on which CONSOL and Arch announced they had entered into the merger agreement and will continue to fluctuate from the date of this joint proxy statement/prospectus to the date(s) of the CONSOL special meeting and the Arch special meeting, and the date on which Arch stockholders that are entitled to receive the merger consideration actually receive the merger consideration. The market prices of CONSOL common stock and Arch Class A common stock will fluctuate during and after these periods as a result of a variety of factors, including general market and economic conditions, changes in CONSOL’s and Arch’s respective businesses, operations and prospects, market assessments of the likelihood that the merger will be completed and regulatory considerations. Such factors are difficult to predict and in many cases may be beyond the control of CONSOL and Arch. Consequently, at the time Arch stockholders must decide whether to approve the Arch proposals, they will not know the market value of the merger consideration they will receive in the merger, which will depend on the market value of the shares of CONSOL common stock as of the effective time of merger.

In addition, Arch stockholders will not know the difference between the market value of the merger consideration they will receive in the merger and the market value of Arch Class A common stock immediately prior to the merger, which will depend on the market value of CONSOL common stock and Arch Class A common stock as of the effective time of the merger. Unless otherwise mutually agreed to in writing between CONSOL and Arch, the completion of the merger will take place on the third business day immediately following the satisfaction or waiver of the conditions to the completion of the merger (other than any such conditions which by their nature cannot be satisfied until the closing date, which will be required to be so satisfied or (to the extent permitted by applicable law) waived in accordance with the merger agreement on the closing date). Arch stockholders should obtain current stock price quotations for shares of CONSOL common stock and Arch Class A common stock before voting their shares of Arch common stock. For additional information about the merger consideration, see the sections entitled “The Merger—Consideration to Arch Stockholders” and “The Merger Agreement—Effect of the Merger on Capital Stock; Merger Consideration.”

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CONSOL stockholders and Arch stockholders, in each case as of immediately prior to the merger, will have reduced ownership in the combined company and less influence over management.

Based on the number of issued and outstanding shares of Arch common stock as of November 8, 2024 and the number of outstanding Arch equity awards currently estimated to be payable in shares of CONSOL common stock in connection with the merger, CONSOL anticipates issuing up to approximately 24,749,240 shares of CONSOL common stock pursuant to the merger agreement. The actual number of shares of CONSOL common stock to be issued pursuant to the merger agreement will be determined at the completion of the merger based on the number of shares of Arch common stock outstanding immediately prior to such time and the number of issued and outstanding Arch equity awards payable in shares of CONSOL common stock in connection with the merger.

Immediately after the completion of the merger, it is expected that CONSOL stockholders as of immediately prior to the merger will own approximately 55%, and Arch stockholders as of immediately prior to the merger will own approximately 45%, of the issued and outstanding shares of CONSOL common stock (in each case based on fully diluted shares outstanding of each company), which will trade on the NYSE under the ticker symbol “CNR” following the completion of the merger. As a result, current CONSOL stockholders and current Arch stockholders will have less influence on the management and policies of the combined company than they currently have on the management and policies of CONSOL and Arch, respectively.

The merger may not be accretive to certain financial metrics, which may negatively affect the market price of CONSOL common stock.

Preliminary financial estimates used in projected accretion to free cash flow may materially change. CONSOL and Arch may encounter additional transaction and integration-related costs, may fail to realize all of the benefits anticipated in the merger or may be subject to other factors that affect preliminary estimates. Any of these factors could decrease or delay the expected effect of the merger and contribute to a decrease in the market price of common stock of the combined company.

In addition, the issuance of new shares pursuant to the merger agreement could have the effect of depressing the market price of common stock of the combined company, through dilution of earnings per share or otherwise. Any dilution of, or delay of any accretion to, CONSOL’s earnings per share could cause the price of CONSOL common stock to decline or increase at a reduced rate.

The merger may not be completed, and the merger agreement may be terminated in accordance with its terms.

The merger is subject to a number of conditions that must be satisfied or waived prior to the completion of the merger, which are described in the section entitled “The Merger Agreement—Conditions to the Completion of the Merger.” These conditions to the completion of the merger may not be satisfied or waived in a timely manner or at all, and, accordingly, the merger may be delayed or may not be completed.

In addition, if the merger is not completed by August 20, 2025 (which date may be extended to November 20, 2025 in certain circumstances), either CONSOL or Arch may choose not to proceed with the merger by terminating the merger agreement, and the parties can mutually decide to terminate the merger agreement at any time, before or after stockholder approval. In addition, CONSOL and Arch may elect to terminate the merger agreement in certain other circumstances as further detailed in the section entitled “The Merger Agreement—Termination.”

The merger agreement limits CONSOL’s ability and Arch’s ability to pursue alternatives to the merger, may discourage other companies from trying to acquire CONSOL or Arch and, in specified circumstances, could require CONSOL or Arch to pay the other party a termination fee.

The merger agreement contains provisions that may discourage a third party from submitting a CONSOL competing proposal or an Arch competing proposal that might result in greater value to their respective

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stockholders than the merger, or may result in a potential acquirer of CONSOL, or a potential competing acquirer of Arch, proposing to pay a lower per share price to acquire CONSOL or Arch, respectively, than it might otherwise have proposed to pay. These provisions include a general prohibition on CONSOL and Arch from soliciting or, subject to certain exceptions relating to the exercise of fiduciary duties by the CONSOL board or the Arch board, entering into discussions with any third party regarding any CONSOL competing proposal or Arch competing proposal. Further, even if the CONSOL board or the Arch board withholds, withdraws, qualifies or modifies its recommendation to stockholders with respect to the CONSOL issuance proposal or the CONSOL charter amendment proposal, in the case of the CONSOL board, or the Arch merger proposal, in the case of the Arch board, unless the merger agreement has been terminated in accordance with its terms, each of CONSOL and Arch will still be required to submit the CONSOL issuance proposal and the CONSOL charter amendment proposal, in the case of the CONSOL board, and the Arch merger proposal, in the case of the Arch board, to a vote by the CONSOL stockholders and Arch stockholders, respectively. The merger agreement further provides that under specified circumstances, including after a change of recommendation by either party’s board of directors and a subsequent termination of the merger agreement by the other party in accordance with its terms, CONSOL or Arch, as applicable, may be required to pay the other party a cash termination fee of $82 million. In addition, if the merger agreement is terminated under specified circumstances, CONSOL or Arch, as applicable, may be required to pay the other party a cash termination fee of $82 million if it enters into an agreement for a CONSOL competing proposal or Arch competing proposal, as applicable, within nine months following such termination. For additional information, see the sections entitled “The Merger Agreement—No Solicitation; Changes of Recommendation” and “The Merger Agreement—Termination.”

Failure to complete the merger could negatively impact the price of shares of CONSOL common stock and the price of shares of Arch Class A common stock, as well as CONSOL’s and Arch’s respective future businesses and financial results.

The merger agreement contains a number of conditions that must be satisfied or waived prior to the completion of the merger, which are described in the section entitled “The Merger Agreement—Conditions to the Completion of the Merger.” There can be no assurance that all of the conditions to the completion of the merger will be satisfied or waived. If these conditions are not satisfied or waived, CONSOL and Arch will be unable to complete the merger.

If the merger is not completed for any reason, including the failure to receive the required approvals of the CONSOL stockholders or the Arch stockholders, CONSOL’s and Arch’s respective businesses and financial results may be adversely affected and, without realizing any of the benefits of having completed the merger, CONSOL and Arch would be subject to a number of risks, including as follows:

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In addition to the above risks, if the merger agreement is terminated and either party’s board seeks an alternative transaction, the holders of such party’s common stock cannot be certain that such party will be able to find a party willing to engage in a transaction on more attractive terms than the merger. If the merger agreement is terminated under specified circumstances, either CONSOL or Arch may be required to pay the other party a termination fee or other termination-related payment. For a description of these circumstances, see the section entitled “The Merger Agreement—Termination.”

Directors and executive officers of each party may have interests in the merger that may be different from, or in addition to, the interests of CONSOL stockholders and Arch stockholders generally.

In considering the recommendation of (1) the CONSOL board that CONSOL stockholders vote in favor of the proposals on the agenda for the CONSOL special meeting or (2) the Arch board that Arch stockholders vote in favor of the proposals on the agenda for the Arch special meeting, as applicable, CONSOL stockholders and Arch stockholders should be aware of and take into account the fact that certain CONSOL and Arch directors and executive officers have interests in the merger that may be different from, or in addition to, the interests of CONSOL stockholders and Arch stockholders generally. The interests of CONSOL’s directors and executive officers include, among others, immediate vesting of certain equity or equity-based awards in connection with the merger, and certain change-in-control severance benefits, in the event of termination or constructive termination during specified time periods following the consummation of the merger, as further described in the section entitled “The Merger—Interests of CONSOL Directors and Executive Officers in the Merger.” The interests of Arch’s directors and executive officers include, among others, immediate vesting of equity or equity-based awards in connection with the merger, change-in-control severance benefits, in the event of termination or constructive termination prior to or during specified time periods following the consummation of the merger, and rights to continuing indemnification and directors’ and officers’ liability insurance, as further described in the section entitled “The Merger—Interests of Arch Directors and Executive Officers in the Merger.” The CONSOL board and the Arch board were aware of and considered the interests of their respective directors and officers, among other matters, in evaluating the terms and structure, and overseeing the negotiation of the merger, in approving the merger agreement and the transactions contemplated thereby, including the merger, and the recommendation of (1) the CONSOL board that CONSOL stockholders vote in favor of the proposals on the agenda for the CONSOL special meeting and (2) the Arch board that Arch stockholders vote in favor of the proposals on the agenda for the Arch special meeting.

The unaudited pro forma condensed combined financial statements and unaudited prospective financial information included in this joint proxy statement/prospectus are preliminary and future results of CONSOL or Arch may differ, possibly materially.

The unaudited pro forma condensed combined financial statements and unaudited prospective financial information contained in this joint proxy statement/prospectus are based on a variety of adjustments, assumptions and preliminary estimates and may not be indicative of the financial position or results of operations of the combined company following the merger for several reasons. Specifically, the unaudited pro forma condensed combined financial statements do not reflect the effect of any integration costs or any changes in CONSOL’s debt to capitalization ratio following the completion of the merger. In addition, the unaudited pro forma condensed combined financial statements have been prepared with the assumption that CONSOL will be identified as the acquirer under accounting principles generally accepted in the United States of America (“GAAP”) and reflect adjustments based upon preliminary estimates of the fair value of assets to be acquired and liabilities to be assumed. For additional information, see the section entitled “Unaudited Pro Forma Condensed Combined Financial Statements.” In addition, the merger and post-merger integration process may give rise to unexpected liabilities and costs, including costs associated with the defense and resolution of transaction-related litigation or other claims. Unexpected delays in completing the merger or in connection with the post-merger integration process may significantly increase the related costs and expenses incurred by the combined company. The actual financial position, financial performance and results of operations of the combined company following the merger may not be consistent with, or evident from, the unaudited pro forma condensed combined

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financial statements or prospective financial information included in this joint proxy statement/prospectus. In addition, the assumptions, including those regarding the future operating and financial performance of the combined company and future commodity prices, used in preparing the unaudited pro forma condensed combined financial statements and prospective financial information included in this joint proxy statement/prospectus may not prove to be accurate and may be affected by other factors. See “Risk Factors—Risks Relating to the Combined Company Following Completion of the Merger—The market price of CONSOL common stock after the completion of the merger may be affected by factors different from those that historically have affected or currently affect CONSOL common stock and Arch Class A common stock.” Any potential decline in the financial condition or results of operations of the combined company may cause significant variations in the price of the common stock of the combined company. For more information, see the unaudited pro forma condensed combined financial statements contained in this joint proxy statement/prospectus.

The opinions of CONSOL’s and Arch’s respective financial advisors do not reflect changes in circumstances between the signing of the merger agreement and the completion of the merger.

CONSOL and Arch have received opinions from their respective financial advisors in connection with the signing of the merger agreement, but have not obtained updated opinions from their respective financial advisors as of the date of this joint proxy statement/prospectus. Changes in the operations and prospects of CONSOL or Arch, general market and economic conditions and other factors that may be beyond the control of CONSOL or Arch, and on which CONSOL’s and Arch’s financial advisors’ opinions were based, may significantly alter the value of CONSOL or Arch or the prices of the shares of CONSOL common stock or Arch Class A common stock by the time the merger is completed. The opinions do not speak as of the time the merger will be completed or as of any date other than the date of such opinions. Because CONSOL and Arch do not currently anticipate asking their respective financial advisors to update their opinions, the opinions will not address the fairness of the merger consideration or the exchange ratio, as applicable, from a financial point of view at the time the merger is completed. The CONSOL board’s recommendation that CONSOL stockholders vote in favor of the proposals on the agenda for the CONSOL special meeting and the Arch board’s recommendation that Arch stockholders vote in favor of the proposals on the agenda for the Arch special meeting, however, are made as of the date of this joint proxy statement/prospectus.

For a description of the opinions that CONSOL and Arch received from their respective financial advisors, see the sections entitled “The Merger—Opinion of Moelis & Company LLC, CONSOL’s Financial Advisor” and “The Merger—Opinion of Perella Weinberg Partners LP, Arch’s Financial Advisor.” A copy of the opinion of Moelis, CONSOL’s financial advisor, is attached as Annex B to this joint proxy statement/prospectus, and a copy of the opinion of PWP, Arch’s financial advisor, is attached as Annex C to this joint proxy statement/prospectus, and each is incorporated by reference herein in its entirety.

The financial forecasts relating to CONSOL and Arch prepared in connection with the merger are based on various estimates and assumptions that may not be realized, which may adversely affect the market price of common stock of the combined company following the closing of the merger.

This joint proxy statement/prospectus includes certain financial forecasts considered by CONSOL and Arch in connection with their respective businesses. None of the financial forecasts prepared by CONSOL or Arch were prepared with a view towards public disclosure or compliance with the published guidelines of the SEC, GAAP or the guidelines established by the American Institute of Certified Public Accountants or any other regulatory or professional body for the preparation and presentation of financial forecasts. These forecasts are inherently based on various estimates and assumptions that are subject to the judgment of those preparing them. These forecasts are also subject to significant economic, competitive, industry and other uncertainties and contingencies, all of which are difficult or impossible to predict and many of which are beyond the control of CONSOL and Arch. Important factors that may affect the actual results of CONSOL and Arch and cause the internal financial forecasts to not be achieved include risks and uncertainties relating to CONSOL’s and Arch’s businesses, industry performance, the regulatory environment, general business and economic conditions and other factors referred to under the section entitled “Cautionary Statement Regarding Forward-Looking Statements.” In view of

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these uncertainties, the inclusion of financial forecasts in this joint proxy statement/prospectus is not and should not be viewed as a representation that the forecasted results will necessarily reflect actual future results.

In addition, the financial forecasts also reflect assumptions that are subject to change and do not reflect revised prospects for CONSOL’s and Arch’s businesses, changes in general business or economic conditions or any other transaction or event that has occurred or that may occur and that was not anticipated at the time the financial forecasts were prepared. Further, any forward-looking statement speaks only as of the date on which it is made, and neither CONSOL nor Arch undertakes any obligation, other than as required by applicable law, to update the financial estimates to reflect events or circumstances after the dates as of which the financial estimates were prepared or to reflect the occurrence of anticipated or unanticipated events or circumstances. In addition, since such financial forecasts cover multiple years, and the underlying information by its nature becomes less predictive with each successive year, there can be no assurance that CONSOL’s, Arch’s or the combined company’s financial condition or results of operations will be consistent with those set forth in such forecasts.

Uncertainties associated with the merger may cause a loss of management personnel and other key employees of CONSOL and Arch, which could adversely affect the future business and operations of the combined company following the merger.

Each of CONSOL and Arch depends on the experience and industry knowledge of its officers and other key employees to execute its business plans. The success of the combined company after the merger will depend in part on its ability to retain key management personnel and other key employees. Current and prospective employees of CONSOL and Arch may experience uncertainty about their roles within the combined company following the merger or other concerns regarding the timing and completion of the merger or the operations of the combined company following the merger, any of which may have an adverse effect on the ability of CONSOL and Arch to retain or attract key management and other key personnel. If CONSOL or Arch is unable to retain personnel, including CONSOL’s or Arch’s key management, who are critical to the future operations of the companies, CONSOL and Arch could face disruptions in their operations, loss of existing customers, loss of key information, expertise or know-how and unanticipated additional recruitment and training costs. In addition, the loss of key CONSOL and Arch personnel could diminish the anticipated benefits of the merger. No assurance can be given that the combined company, following the merger, will be able to retain or attract key management personnel and other key employees of CONSOL and Arch to the same extent that CONSOL and Arch have previously been able to retain or attract their own employees.

The business relationships of CONSOL and Arch may be subject to disruption due to uncertainty associated with the merger, which could have a material effect on the business, financial condition, cash flows and results of operations of CONSOL or Arch pending the combined company and following the merger.

Parties with which CONSOL or Arch do business may experience uncertainty associated with the merger, including with respect to current or future business relationships with CONSOL or Arch following the merger. CONSOL’s and Arch’s business relationships may be subject to disruption as customers, distributors, suppliers, vendors, landlords, joint venture participants and other third parties with whom they do business 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 CONSOL or Arch following the merger. These disruptions could have a material and adverse effect on the business, financial condition, cash flows and results of operations, of CONSOL or Arch, regardless of whether the merger is completed, as well as a material and adverse effect on the combined company’s ability to realize the expected cost savings and other benefits of the merger. The risk, and adverse effects, of any disruption could be exacerbated by a delay in completion of the merger or termination of the merger agreement.

Completion of the merger may trigger change-in-control, right of first refusal or other provisions in certain agreements to which CONSOL or Arch is a party.

The completion of the merger may trigger change-in-control, right of first refusal or other provisions in certain agreements to which CONSOL or Arch is a party. If CONSOL and Arch are unable to negotiate waivers of those

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provisions, the counterparties may exercise their rights and remedies under the applicable agreements, including in some instances potentially terminating the agreements or seeking monetary damages. Even if CONSOL and Arch are able to negotiate waivers, the counterparties may require a fee for such waivers or seek to renegotiate the agreements on terms less favorable to the combined company.

In addition, in connection with the merger, CONSOL and Arch have agreed that the merger will constitute a “change in control,” “change of control,” or term of similar import under each applicable Arch plan and under each change-in-control agreement between CONSOL and certain of its officers as described in more detail in the sections entitled “The Merger—Interests of CONSOL Directors and Executive Officers in the Merger” and “The Merger—Interests of Arch Directors and Executive Officers in the Merger.”

CONSOL or Arch may waive one or more of the closing conditions without re-soliciting stockholder approval.

CONSOL or Arch may determine to waive, in whole or part, one or more of the conditions to closing the merger prior to CONSOL or Arch, as the case may be, being obligated to consummate the merger. Each of CONSOL and Arch currently expects to evaluate the materiality of any waiver and its effect on its respective stockholders in light of the facts and circumstances at the time of any such waiver in order to determine whether any amendment of this joint proxy statement/prospectus or any re-solicitation of proxies is required in light of such waiver. Any determination whether to waive any condition to the merger or to re-solicit stockholder approval or amending or supplementing this joint proxy statement/prospectus as a result of any such waiver will be made by CONSOL or Arch at the time of such waiver based on the facts and circumstances as they exist at that time.

The merger agreement subjects CONSOL and Arch to restrictions on their respective business activities prior to the effective time of the merger.

The merger agreement restricts CONSOL and Arch from entering into certain corporate transactions and taking other specified actions without the consent of the other party, and generally requires each party to continue its operations in the ordinary course through the completion of the merger. These restrictions could be in place for an extended period of time if completion of the merger is delayed and could prevent CONSOL and Arch from pursuing attractive business opportunities that may arise prior to the completion of the merger. For a description of the restrictive covenants to which CONSOL and Arch are subject, see the section entitled “The Merger Agreement—Interim Operations of Arch and CONSOL Pending the Merger.”

CONSOL and Arch are expected to incur significant costs in connection with the merger and integration of the two companies, which may be in excess of those anticipated by CONSOL or Arch.

Each of CONSOL and Arch has incurred and expects to continue to incur a number of non-recurring costs associated with negotiating and completing the merger and combining the operations of the two companies. These expenses have been, and will continue to be, substantial. The substantial majority of non-recurring expenses will consist of transaction costs related to the merger and include, among others, employee retention costs, fees paid to financial, legal and accounting advisors, severance and benefit costs, filing fees and debt restructuring costs. Many of these costs will be borne by CONSOL or Arch even if the merger is not completed.

CONSOL and Arch will also incur transaction costs related to formulating and implementing integration plans, including facilities and systems consolidation costs and employment-related costs. CONSOL and Arch will continue to assess the magnitude of these costs, and additional unanticipated costs may be incurred in connection with the merger and the integration of the two companies’ businesses. Although CONSOL and Arch each expect that the elimination of duplicative costs, as well as the realization of other efficiencies related to the integration of the businesses, should allow the combined company to offset integration-related costs over time, this net benefit may not be achieved in the near term, or at all. For additional information, see the risk factor entitled “—The failure to integrate the businesses and operations of CONSOL and Arch successfully in the expected time frame may adversely affect the combined company’s future results” below. The costs described above, as well as

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other unanticipated costs and expenses, could adversely effect the financial condition, cash flows and operating results of the combined company following the completion of the merger.

If the merger does not qualify as a “reorganization” within the meaning of Section 368(a) of the Code, Arch stockholders may be required to pay substantial U.S. federal income taxes.

The merger is intended to qualify as a “reorganization” within the meaning of Section 368(a) of the Code, and it is a condition to the obligation of Arch to complete the merger that Arch receives an opinion from external counsel, dated as of the closing date, to the effect that, on the basis of facts, representations and assumptions set forth or referred to in such opinion, the merger should qualify as a “reorganization” within the meaning of Section 368(a) of the Code. The foregoing opinion of counsel will be based on, among other things, certain representations made by CONSOL and Arch and certain assumptions, all of which must be consistent with the state of facts existing at the time of the merger. If any of these representations and assumptions are, or become, inaccurate or incomplete, such opinion may be invalid, and the conclusions reached therein could be jeopardized. In addition, such opinion of counsel is not free from doubt because there is no authority directly addressing the treatment of all of the particular facts of the merger for U.S. federal income tax purposes. An opinion of counsel represents counsel’s best legal judgment and is not binding on the IRS or the courts, which may not agree with the conclusions set forth in such opinion. If the merger does not qualify as a “reorganization” within the meaning of Section 368(a) of the Code, a U.S. holder of Arch common stock would generally recognize capital gain or loss on the exchange of its Arch common stock for CONSOL common stock and cash in lieu of fractional shares of CONSOL common stock pursuant to the merger. For more information, see the section titled “Material U.S. Federal Income Tax Consequences of the Merger.”

Litigation relating to the merger, if any, could result in an injunction preventing the completion of the merger and/or substantial costs to CONSOL and Arch.

Securities class action lawsuits and derivative lawsuits are often brought against public companies that have entered into acquisition, merger or other business combination agreements like the merger agreement. 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 CONSOL’s and Arch’s respective liquidity and financial condition. Lawsuits that may be brought against CONSOL, Arch 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 merger. One of the conditions to the closing of the merger is that no injunction by any governmental entity having jurisdiction over CONSOL, Arch or Merger Sub has been entered and continues to be in effect and no law has been adopted, in either case, that prohibits the closing of the merger. Consequently, if a plaintiff is successful in obtaining an injunction prohibiting completion of the merger, that injunction may delay or prevent the merger from being completed within the expected timeframe or at all, which may adversely affect CONSOL’s and Arch’s respective businesses, financial condition, cash flows and results of operations. In addition, either CONSOL or Arch may terminate the merger agreement if any governmental entity having jurisdiction over CONSOL, Arch or Merger Sub has issued any order, decree, ruling or injunction permanently prohibiting the closing of the merger that has become final and nonappealable or if any law has been adopted that permanently prohibits the closing of the merger, so long as CONSOL’s or Merger Sub’s (in the case of a termination by CONSOL) or Arch’s (in the case of a termination by Arch) failure to fulfill any material covenant or agreement under the merger agreement has not been the cause of, materially contributed to or resulted in such order, decree, ruling, injunction or other action.

There can be no assurance that any of the defendants would be successful in the outcome of any potential future lawsuits. The defense or settlement of any lawsuit or claim that remains unresolved at the time the merger is completed may adversely affect the combined company’s business, financial condition, cash flows and results of operations.

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CONSOL stockholders and holders of Arch Class A common stock will not be entitled to appraisal rights in the merger.

Appraisal rights (also known as dissenters’ rights) are statutory rights that enable stockholders to dissent from certain extraordinary transactions, such as certain mergers, and to demand that the corporation pay the fair value for their shares as determined by a court in a judicial proceeding instead of receiving the consideration offered to stockholders in connection with the applicable transaction. Under Section 262 of the DGCL, CONSOL stockholders and holders of Arch Class A common stock are not entitled to appraisal rights in connection with the merger or the issuance of common stock of the combined company in connection with the merger. However, holders of the 257 shares of Arch Class B common stock currently issued and outstanding are entitled to appraisal rights under Section 262 of the DGCL. For more information, see the section entitled “Appraisal Rights” on page 213.

Risks Relating to the Combined Company Following Completion of the Merger

The market price of CONSOL common stock will continue to fluctuate after the merger.

Upon completion of the merger, Arch stockholders who receive merger consideration will become holders of shares of CONSOL common stock which will trade on the NYSE under the ticker symbol “CNR.” The market price of CONSOL common stock may fluctuate significantly following completion of the merger, and holders of CONSOL common stock could lose some or all of the value of their investment. In addition, the stock market has experienced significant price and volume fluctuations in recent times, which, if they continue to occur, could adversely effect the market for, or liquidity of, CONSOL common stock, regardless of CONSOL’s actual operating performance.

The market price of CONSOL common stock after the completion of the merger may be affected by factors different from those that historically have affected or currently affect CONSOL common stock and Arch Class A common stock.

Upon completion of the merger, Arch stockholders who receive merger consideration will become holders of CONSOL common stock, which will trade on the NYSE under the ticker symbol “CNR.” CONSOL’s business differs from that of Arch and certain adjustments may be made to the combined company as a result of this merger of equals transaction. The financial position of the combined company after completion of the merger may differ from CONSOL’s financial position before the completion of the merger, and the results of operations and/or cash flows of CONSOL after the completion of the merger may be affected by factors different from those currently affecting the financial position or results of operations and/or cash flows of CONSOL and Arch, respectively. For example, the market price of Arch Class A common stock may be more sensitive to changes in metallurgical coal commodity prices currently than is the market price of CONSOL common stock currently, and the market price of CONSOL common stock may be more sensitive to changes in thermal coal commodity prices currently than is the market price of Arch Class A common stock currently. Accordingly, the market price of CONSOL common stock after the completion of the merger may be affected by factors different from those currently affecting the market prices of CONSOL common stock and Arch Class A common stock, respectively, in the absence of the merger. In addition, general fluctuations in stock markets could adversely effect the market for, or liquidity of, CONSOL common stock, regardless of the combined company’s actual operating performance. For a discussion of the businesses of CONSOL and Arch and of some important factors to consider in connection with those businesses, see the section entitled “Information About the Companies” and the documents incorporated by reference in the section entitled “Where You Can Find More Information,” including, in particular, in the sections entitled “Risk Factors” in each of CONSOL’s and Arch’s Annual Report on Form 10-K for the year ended December 31, 2023 and Quarterly Reports on Form 10-Q for the quarterly periods ended March 31, 2024, June 30, 2024 and September 30, 2024.

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The failure to integrate the businesses and operations of CONSOL and Arch successfully in the expected time frame may adversely affect the combined company’s future results.

CONSOL and Arch have operated and, until the completion of the merger, will continue to operate independently. Following the completion of the merger, their respective businesses may not be integrated successfully. It is possible that the integration process could result in the loss of key CONSOL employees or key Arch employees; the loss of customers, service providers, vendors or other business counterparties, the disruption of either company’s or both companies’ ongoing businesses, inconsistencies in standards, controls, procedures and policies, potential unknown liabilities and unforeseen expenses, delays, or regulatory conditions associated with and following completion of the merger; or higher-than-expected integration costs and an overall post-completion integration process that takes longer than originally anticipated. Specifically, the following challenges, among others, must be addressed in integrating the operations of CONSOL and Arch in order to realize the anticipated benefits of the merger:

In addition, at times the attention of certain members of either company’s or both companies’ management and resources may be focused on completion of the merger and the integration of the businesses of the two companies and diverted from day-to-day business operations or other opportunities that may be beneficial, which may disrupt each company’s ongoing operations and the operations of the combined company. Furthermore, following the merger, the board of directors and executive leadership of the combined company will consist of former directors from each of CONSOL and Arch and former executive officers from each of CONSOL and Arch, respectively. Combining the boards of directors and management teams of each company into a single board and a single management team could require the reconciliation of differing priorities and philosophies.

The merger may result in a loss of customers, distributors, service providers, suppliers, vendors, joint venture participants and other business counterparties, and may result in the termination of existing contracts.

Following the merger, some of the customers, distributors, service providers, suppliers, vendors, joint venture participants and other business counterparties of CONSOL or Arch may terminate or scale back their current or prospective business relationships with the combined company. In addition, CONSOL and Arch have contracts with customers, distributors, service providers, suppliers, vendors, joint venture participants and other business counterparties that may require CONSOL or Arch to obtain consents from these other parties in connection with

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the merger, which may not be obtained on favorable terms or at all. If relationships with customers, distributors, service providers, suppliers, vendors, joint venture participants and other business counterparties are adversely affected by the merger, or if the combined company, following the merger, loses the benefits of the contracts of CONSOL or Arch, the business, financial condition, cash flows and results of operations of the combined company could be adversely affected.

Each of CONSOL and Arch may have liabilities that are not known to the other party.

Each of CONSOL and Arch may have liabilities that the other party failed, or was unable, to discover in the course of performing its respective due diligence investigations. CONSOL and Arch may learn additional information about the other party that materially adversely affects it, such as unknown or contingent liabilities and liabilities related to compliance with applicable laws. As a result of these factors, the combined company may incur additional costs and expenses and may be forced to later write-down or write-off assets, restructure operations or incur impairment or other charges that could result in the combined company reporting losses. Even if CONSOL’s and Arch’s respective due diligence has identified certain risks, unexpected risks may arise and previously known risks may materialize in a manner not consistent with its expectations. If any of these risks materialize, this could adversely effect the combined company’s financial condition and results of operations and could contribute to negative market perceptions about, or price movements of, CONSOL common stock following the merger.

The combined company may fail to realize all of the anticipated benefits of the merger.

The success of the merger will depend, in part, on CONSOL’s ability to realize the anticipated benefits and cost savings from combining CONSOL’s and Arch’s businesses and operational synergies. The anticipated benefits and cost savings of the merger may not be realized fully or at all, may take longer to realize than expected, may not be realized or could have other adverse effects that CONSOL does not currently foresee, in which case, among other things, the merger may not be accretive to free cash flow and may not generate significant discretionary cash flow to return to stockholders via share buybacks or other means. Some of the assumptions that CONSOL and Arch have made, such as the achievement of the anticipated benefits related to the geographic, commodity and asset diversification and the expected size, scale, inventory and financial strength of the combined company, may not be realized. The integration process may, for each of CONSOL and Arch, result in the loss of key employees, the disruption of ongoing businesses or inconsistencies in standards, controls, procedures and policies. In addition, there could be potential unknown liabilities and unforeseen expenses associated with the merger that could adversely impact the combined company.

The provisions of the debt agreements of the combined company and the risks associated with the combined company’s debt could adversely affect the combined company and its financial condition, liquidity and results of operations.

As of September 30, 2024, CONSOL’s total outstanding indebtedness was approximately $187 million, including amounts outstanding under its credit facilities and revenue bonds. As of September 30, 2024, Arch’s total outstanding indebtedness was approximately $127 million, including amounts outstanding under its credit facilities and tax-exempt bonds. The merger is expected to be a change in control event that would accelerate the repayment of, or require the making of an offer to purchase, certain outstanding debt obligations of Arch. CONSOL and/or Arch may seek to repay, refinance, repurchase, redeem, exchange or otherwise terminate CONSOL’s existing indebtedness and/or Arch’s existing indebtedness prior to, in connection with or following the completion of the merger. If CONSOL and Arch do seek to refinance CONSOL’s existing indebtedness and/or Arch’s existing indebtedness, there can be no guarantee that CONSOL and/or Arch would be able to execute the refinancing on favorable terms or at all. Any increase in the indebtedness of the combined company could have adverse effects on its financial condition, cash flows and results of operations, including by:

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In connection with any debt refinancing related to the merger, it is anticipated that CONSOL and Arch would seek ratings of the indebtedness of the combined company from one or more nationally recognized credit rating agencies. While S&P Global Ratings issued a report following the announcement of the merger stating that CONSOL’s credit ratings were on a CreditWatch with positive implications that indicates the possibility of an upgrade based on the combined company’s expected credit profile, there can be no guarantee that S&P Global Ratings or other nationally recognized credit rating agencies will upgrade the combined company’s credit ratings following the merger. Such credit ratings would reflect each rating organization’s opinion of the combined company’s financial strength, operating performance and ability to meet its debt obligations. Such credit ratings would affect the cost and availability of future borrowings and, accordingly, its cost of capital. There can be no assurance that the combined company will achieve a particular rating or maintain a particular rating in the future.

The future results of the combined company following the merger will suffer if the combined company does not effectively manage its expanded operations.

Following the merger, the size, geographic footprint and complexity of the combined company will increase significantly compared to the business of each of CONSOL and Arch. The combined company’s future success will depend, in part, upon its ability to manage this expanded business, which will pose substantial challenges for management, including challenges related to the management and monitoring of new operations and geographies and associated increased costs and complexity. The combined company may also face increased scrutiny from, and/or additional regulatory requirements of, governmental authorities as a result of the significant increase in the size, geographic footprint and complexity of its business. There can be no assurances that the combined company will be successful or that it will realize the expected operating efficiencies, cost savings or other benefits currently anticipated from the merger.

There is no guarantee that CONSOL will continue to declare and pay dividends or repurchase shares of CONSOL common stock following the merger.

Although each of CONSOL and Arch has returned capital to its respective stockholders in the past, through a combination of cash dividends on, and repurchases of, its respective shares of common stock, the board of directors of the combined company may determine not to declare dividends, repurchases shares of its common stock or use other means to return capital to its stockholders in the future or may reduce the amount of capital returned to its stockholders through dividends, share repurchases and other means in the future. Decisions on whether, when, by what means and in what amounts to return capital to its stockholders will remain in the discretion of the board of directors of the combined company (as reconstituted following the merger). Any dividend payment or share repurchase amounts will be determined by the board of directors of the combined company on a quarterly basis, and it is possible that the board of directors of the combined company may increase or decrease the amount of dividends paid or shares repurchased in the future, or determine not to declare dividends and/or repurchase shares in the future, at any time and for any reason. CONSOL and Arch expect that any such decisions will depend on the combined company’s financial condition, results of operations, cash

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balances, cash requirements, future prospects, the outlook for commodity prices and other considerations that the board of directors of the combined company deems relevant, including, but not limited to:

Stockholders should be aware that they have no contractual or other legal right to dividends that have not been declared. For additional information, see the section entitled “The Merger—Dividend Policy.”

The combined company may record goodwill and other intangible assets that could become impaired and result in material non-cash charges to the results of operations of the combined company in the future.

In accordance with Accounting Standards Codification Topic 805, Business Combinations (“ASC 805”), the merger will be accounted for as an acquisition by CONSOL pursuant to the acquisition method of accounting for business combinations. Under the acquisition method of accounting, CONSOL will record the net tangible and identifiable intangible assets and liabilities of Arch and its subsidiaries as of the consummation of the merger, at their respective fair values. The reported financial condition and results of operations of CONSOL for periods after consummation of the merger will reflect Arch balances and results after consummation of the merger but will not be restated retroactively to reflect the historical financial position or results of operations of Arch and its subsidiaries for periods prior to the merger. For additional information, see the section entitled “Unaudited Pro Forma Condensed Combined Financial Statements.”

Under the acquisition method of accounting, the total purchase price will be allocated to Arch’s tangible assets and liabilities and identifiable intangible assets based on their fair values as of the date of completion of the merger, with any excess purchase price allocated to goodwill. To the extent the value of goodwill or intangibles, if any, becomes impaired in the future, the combined company may be required to recognize material non-cash charges relating to such impairment. The combined company’s operating results may be significantly impacted from both the impairment and the underlying trends in the business that triggered the impairment.

CONSOL’s ability to utilize Arch’s historic net operating loss carryforwards and certain other tax attributes may be limited.

As of December 31, 2023, Arch had U.S. federal net operating loss carryforwards (“NOLs”) of approximately $319.3 million, $46.6 million of which is subject to expiration, if not utilized, starting in 2037. The remaining carryforwards do not expire. However, they can only be used to offset 80% of U.S. federal taxable income. CONSOL’s ability to utilize these NOLs and other tax attributes to reduce future taxable income following the closing of the merger depends on many factors, including its future income, which cannot be assured. Section 382 of the Code (“Section 382”) and Section 383 of the Code generally impose an annual limitation on the amount of NOLs and certain other tax attributes that may be used to offset taxable income when a corporation has undergone an “ownership change” (as determined under Section 382). An ownership change generally occurs if one or more stockholders (or groups of stockholders) who are each deemed to own at least 5% of such corporation’s stock increase their ownership by more than 50 percentage points over their lowest ownership percentage within a rolling three-year period. In the event that an ownership change occurs, utilization of Arch’s NOLs would be subject to an annual limitation under Section 382, generally determined by multiplying (1) the fair market value of its stock at the time of the ownership change by (2) the long-term tax-exempt rate published by the IRS for the month in which the ownership change occurs, subject to certain adjustments. Any unused annual limitation may be carried over to later years.

Arch presently anticipates that it would undergo an ownership change under Section 382 as a result of the merger, which would trigger a limitation (calculated as described above) on CONSOL’s ability to utilize Arch’s historic NOLs and could cause some of those NOLs to expire without being utilized.

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Shares of CONSOL common stock received by Arch stockholders as a result of the merger will have different rights from shares of Arch common stock.

Upon completion of the merger, Arch stockholders will no longer be stockholders of Arch, and Arch stockholders who receive merger consideration will become holders of CONSOL common stock, which will trade on the NYSE under the ticker symbol “CNR.” There will be important differences between the current rights of Arch stockholders and the rights to which such stockholders will be entitled as CONSOL stockholders. For a discussion of the different rights associated with shares of CONSOL common stock as compared to shares of Arch common stock, see the section entitled “Comparison of Stockholders’ Rights.”

Future sales or issuances of CONSOL common stock could have a negative impact on the CONSOL common stock price.

Based on the number of shares of Arch common stock outstanding as of November 8, 2024 and the number of outstanding Arch equity awards currently estimated to be settled in CONSOL common stock following the merger, CONSOL expects to issue up to approximately 24,749,240 shares of CONSOL common stock in connection with the merger. The CONSOL common stock that Arch stockholders will receive upon the exchange of Arch common stock for the merger consideration generally may be sold immediately in the public market. It is possible that some former Arch stockholders may seek to sell some or all of the shares of CONSOL common stock they receive as merger consideration, and the merger agreement contains no restriction on the ability of former Arch stockholders to sell such shares of CONSOL common stock following completion of the merger. Other CONSOL stockholders may also seek to sell shares of CONSOL common stock held by them following completion of the merger. These sales or other dispositions of a significant number of shares of CONSOL common stock (or the perception that such sales or other dispositions may occur), coupled with the increase in the outstanding number of shares of CONSOL common stock as a result of the merger (as well as any increase resulting from future issuances of CONSOL common stock), may affect the market for CONSOL common stock in an adverse manner and may cause the price of CONSOL common stock to fall.

The exclusive-forum provision contained in the CONSOL certificate of incorporation could limit its stockholders’ ability to obtain a favorable judicial forum for disputes with CONSOL or its directors, officers or other employees.

The CONSOL certificate of incorporation provides that, unless CONSOL consents in writing to the selection of an alternative forum, the sole and exclusive forum for (1) any derivative action or proceeding brought on behalf of CONSOL, (2) any action asserting a claim for or based on a breach of a fiduciary duty owed by any current or former director, officer, other employee or agent of CONSOL to CONSOL or its stockholders, (3) any action asserting a claim against CONSOL or any current or former director or officer or other employee of CONSOL arising pursuant to any provision of the DGCL or the CONSOL certificate of incorporation or the CONSOL bylaws or (4) any action asserting a claim related to or involving CONSOL governed by the internal affairs doctrine or asserting an “internal corporate claim” (as defined in Section 115 of the DGCL) shall, to the fullest extent permitted by law, be a state court sitting in the State of Delaware (or, if no state court located within the State of Delaware has jurisdiction, the federal court for the District of Delaware).

To the fullest extent permitted by applicable law, this exclusive-forum provision applies to state and federal law claims, including claims under the federal securities laws, including the Securities Act and the Exchange Act, although CONSOL stockholders will not be deemed to have waived CONSOL’s compliance with the federal securities laws and the rules and regulations thereunder. The enforceability of similar choice-of-forum provisions in other companies’ bylaws has been challenged in legal proceedings, and it is possible that, in connection with claims arising under federal securities laws or otherwise, a court could find the exclusive forum provision contained in the CONSOL bylaws to be inapplicable or unenforceable.

This exclusive-forum provision may limit the ability of a stockholder, including a former holder of Arch common stock who becomes a holder of CONSOL common stock after the merger is completed, to bring a claim

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in a judicial forum of its choosing for disputes with CONSOL or its directors, officers or other employees, which may discourage lawsuits against CONSOL and its directors, officers and other employees. Alternatively, if a court were to find this exclusive-forum provision inapplicable to, or unenforceable in respect of, one or more of the specified types of actions or proceedings described above, CONSOL may incur additional costs associated with resolving such matters in other jurisdictions, which could negatively affect CONSOL’s business, results of operations and financial condition. In addition, stockholders who do bring a claim in a state or federal court located within the State of Delaware could face additional litigation costs in pursuing any such claim, particularly if they do not reside in or near Delaware. In addition, the court located in the State of Delaware may reach different judgments or results than would other courts, including courts where a stockholder would otherwise choose to bring the action, and such judgments or results may be more favorable to CONSOL than to its stockholders.

Risks Relating to CONSOL’s Business

In addition to the risk factors described above relating to the combined company following completion of the merger, you should read and consider risk factors specific to CONSOL’s businesses that will also affect the combined company after the completion of the merger. These risks are described in Part I, Item 1A of CONSOL’s Annual Report on Form 10-K for the year ended December 31, 2023 and in Part II, Item 1A of CONSOL’s Quarterly Reports on Form 10-Q for the quarterly periods ended March 31, 2024, June 30, 2024 and September 30, 2024, and in other documents that are incorporated by reference herein. For the location of information incorporated by reference in this joint proxy statement/prospectus, see the section entitled “Where You Can Find More Information.”

Risks Relating to Arch’s Business

In addition to the risk factors described above relating to the combined company following completion of the merger, you should read and consider risk factors specific to Arch’s businesses that will also affect the combined company after the completion of the merger. These risks are described in Part I, Item 1A of Arch’s Annual Report on Form 10-K for the year ended December 31, 2023 and in Part II, Item 1A of Arch’s Quarterly Reports on Form 10-Q for the quarterly periods ended March 31, 2024, June 30, 2024 and September 30, 2024, and in other documents that are incorporated by reference herein. For the location of information incorporated by reference in this joint proxy statement/prospectus, see the section entitled “Where You Can Find More Information.”

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CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS

This joint proxy statement/prospectus, and the documents to which CONSOL and Arch refer you in this joint proxy statement/prospectus, as well as oral statements made or to be made by CONSOL and Arch relating to their respective special meetings of stockholders, include certain “forward-looking statements” within the meaning of Section 27A of the Securities Act and 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 joint proxy statement/prospectus, including those that address activities, events or developments that CONSOL or Arch expects, believes or anticipates will or may occur in the future, are forward-looking statements. Such forward-looking statements include, but are not limited to: statements about the benefits of the merger involving CONSOL and Arch, including future financial and operating results, CONSOL’s and Arch’s plans, objectives, expectations and intentions, the expected timing and likelihood of completion of the merger, and other statements that are not historical facts, including estimates of coal reserves, estimates of future production, assumptions regarding future coal pricing, planned delivery of coal to markets and the associated costs, future results of operations, projected cash flow and liquidity, business strategy and other plans and objectives for future operations. Words such as “anticipate,” “believe,” “budget,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “might,” “plan,” “potential,” “predict,” “seek,” “should,” “will,” “would,” “objective,” “projection,” “forecast,” “goal,” “guidance,” “forecast,” “outlook,” “target,” “commitment,” 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. No assurances can be given that the forward-looking statements contained in this communication will occur as projected and actual results may differ materially from those included in this joint proxy statement/prospectus. Forward-looking statements are based on current expectations, estimates and assumptions that involve a number of risks and uncertainties that could cause actual results to differ materially from those included in this joint proxy statement/prospectus. These risks and uncertainties include, without limitation:

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All of the forward-looking statements CONSOL and Arch make in or in connection with this joint proxy statement/prospectus are qualified by the information contained or incorporated by reference herein, including the information contained under this heading and the information detailed in CONSOL’s Annual Report on Form 10-K for the year ended December 31, 2023 and CONSOL’s Quarterly Report on Form 10-Q for the quarterly periods ended March 31, 2024, June 30, 2024 and September 30, 2024, Current Reports on Form 8-K and other filings CONSOL makes with the SEC, which are incorporated herein by reference, and in Arch’s Annual Report on Form 10-K for the year ended December 31, 2023 and Arch’s Quarterly Report on Form 10-Q for the quarterly period ended March 31, 2024, June 30, 2024 and September 30, 2024, Current Reports on Form 8-K and other filings Arch makes with the SEC, which are incorporated herein by reference. For additional information, see the sections entitled “Risk Factors” and “Where You Can Find More Information” beginning on pages 39 and 224, respectively.

Forward-looking statements are based on the estimates and opinions of management at the time the statements are made. Except to the extent required by applicable law, neither CONSOL nor Arch undertakes any obligation to publicly update or revise any forward-looking statement, whether as a result of new information, future events or otherwise. You are cautioned not to place undue reliance on these forward-looking statements that speak only as of the date hereof.

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INFORMATION ABOUT THE COMPANIES

CONSOL Energy Inc.

275 Technology Drive, Suite 101

Canonsburg, Pennsylvania 15317

Telephone: (724) 416-8300

CONSOL is a leading, low-cost producer and exporter of high-quality bituminous coal, focused on the extraction and preparation of coal in the Appalachian Basin due to its ability to efficiently produce and deliver large volumes of high-quality coal at competitive prices both domestically and abroad through its wholly-owned CONSOL Marine Terminal, the strategic location of its mines and the industry experience of its management team. CONSOL common stock is listed on the NYSE, trading under the symbol “CEIX.”

For additional information about CONSOL and its subsidiaries, see the documents incorporated by reference in this joint proxy statement/prospectus in the section entitled “Where You Can Find More Information” beginning on page 224.

Arch Resources, Inc.

One CityPlace Drive, Suite 300

St. Louis, Missouri 63141

Telephone: (314) 994-2700

Arch is one of the world’s largest coal producers and a premier producer of metallurgical coal. For the year ended December 31, 2023, Arch sold approximately 75 million tons of coal, including approximately 0.1 million tons of coal Arch purchased from third parties. Arch sells substantially all of its coal to steel mills, power plants and industrial facilities. At December 31, 2023, Arch operated seven active mines located in three of the major coal-producing regions of the United States. The locations of Arch’s mines and access to export facilities enable it to ship coal worldwide. Arch Class A common stock is listed on the NYSE, trading under the symbol “ARCH.”

For additional information about Arch and its subsidiaries, see the documents incorporated by reference in this joint proxy statement/prospectus in the section entitled “Where You Can Find More Information” beginning on page 224.

Mountain Range Merger Sub Inc.

c/o CONSOL Energy Inc.

275 Technology Drive, Suite 101

Canonsburg, Pennsylvania 15317

Phone: (724) 416-8300

Merger Sub is a wholly owned subsidiary of CONSOL. Upon the completion of the merger, Merger Sub will cease to exist. Merger Sub was incorporated in Delaware on August 16, 2024 for the sole purpose of effecting the merger.

The Combined Company

Upon the completion of the merger, CONSOL will be renamed “Core Natural Resources, Inc.” and its shares of common stock will trade on the NYSE under the ticker symbol “CNR.” The combined company will retain CONSOL’s current headquarters in Canonsburg, Pennsylvania. CONSOL and Arch have also agreed to certain governance matters relating to the board of directors and management of the combined company following the completion of the merger.

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SPECIAL MEETING OF CONSOL STOCKHOLDERS

Date, Time and Place

The CONSOL special meeting will be held virtually via live webcast on January 9, 2025, at 8:00 a.m. Eastern Time. Because the CONSOL special meeting is completely virtual and being conducted via live webcast, CONSOL stockholders will not be able to attend the CONSOL special meeting in person. CONSOL stockholders will be able to attend the CONSOL special meeting online and vote their shares and submit questions electronically during the meeting by visiting www.virtualshareholdermeeting.com/CEIX2025SM, which we refer to as the CONSOL special meeting website. CONSOL stockholders will need the 16-digit control number found on their proxy cards in order to access the CONSOL special meeting website.

Purpose of the CONSOL Special Meeting

The purpose of the CONSOL special meeting is to consider and vote on the following proposals:

CONSOL will transact no other business at the CONSOL special meeting, except such business as may properly be brought before the CONSOL special meeting by or at the direction of the CONSOL board in accordance with the CONSOL bylaws.

Recommendation of the CONSOL Board of Directors

The CONSOL board unanimously recommends that CONSOL stockholders vote “FOR” the CONSOL issuance proposal, “FOR” the CONSOL charter amendment proposal and “FOR” the CONSOL adjournment proposal.

For additional information on the recommendation of the CONSOL board, see the section entitled “The Merger—Recommendation of the CONSOL Board of Directors and Reasons for the Merger.”

Record Date and Outstanding Shares of CONSOL Common Stock

Only holders of record of issued and outstanding shares of CONSOL common stock as of the close of business on November 26, 2024, the record date for the CONSOL special meeting, are entitled to notice of, and to vote at, the CONSOL special meeting, whether via the CONSOL special meeting website or by proxy, or any adjournment or postponement of the CONSOL special meeting.

As of the close of business on the record date, there are expected to be approximately 29,394,466 shares of CONSOL common stock issued and outstanding and entitled to vote at the CONSOL special meeting. CONSOL stockholders may cast one vote for each share of CONSOL common stock held by them as of the close of business on the record date.

A complete list of CONSOL stockholders entitled to vote at the CONSOL special meeting will be available for inspection at CONSOL’s offices in Canonsburg, Pennsylvania during ordinary business hours for a period of no less than 10 days before the CONSOL special meeting. If you would like to examine the list of CONSOL stockholders, please contact the CONSOL Secretary at 275 Technology Drive, Suite 101, Canonsburg, Pennsylvania 15317.

Quorum; Abstentions, Broker Non-Votes and Failure to Vote

A quorum of CONSOL stockholders is necessary for CONSOL to conduct business at the CONSOL special meeting. The holders of a majority in voting power of the outstanding shares of CONSOL common stock entitled

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to vote at the CONSOL special meeting, present via the CONSOL special meeting website or by proxy, shall constitute a quorum for the transaction of business. If you submit a properly executed proxy card, even if you vote “against” the CONSOL proposals or “abstain” from voting on the CONSOL proposals, your shares of CONSOL common stock will be counted for purposes of calculating whether a quorum is present.

If you are a stockholder of record and you do not provide your proxy by signing and returning your proxy card or via the Internet, by telephone or vote at the CONSOL special meeting via the CONSOL special meeting website, your shares will not be voted with respect to a proposal at the CONSOL special meeting and will not be counted as present for purposes of determining whether a quorum exists.

Under the current NYSE rules, brokers, banks or other nominees do not have discretionary authority to vote on any of the CONSOL proposals at the CONSOL special meeting. Because all of the proposals for consideration at the CONSOL special meeting are “non-routine,” it is not expected that there will be any broker non-votes at the CONSOL special meeting. However, if there are any broker non-votes, they will have (1) the same effect as a vote “AGAINST” the CONSOL charter amendment proposal and (2) no effect on the outcome of the CONSOL issuance proposal or the CONSOL adjournment proposal.

Executed but unvoted proxies will be voted in accordance with the recommendation of the CONSOL board.

Required Vote

The votes required for each CONSOL proposal are as follows:

An abstention occurs when the beneficial owner of shares, or a broker, bank or other nominee holding shares for a beneficial owner, is present via the CONSOL special meeting website or by proxy at the CONSOL special meeting 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, bank or other nominee returns a valid proxy card without voting on such proposal because they did not receive voting instructions from the street name holder and do not have

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discretionary authority to vote the shares on a particular proposal. Shares represented by broker non-votes will not be voted on any proposal for which the broker, bank or other nominee has no discretionary authority to vote.

Under applicable rules, brokers or other nominees have discretionary voting power with respect to matters that are considered routine. Brokers will not be permitted to vote shares of CONSOL common stock at the CONSOL special meeting with respect to any of the CONSOL proposals at the CONSOL special meeting without receiving instructions from the beneficial owner of such shares.

The CONSOL issuance proposal, the CONSOL charter amendment proposal and the CONSOL adjournment proposal are described in the section entitled “CONSOL Proposals.”

Methods of Voting

CONSOL stockholders of record may vote by providing their proxies via the Internet by going to the web address provided on the enclosed proxy card and following the instructions for Internet voting, by phone using the toll-free phone number listed on the enclosed proxy card, or by completing, signing, dating and returning the enclosed proxy card in the postage-paid envelope provided.

CONSOL stockholders of record may vote their shares via the CONSOL special meeting website at the CONSOL special meeting or by submitting their proxies:

CONSOL stockholders who hold their shares in “street name” by a broker, bank or other nominee should refer to the voting instruction form or other information forwarded by their broker, bank or other nominee for instructions on how to vote their shares.

Voting via the CONSOL Special Meeting Website

Shares held directly in your name as stockholder of record may be voted at the CONSOL special meeting via the CONSOL special meeting website. If you choose to attend the CONSOL special meeting and vote your shares via the CONSOL special meeting website, you will need the 16-digit control number included on your proxy card. Even if you plan to attend the CONSOL special meeting, the CONSOL board recommends that you vote your shares in advance so that your vote will be counted if you later decide not to attend the CONSOL special meeting.

If you are a beneficial holder, you will need to obtain a control number from your broker, bank or other nominee holder of record giving you the right to vote the shares.

Questions About Voting

If you have any questions about how to vote or direct a vote in respect of your shares of CONSOL common stock, you may contact MacKenzie Partners, CONSOL’s proxy solicitor, at (800) 322-2885 (toll-free), or (212) 929-5500 (collect call).

Adjournment

If the CONSOL special meeting is adjourned, CONSOL stockholders who have already submitted their proxies will be able to revoke them at any time prior to their use. At any subsequent reconvening of the CONSOL special

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meeting, all proxies will be voted in the same manner as the manner in which such proxies would have been voted at the original convening of the CONSOL special meeting, except for any proxies that have been validly revoked or withdrawn prior to the subsequent meeting.

The merger agreement provides that CONSOL may adjourn, postpone or otherwise delay the CONSOL special meeting (1) if CONSOL believes in good faith that such adjournment is reasonably necessary to allow reasonable additional time to (A) solicit additional proxies necessary to obtain approval of the CONSOL issuance proposal or the CONSOL charter amendment proposal or (B) ensure that any legally required supplement or amendment to this joint proxy statement/prospectus is provided to the CONSOL stockholders; (2) if, as of the time for which the CONSOL special meeting is scheduled, there are insufficient shares of CONSOL common stock to constitute a quorum necessary to conduct the business of the CONSOL special meeting; (3) if and to the extent such postponement or adjournment of the CONSOL special meeting is required by an order issued by any court or other governmental entity of competent jurisdiction in connection with the merger agreement; or (4) if the Arch special meeting has been adjourned or postponed by Arch as described in the section entitled “The Merger Agreement—Special Meetings—Arch Special Meeting,” to the extent necessary to enable the CONSOL special meeting and the Arch special meeting to be held within a single period of 24 consecutive hours. However, unless otherwise agreed to by Arch and CONSOL, the CONSOL special meeting will not be adjourned or postponed to a date in the case of (1) or (2) above that is more than 20 business days after the date for which the meeting was previously scheduled, and will not be adjourned to a date on or after the date that is two business days prior to August 20, 2025 (or November 20, 2025, if extended pursuant to the merger agreement).

Revocability of Proxies

If you are a stockholder of record of CONSOL, whether you vote by phone, the Internet or mail, you can change or revoke your proxy before it is voted at the meeting in one of the following ways:

If you are a beneficial owner of CONSOL common stock as of the close of business on the record date, you must follow the instructions of your broker, bank or other nominee to revoke your voting instructions.

Proxy Solicitation Costs

The enclosed proxy card is being solicited by CONSOL and the CONSOL board. In addition to solicitation by mail, CONSOL’s directors, officers and employees may solicit proxies in person, by phone or by electronic means. These persons will not be specifically compensated for conducting such solicitation.

CONSOL has retained MacKenzie Partners to assist in the solicitation process. CONSOL will pay MacKenzie Partners a fee of approximately $20,000, as well as reasonable and customary documented expenses in an amount not to exceed $10,000. CONSOL also has agreed to indemnify MacKenzie Partners against various liabilities and expenses that relate to or arise out of its solicitation of proxies (subject to certain exceptions).

CONSOL will ask brokers, banks and other nominees to forward the proxy solicitation materials to the beneficial owners of shares of CONSOL common stock held of record by such nominee holders. CONSOL will reimburse these nominee holders for their customary clerical and mailing expenses incurred in forwarding the proxy solicitation materials to the beneficial owners.

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Appraisal Rights

Under Delaware law, CONSOL stockholders are not entitled to appraisal rights in connection with the issuance of shares of CONSOL common stock as contemplated by the merger agreement.

Other Information

The matters to be considered at the CONSOL special meeting are of great importance to the CONSOL stockholders. Accordingly, you are urged to read and carefully consider the information contained in or incorporated by reference into this joint proxy statement/prospectus and submit your proxy by phone or the Internet or complete, date, sign and promptly return the enclosed proxy card in the enclosed postage-paid envelope. If you submit your proxy by phone or the Internet, you do not need to return the enclosed proxy card.

Assistance

If you need assistance in completing your proxy card or have questions regarding the CONSOL special meeting, contact:

MacKenzie Partners, Inc.

1407 Broadway, 27th Floor, New York, NY 10018

Banks and Brokers Call Collect: (212) 929-5500

All Others Call Toll-Free: (800) 322-2885

Vote of CONSOL’s Directors and Executive Officers

As of November 26, 2024, the record date for the CONSOL special meeting, CONSOL directors and executive officers, and their affiliates, as a group, are expected to own and be entitled to vote approximately 598,020 shares of CONSOL common stock, or approximately 2.0% of the total outstanding shares of CONSOL common stock as of such date.

CONSOL currently expects that all of its directors and executive officers will vote their shares “FOR” the CONSOL issuance proposal, “FOR” the CONSOL charter amendment proposal and “FOR” the CONSOL adjournment proposal.

Attending the CONSOL Special Meeting Virtually

You are entitled to attend the CONSOL special meeting only if you are a stockholder of record of CONSOL at the close of business on the record date or you held your shares of CONSOL common stock beneficially in the name of a broker, bank or other nominee as of the record date, or if you hold a valid proxy for the CONSOL special meeting.

If you were a stockholder of record of CONSOL at the close of business on the record date and wish to attend the CONSOL special meeting, you will need the 16-digit control number located on your proxy card.

If a broker, bank or other nominee is the record owner of your shares of CONSOL common stock, you will need to obtain your control number and further instructions from your broker, bank or other nominee.

Results of the CONSOL Special Meeting

Within four business days following the CONSOL special meeting, CONSOL intends to file the final voting results with the SEC on a Current Report on Form 8-K. If the final voting results have not been certified within that four business-day-period, CONSOL will report the preliminary voting results on a Current Report on

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Form 8-K at that time and will file an amendment to the Current Report on Form 8-K to report the final voting results within four business days of the date that the final results are certified.

CONSOL STOCKHOLDERS SHOULD CAREFULLY READ THIS JOINT PROXY STATEMENT/PROSPECTUS IN ITS ENTIRETY FOR MORE DETAILED INFORMATION CONCERNING THE CONSOL PROPOSALS.

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CONSOL PROPOSALS

CONSOL Issuance Proposal

It is a condition to the completion of the merger that CONSOL stockholders approve the issuance of shares of CONSOL common stock in the merger. In the merger, each Arch stockholder will receive, for each eligible share of Arch common stock that is issued and outstanding as of immediately prior to the effective time of the merger, the merger consideration of 1.326 shares of CONSOL common stock, further described in the sections entitled “The Merger—Consideration to Arch Stockholders” and “The Merger Agreement—Effect of the Merger on Capital Stock; Merger Consideration.”

Under NYSE rules, a company is required to obtain stockholder approval prior to the issuance of shares of common stock if the number of shares of common stock to be issued is, or will be upon issuance, equal to or in excess of 20% of the number of shares of common stock outstanding before the issuance of the shares of common stock. If the merger is completed pursuant to the merger agreement, CONSOL expects to issue up to approximately 24,749,240 shares of CONSOL common stock in connection with the merger based on the number of shares of Arch common stock outstanding as of November 8, 2024 and the number of outstanding Arch equity awards currently estimated to be settled in CONSOL common stock in connection with the merger. Accordingly, the aggregate number of shares of CONSOL common stock that CONSOL will issue in the merger will exceed 20% of the shares of CONSOL common stock outstanding before such issuance, and for this reason, CONSOL is seeking the approval of CONSOL stockholders for the issuance of shares of CONSOL common stock pursuant to the merger agreement. In the event the CONSOL issuance proposal is not approved by CONSOL stockholders, the merger will not be completed.

In the event the CONSOL issuance proposal is approved by CONSOL stockholders, but the merger agreement is terminated (without the merger being completed) prior to the issuance of shares of CONSOL common stock pursuant to the merger agreement, CONSOL will not issue any shares of CONSOL common stock as a result of the approval of the CONSOL issuance proposal.

Approval of the CONSOL issuance proposal requires the affirmative vote of a majority of shares of CONSOL common stock present via the CONSOL special meeting website or by proxy at the CONSOL special meeting and entitled to vote on such proposal. Abstentions will have the same effect as a vote “AGAINST” the CONSOL issuance proposal, while broker non-votes or any failure by a CONSOL stockholder to vote (e.g., by not submitting a proxy and not voting at the CONSOL special meeting) will have no effect on the outcome of the CONSOL issuance proposal.

The CONSOL board unanimously recommends that you vote “FOR” the CONSOL issuance proposal.

CONSOL Charter Amendment Proposal

The CONSOL certificate of incorporation currently provides that the total number of shares of CONSOL common stock that CONSOL is authorized to issue is 62,500,000 shares. It is a condition to the completion of the merger that CONSOL stockholders adopt an amendment to the CONSOL certificate of incorporation to increase the number of authorized shares of CONSOL common stock from 62,500,000 shares to 125,000,000 shares.

The increased number of authorized shares of CONSOL common stock will ensure that CONSOL is able to issue the merger consideration in the merger. In addition, the CONSOL board believes that the increased number of authorized shares of CONSOL common stock contemplated by the proposed amendment is important to the combined company in order for additional shares to be available for issuance from time to time, without further action or authorization by the CONSOL stockholders (except as required by applicable law or the NYSE rules), if needed for such corporate purposes as may be determined by the CONSOL board. The additional 62,500,000 shares authorized would be a part of the existing class of CONSOL common stock and, if issued, would have the same rights and privileges as the shares of CONSOL common stock presently issued and outstanding.

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If the CONSOL stockholders approve the CONSOL charter amendment proposal and the merger is completed, CONSOL expects to file a Certificate of Amendment with the Secretary of State of the State of Delaware, in the form attached to this joint proxy statement/prospectus as Annex D, to increase the number of authorized shares of its capital and common stock. The Certificate of Amendment will only be effective if the merger is completed.

As of November 8, 2024, CONSOL had an aggregate of 29,394,466 shares of common stock issued and outstanding or reserved for issuance. Upon the completion of the merger, CONSOL anticipates issuing up to 24,749,240 shares of CONSOL common stock to Arch stockholders, resulting in 54,143,706 shares of CONSOL common stock issued and outstanding or reserved for issuance, which represents approximately 87% of CONSOL’s authorized shares of CONSOL common stock. The number of shares of CONSOL common stock that CONSOL anticipates issuing to Arch stockholders is based on the 18,664,328 shares of Arch Class A common stock outstanding, which includes outstanding awards of restricted Arch Class A common stock granted under Arch’s equity plans, and 257 shares of Arch Class B common stock outstanding, each as of November 8, 2024. In the event the CONSOL charter amendment proposal is not approved by CONSOL stockholders, the merger will not be completed.

Other than payment of the merger consideration and in connection with ordinary course equity compensation grants, the CONSOL board has no immediate plans to issue additional shares of common stock or securities that are convertible into common stock. However, the CONSOL board desires to have the shares available to provide flexibility for business and financial purposes and provide appropriate equity incentives for CONSOL’s employees, officers, directors, consultants and advisors. The additional shares may be used for various purposes without further stockholder approval. These purposes may include: (1) raising capital, if CONSOL has an appropriate opportunity, through offerings of common stock or securities that are convertible into or exchangeable for shares of common stock; (2) exchanges of common stock or securities that are convertible into or exchangeable for shares of common stock for other outstanding securities; (3) providing equity incentives to employees, officers, directors, consultants or advisors; (4) expanding CONSOL’s business through the acquisition of other businesses or assets; (5) stock splits, dividends, and similar transactions; and (6) other purposes.

The CONSOL charter amendment would also implement the change of CONSOL’s corporate name to “Core Natural Resources, Inc.”

Approval of the CONSOL charter amendment proposal requires the affirmative vote of a majority of the outstanding shares of CONSOL common stock entitled to vote on such proposal. Abstentions, broker non-votes, or any failure by a CONSOL stockholder to vote (e.g., by not submitting a proxy and not voting at the CONSOL special meeting) will have the same effect as a vote “AGAINST” the CONSOL charter amendment proposal.

The CONSOL board unanimously recommends that you vote “FOR” the CONSOL charter amendment proposal.

CONSOL Adjournment Proposal

CONSOL stockholders are being asked to approve a proposal that will grant the CONSOL board authority to adjourn the CONSOL special meeting, if necessary or appropriate, including to permit the further solicitation of additional votes or proxies if there are not sufficient votes cast at the CONSOL special meeting to approve the CONSOL issuance proposal or the CONSOL charter amendment proposal. Approval of this proposal is not a condition to the completion of the merger.

If the CONSOL adjournment proposal is approved, the CONSOL special meeting could be adjourned to any date. If the CONSOL special meeting is adjourned, CONSOL stockholders who have already submitted their proxies will be able to revoke them at any time prior to their use. If it is necessary to adjourn the CONSOL special meeting, no notice of the adjourned CONSOL special meeting is required to be given to CONSOL stockholders so long as (i) the place, the date and time of the adjourned CONSOL special meeting is announced at the CONSOL special meeting and (ii) the adjourned CONSOL special meeting occurs within 30 calendar days of the original date for the CONSOL special meeting and CONSOL does not fix a new record date for the adjourned meeting.

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Approval of the CONSOL adjournment proposal requires the affirmative vote of a majority of shares of CONSOL common stock present via the CONSOL special meeting website or by proxy at the CONSOL special meeting and entitled to vote on such proposal. Abstentions will have the same effect as a vote “AGAINST” the CONSOL adjournment proposal, while broker non-votes or any failure by a CONSOL stockholder to vote (e.g., by not submitting a proxy and not voting at the CONSOL special meeting) will have no effect on the outcome of the CONSOL adjournment proposal.

The CONSOL board unanimously recommends that you vote “FOR” the CONSOL adjournment proposal.

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SPECIAL MEETING OF ARCH STOCKHOLDERS

Date, Time and Place

The Arch special meeting will be held virtually via live webcast on January 9, 2025, at 8:00 a.m. Central Time. Because the Arch special meeting is completely virtual and being conducted via live webcast, Arch stockholders will not be able to attend the Arch special meeting in person. Arch stockholders will be able to attend the Arch special meeting online and vote their shares and submit questions electronically during the meeting by visiting www.virtualshareholdermeeting.com/ARCH2025SM, which we refer to as the Arch special meeting website. Arch stockholders will need the 16-digit control number found on their proxy cards in order to access the Arch special meeting website.

Purpose of the Arch Special Meeting

The purpose of the Arch special meeting is to consider and vote on the following proposals:

Arch will transact no other business at the Arch special meeting, except such business as may properly be brought before the Arch special meeting by or at the direction of the Arch board in accordance with the Arch bylaws.

Recommendation of the Arch Board of Directors

The Arch board unanimously recommends that Arch stockholders vote “FOR” the Arch merger proposal, “FOR” the Arch non-binding executive compensation advisory proposal and “FOR” the Arch adjournment proposal.

For additional information on the recommendation of the Arch board, see the section entitled “The Merger—Recommendation of the Arch Board of Directors and Reasons for the Merger.”

Record Date and Outstanding Shares of Arch Common Stock

Only holders of record of issued and outstanding shares of Arch common stock as of the close of business on November 26, 2024, the record date for the Arch special meeting, are entitled to notice of, and to vote at, the Arch special meeting, whether via the Arch special meeting website or by proxy, or any adjournment or postponement of the Arch special meeting.

As of the close of business on the record date, there are expected to be approximately 18,108,352 shares of Arch Class A common stock issued and outstanding and 257 shares of Arch Class B common stock issued and outstanding. Arch stockholders may cast one vote for each share of Arch common stock held by them as of the close of business on the record date.

A complete list of Arch stockholders entitled to vote at the Arch special meeting will be available for inspection at Arch’s offices in St. Louis, Missouri during ordinary business hours for a period of no less than 10 days before the Arch special meeting. If you would like to examine the list of Arch stockholders, please contact the Arch Secretary at One CityPlace Drive, Suite 300, St. Louis, Missouri 63141.

Quorum; Abstentions, Broker Non-Votes and Failure to Vote

A quorum of Arch stockholders is necessary for Arch to conduct business at the Arch special meeting. The holders of a majority of the outstanding shares of Arch common stock entitled to vote at the Arch special

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meeting, present via the Arch special meeting website or by proxy, shall constitute a quorum for the transaction of business. If you submit a properly executed proxy card, even if you vote “against” the Arch proposals or “abstain” from voting on the Arch proposals, your shares of Arch common stock will be counted for purposes of calculating whether a quorum is present.

If you are a stockholder of record and you do not provide your proxy by signing and returning your proxy card or via the Internet, by telephone or vote at the Arch special meeting via the Arch special meeting website, your shares will not be voted with respect to a proposal at the Arch special meeting and will not be counted as present for purposes of determining whether a quorum exists.

Under the current NYSE rules, brokers, banks or other nominees do not have discretionary authority to vote on any of the Arch proposals at the Arch special meeting. Because all of the proposals for consideration at the Arch special meeting are “non-routine,” it is not expected that there will be any broker non-votes at the Arch special meeting. However, if there are any broker non-votes, they will have (1) the same effect as a vote “AGAINST” the Arch merger proposal and the Arch adjournment proposal and (2) no effect on the outcome of the Arch non-binding executive compensation advisory proposal.

Executed but unvoted proxies will be voted in accordance with the recommendation of the Arch board.

Required Vote

The votes required for each Arch proposal are as follows:

An abstention occurs when the beneficial owner of shares, or a broker, bank or other nominee holding shares for a beneficial owner, is present via the Arch special meeting website or by proxy at the Arch special meeting, 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, bank or other nominee returns a valid proxy card without voting on such proposal because they did not receive voting instructions from the street name holder and do not have discretionary authority to vote the shares on a particular proposal. Shares represented by broker non-votes will not be voted on any proposal for which the broker, bank or other nominee has no discretionary authority to vote.

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Under applicable rules, brokers or other nominees have discretionary voting power with respect to matters that are considered routine. Brokers will not be permitted to vote shares of Arch common stock at the Arch special meeting with respect to any of the Arch proposals at the Arch special meeting without receiving instructions from the beneficial owner of such shares.

The Arch merger proposal, the Arch non-binding executive compensation advisory proposal and the Arch adjournment proposal are described in the section entitled “Arch Proposals.”

Methods of Voting

Arch stockholders of record may vote by providing their proxies via the Internet by going to the web address provided on the enclosed proxy card and following the instructions for Internet voting, by phone using the toll-free phone number listed on the enclosed proxy card, or by completing, signing, dating and returning the enclosed proxy card in the postage-paid envelope provided.

Arch stockholders of record may vote their shares via the Arch special meeting website at the Arch special meeting or by submitting their proxies:

Arch stockholders who hold their shares in “street name” by a broker, bank or other nominee should refer to the voting instruction form or other information forwarded by their broker, bank or other nominee for instructions on how to vote their shares.

Voting via the Arch Special Meeting Website

Shares held directly in your name as stockholder of record may be voted at the Arch special meeting via the Arch special meeting website. If you choose to attend the Arch special meeting and vote your shares via the Arch special meeting website, you will need the 16-digit control number included on your proxy card. Even if you plan to attend the Arch special meeting, the Arch board recommends that you vote your shares in advance so that your vote will be counted if you later decide not to attend the Arch special meeting.

If you are a beneficial holder, you will need to obtain a control number from your broker, bank or other nominee holder of record giving you the right to vote the shares.

Questions About Voting

If you have any questions about how to vote or direct a vote in respect of your shares of Arch common stock, you may contact Innisfree or King, Arch’s proxy solicitors, at (877) 717-3905 (toll-free), or (212) 750-5833 (collect call) or at (800) 848-3410 (toll free), or (212) 269-5550 (collect call), respectively.

Adjournment

If the Arch special meeting is adjourned, Arch stockholders who have already submitted their proxies will be able to revoke them at any time prior to their use. At any subsequent reconvening of the Arch special meeting, all proxies will be voted in the same manner as the manner in which such proxies would have been voted at the original convening of the Arch special meeting, except for any proxies that have been validly revoked or withdrawn prior to the subsequent meeting.

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The merger agreement provides that Arch may adjourn, postpone or otherwise delay the Arch special meeting (1) if Arch believes in good faith that such adjournment is reasonably necessary to allow reasonable additional time to (A) solicit additional proxies necessary to obtain approval of the Arch merger proposal or (B) ensure that any legally required supplement or amendment to this joint proxy statement/prospectus is provided to the Arch stockholders; (2) if, as of the time for which the Arch special meeting is scheduled, there are insufficient shares of Arch common stock to constitute a quorum necessary to conduct the business of the Arch special meeting; (3) if and to the extent such postponement or adjournment of the Arch special meeting is required by an order issued by any court or other governmental entity of competent jurisdiction in connection with the merger agreement; or (4) if the CONSOL special meeting has been adjourned or postponed by CONSOL as described in the section entitled “The Merger Agreement—Special Meetings—CONSOL Special Meeting,” to the extent necessary to enable the Arch special meeting and the CONSOL special meeting to be held within a single period of 24 consecutive hours. However, unless otherwise agreed to by CONSOL and Arch, the Arch special meeting will not be adjourned or postponed to a date in the case of (1) or (2) above that is more than 20 business days after the date for which the meeting was previously scheduled, and will not be adjourned to a date on or after the date that is two business days prior to August 20, 2025 (or November 20, 2025, if extended pursuant to the merger agreement).

Revocability of Proxies

If you are a stockholder of record of Arch, whether you vote by phone, the Internet or mail, you can change or revoke your proxy before it is voted at the meeting in one of the following ways:

If you are a beneficial owner of Arch common stock as of the close of business on the record date, you must follow the instructions of your broker, bank or other nominee to revoke your voting instructions.

Proxy Solicitation Costs

The enclosed proxy card is being solicited by Arch and the Arch board. In addition to solicitation by mail, Arch’s directors, officers and employees may solicit proxies in person, by phone or by electronic means. These persons will not be specifically compensated for conducting such solicitation.

Arch has retained Innisfree and King to assist in the solicitation process. Arch has paid Innisfree a fee of $17,500 and will pay Innisfree a fee of $17,500, which may be supplemented by additional appropriate fees for certain additional services, as well as reasonable and customary documented expenses. Arch has paid King a fee of $12,500 and will pay King a fee of $12,500, which may be supplemented by additional reasonable and documented fees for additional services at King’s reasonable and customary rates as mutually agreed to in writing, as well as reasonable and customary documented expenses. Arch also has agreed to indemnify each of Innisfree and King against various liabilities and expenses that relate to or arise out of its solicitation of proxies (subject to certain exceptions).

Arch will ask brokers, banks and other nominees to forward the proxy solicitation materials to the beneficial owners of shares of Arch common stock held of record by such nominee holders. Arch will reimburse these nominee holders for their customary clerical and mailing expenses incurred in forwarding the proxy solicitation materials to the beneficial owners.

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Appraisal Rights

Under Delaware law, holders of Arch Class A common stock are not entitled to appraisal rights in connection with the issuance of shares of CONSOL common stock as contemplated by the merger agreement.

However, holders of the 257 shares of Arch Class B common stock currently issued and outstanding are entitled to appraisal rights under Section 262 of the DGCL. For more information, see the section entitled “Appraisal Rights” on page 213.

Other Information

The matters to be considered at the Arch special meeting are of great importance to the Arch stockholders. Accordingly, you are urged to read and carefully consider the information contained in or incorporated by reference into this joint proxy statement/prospectus and submit your proxy by phone or the Internet or complete, date, sign and promptly return the enclosed proxy card in the enclosed postage-paid envelope. If you submit your proxy by phone or the Internet, you do not need to return the enclosed proxy card.

Assistance

If you need assistance in completing your proxy card or have questions regarding the Arch special meeting, contact:

Innisfree M&A Incorporated

501 Madison Avenue, 20th Floor, New York, NY 10022

Banks and Brokers Call Collect: (212) 750-5833

All Others Call Toll-Free: (877) 717-3905

or

D.F. King & Co., Inc.

48 Wall Street, 22nd Floor, New York, NY 10005

Banks and Brokers Call Collect: (212) 269-5550

All Others Call Toll-Free: (800) 848-3410

Vote of Arch’s Directors and Executive Officers

As of November 26, 2024, the record date for the Arch special meeting, Arch directors and executive officers, and their affiliates, as a group, are expected to own and be entitled to vote approximately 420,195 shares of Arch common stock, or approximately 2.3% of the total outstanding shares of Arch common stock as of such date.

Arch currently expects that all of its directors and executive officers will vote their shares “FOR” the Arch merger proposal, “FOR” the Arch non-binding executive compensation advisory proposal and “FOR” the Arch adjournment proposal.

Attending the Arch Special Meeting Virtually

You are entitled to attend the Arch special meeting only if you are a stockholder of record of Arch at the close of business on the record date or you held your shares of Arch common stock beneficially in the name of a broker, bank or other nominee as of the record date, or if you hold a valid proxy for the Arch special meeting.

If you were a stockholder of record of Arch at the close of business on the record date and wish to attend the Arch special meeting, you will need the 16-digit control number located on your proxy card.

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If a broker, bank or other nominee is the record owner of your shares of Arch common stock, you will need to obtain your control number and further instructions from your broker, bank or other nominee.

Results of the Arch Special Meeting

Within four business days following the Arch special meeting, Arch intends to file the final voting results with the SEC on a Current Report on Form 8-K. If the final voting results have not been certified within that four-business-day period, Arch will report the preliminary voting results on a Current Report on Form 8-K at that time and will file an amendment to the Current Report on Form 8-K to report the final voting results within four business days of the date that the final results are certified.

ARCH STOCKHOLDERS SHOULD CAREFULLY READ THIS JOINT PROXY STATEMENT/PROSPECTUS IN ITS ENTIRETY FOR MORE DETAILED INFORMATION CONCERNING THE ARCH PROPOSALS.

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ARCH PROPOSALS

Arch Merger Proposal

It is a condition to the completion of the merger that Arch stockholders approve the Arch merger proposal. In the merger, each Arch stockholder will receive, for each eligible share of Arch common stock that is issued and outstanding as of immediately prior to the effective time of the merger, the merger consideration of 1.326 shares of CONSOL common stock, as further described in the sections entitled “The Merger—Consideration to Arch Stockholders” and “The Merger Agreement—Effect of the Merger on Capital Stock; Merger Consideration.”

Pursuant to Section 251 of the DGCL and in order to fulfill a condition to the consummation of the merger contained in the merger agreement, Arch stockholders are being asked to adopt the merger agreement as it relates to the merger.

The Arch board has unanimously determined that the merger agreement and the transactions contemplated by the merger agreement, including the merger, are fair to, and in the best interests of, Arch stockholders and has unanimously approved and declared advisable the merger agreement and the transactions contemplated by the merger agreement, including the merger. For a summary of the merger agreement and the merger, including the background of the merger, Arch’s reasons for the merger, the opinion of Arch’s financial advisor and related matters, see the sections entitled “The Merger” and “The Merger Agreement.”

Approval of the Arch merger proposal requires the affirmative vote of a majority of the outstanding shares of Arch common stock entitled to vote on such proposal. Abstentions, broker non-votes, or any failure by an Arch stockholder to vote (e.g., by not submitting a proxy and not voting at the Arch special meeting) will have the same effect as a vote “AGAINST” the Arch merger proposal.

The Arch board unanimously recommends that you vote “FOR” the Arch merger proposal.

Arch Non-Binding Executive Compensation Advisory Proposal

As required by Section 14A of the Exchange Act and the applicable SEC rules issued thereunder, which were enacted pursuant to the Dodd-Frank Wall Street Reform and Consumer Protection Act, Arch is required to provide its stockholders the opportunity to vote to approve, on a non-binding, advisory basis, certain compensation that may be paid or become payable to Arch’s named executive officers that is based on or otherwise relates to the merger, as described in the section entitled “The Merger—Interests of Arch Directors and Executive Officers in the Merger—Quantification of Potential Payments and Benefits to Arch’s Named Executive Officers—Golden Parachute Compensation.” Accordingly, Arch stockholders are being provided the opportunity to cast an advisory vote on such payments. As an advisory vote, this proposal is not binding upon Arch or the Arch board, or upon CONSOL or the CONSOL board, and approval of this proposal is not a condition to the completion of the merger and is a vote separate and apart from the Arch merger proposal and the Arch adjournment proposal. Accordingly, you may vote to approve the Arch merger proposal and the Arch adjournment proposal and vote not to approve the Arch non-binding executive compensation advisory proposal and vice-versa. Because the merger-related executive compensation to be paid in connection with the merger is based on the terms of the merger agreement as well as the contractual arrangements with Arch’s named executive officers, such compensation will be payable, regardless of the outcome of this advisory vote, if the merger is completed (subject only to the contractual conditions applicable thereto). However, Arch seeks the support of its stockholders and believes that stockholder support is appropriate as the executive compensation programs are designed to incentivize executives to successfully execute a transaction such as that contemplated by the merger from its early stages until consummation. Accordingly, Arch stockholders are being asked to vote on the following resolution:

RESOLVED, that the stockholders of Arch Resources, Inc. approve, on an advisory, non-binding basis, certain compensation that may be paid or become payable to the named executive officers of Arch Resources, Inc. that is

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based on or otherwise relates to the merger, as disclosed pursuant to Item 402(t) of Regulation S-K under the heading “The Merger—Interests of Arch Directors and Executive Officers in the Merger—Quantification of Potential Payments and Benefits to Arch’s Named Executive Officers—Golden Parachute Compensation.”

Approval of the Arch non-binding executive compensation advisory proposal requires the affirmative vote of a majority of the shares of Arch common stock voting thereon at the Arch special meeting. Abstentions, broker non-votes, or any failure by an Arch stockholder to vote (e.g., by not submitting a proxy and not voting at the Arch special meeting) will have no effect on the outcome of the Arch non-binding executive compensation advisory proposal.

The Arch board unanimously recommends that you vote “FOR” the Arch non-binding executive compensation advisory proposal.

Arch Adjournment Proposal

Arch stockholders are being asked to approve a proposal that will grant the Arch board authority to adjourn the Arch special meeting, if necessary or appropriate, including to permit the further solicitation of additional votes or proxies if there are not sufficient votes cast at the Arch special meeting to approve the Arch merger proposal.

If the Arch adjournment proposal is approved, the Arch special meeting could be adjourned to any date. If the Arch special meeting is adjourned, Arch stockholders who have already submitted their proxies will be able to revoke them at any time prior to their use. If it is necessary to adjourn the Arch special meeting, no notice of the adjourned Arch special meeting is required to be given to Arch stockholders so long as (i) the place, date and time of the adjourned Arch special meeting is announced at the Arch special meeting and (ii) the adjourned Arch special meeting occurs within 30 days of the original date for the Arch special meeting and Arch does not fix a new record date for the adjourned meeting.

Approval of the Arch adjournment proposal requires the affirmative vote of a majority of the shares of Arch common stock present via the Arch special meeting website or by proxy at the Arch special meeting, whether or not a quorum is present. Abstentions and broker non-votes will have the same effect as a vote “AGAINST” the Arch adjournment proposal, while any failure by an Arch stockholder to vote (e.g., by not submitting a proxy and not voting at the Arch special meeting) will have no effect on the outcome of the Arch adjournment proposal. Approval of this proposal is not a condition to the completion of the merger.

The Arch board unanimously recommends that you vote “FOR” the Arch adjournment proposal.

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THE MERGER

This discussion of the merger is qualified in its entirety by reference to the merger agreement, which is attached to this joint proxy statement/prospectus as Annex A and incorporated by reference herein in its entirety. You should read the entire merger agreement carefully as it is the legal document that governs the merger.

Transaction Structure

At the effective time of the merger, Merger Sub will merge with and into Arch. As a result of the merger, the separate corporate existence of Merger Sub will cease, and Arch will continue as the surviving corporation in the merger and as a wholly owned subsidiary of CONSOL.

Consideration to Arch Stockholders

As a result of the merger, each eligible share of Arch common stock issued and outstanding immediately prior to the effective time of the merger will be converted into the right to receive 1.326 shares of CONSOL common stock, which we refer to as the merger consideration.

Arch stockholders will not be entitled to receive any fractional shares of CONSOL common stock in the merger, and no Arch stockholders will be entitled to dividends, voting rights or any other rights in respect of any fractional shares of CONSOL common stock. Arch stockholders that would have otherwise been entitled to receive a fractional share of CONSOL common stock will instead be entitled to receive, in lieu of such fractional shares of CONSOL common stock, cash (without interest) in an amount equal to the product of (1) the aggregate net cash proceeds as determined by the next sentence and (2) a fraction, the numerator of which is such fractional part of a share of CONSOL common stock, and the denominator of which is the number of shares of CONSOL common stock constituting a portion of the exchange fund as represents the aggregate of all fractional entitlements of all Arch stockholders. As promptly as possible following the effective time of the merger, the exchange agent will sell at then-prevailing prices on the NYSE such number of shares of CONSOL common stock constituting a portion of the exchange fund as represents the aggregate of all fractional entitlements of all Arch stockholders, with the cash proceeds (net of all commissions, transfer taxes and other out-of-pocket costs and expenses of the exchange agent incurred in connection with such sales) of such sales to be used by the exchange agent to fund the foregoing payments in lieu of fractional shares.

Background of the Merger

The terms of the merger are the result of arms’-length negotiations between Arch and CONSOL. The following is a summary of the events leading up to the parties’ agreement to merge and the key meetings, negotiations, discussions and actions between Arch and CONSOL and their respective advisors that preceded the public announcement of the proposed merger.

The management and board of directors of each of Arch and CONSOL regularly review and assess their respective company’s performance, strategy, financial position, leverage, opportunities and risks in light of current business and economic conditions and overall industry trends and developments. These reviews have included, at various times and at the direction of the board of directors of each of Arch and CONSOL, the evaluation of various potential alternatives available to Arch and CONSOL, respectively, including mergers, acquisitions, divestitures, joint ventures and other strategic opportunities as well as review of the then-current business plan and the considerations associated with maintaining the status quo and continuing to execute on the then-current business plan. As part of these reviews, the board of directors of each of Arch and CONSOL receives periodic updates from management and certain of their advisors regarding the general landscape of mergers and acquisitions, potential acquirers and merger and acquisition candidates.

With respect to Arch, as demand in the United States domestic thermal market has declined due to, among other matters, competition from natural gas and subsidized alternative energy sources, Arch has sought to enhance

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stockholder value by pursuing strategic opportunities that would be likely to increase its operating cash flow, reduce the impact of fluctuations in the metallurgical coal market on its cash flows, expand its footprint in the seaborne market where Arch believes the demand for energy-dense coal appears more durable and optimize its capital structure, thereby strengthening its competitive position in the market as a large-scale, low-cost provider of energy, and enhance its overall competitiveness of the business by unlocking optimization opportunities and reducing overhead costs. In addition, the Arch board believed that any significant strategic combination would need to be with a partner that had a similar operating philosophy and focus on enhancement of stockholder value.

As part of the Arch board’s ordinary review of strategic opportunities, Mr. Paul A. Lang, the Chief Executive Officer of Arch, had a discussion with the Arch board at a regularly scheduled board meeting on October 29, 2022, regarding the retention of outside advisors to consider potential strategic alternatives that may be available to Arch to enhance long-term stockholder value. Following this discussion, and as part of this exercise, representatives of Arch had several conversations and meetings with various banks and consultants in late 2022 and early 2023.

On January 25 and 26, 2023, Mr. Lang, Mr. Matthew C. Giljum, Chief Financial Officer of Arch, Mr. Deck S. Slone, Senior Vice President, Strategy, of Arch, and Mr. Renato Paladino, Vice President of Business Development of Arch, met with Perella Weinberg Partners LP (“PWP”) to review potential strategic alternatives for Arch. Following this meeting with PWP and other potential advisors, Messrs. Lang and Slone recommended that the Arch board engage PWP to assist Arch with a potential review of strategic alternatives. The Arch board ultimately retained PWP based on management’s recommendation, PWP’s reputation and experience in the coal industry and PWP’s experience advising companies in mergers and acquisitions. Through this work with PWP and in consultation with the Arch board, several initial strategic alternatives were developed and identified for potential further exploration, which alternatives were shared in a preliminary fashion at Arch’s regularly scheduled board meeting on February 9, 2023. At this meeting, Mr. Lang was directed by the Arch board to continue to explore these alternatives.

During February 2023, Mr. Lang was also approached by a strategic company in the energy industry (“Company A”) regarding a possible strategic transaction with Arch. In connection with these discussions, Company A provided some high-level background information and a summary of their operations. After review by Arch management and several discussions between Mr. Lang and members of the Arch board, members of the Arch board advised Mr. Lang not to continue pursuit of this potential strategic transaction because such members believed that it would be difficult to combine the two companies and achieve certain synergies and that Company A had certain operational risks that made the financial benefits of such strategic combination uncertain.

After several informal discussions regarding industry dynamics, on February 28, 2023, at the BMO Metals and Mining Conference in Fort Lauderdale, Florida, and again on March 7, 2023, Mr. Lang met with the Chief Executive Officer of a strategic company in the coal industry (“Company B”) to discuss a potential business transaction between Arch, Company B and another strategic company in the coal industry (“Company C”). Mr. Lang informed Mr. John W. Eaves, the former Executive Chairman of the Arch board, of the conversations and Mr. Eaves directed Mr. Lang to continue to explore the potential strategic transaction.

On March 28, 2023, Messrs. Lang and Slone, along with representatives of Arch’s legal counsel, Latham & Watkins LLP (“Latham”), met at the offices of a potential financial advisor to Company B to discuss a potential joint acquisition of Company C by Arch and Company B. Through the end of March 2023 and into April 2023, a series of calls were held with Company B, PWP and other outside advisors about the potential transaction.

On May 12, 2023, the Arch board held a regularly scheduled meeting attended by members of Arch management and representatives of Latham. The topics included the general state of the market for acquisitions and divestitures and consolidation in the coal industry and potential strategic alternatives for Arch’s consideration at such time. During the meeting, representatives of Arch management updated the Arch board on the discussions with Company A and Company B since the last meeting. The Arch board agreed with the prior assessment that a

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strategic transaction with Company A was not likely to be in the best interests of Arch and its stockholders given the potential for other potential strategic alternatives. Also during the meeting, the Arch board considered a potential strategic transaction between Arch and Company B and Company C, as well as a potential merger of Arch with a strategic company in the coal industry (“Company D”) who Mr. Eaves had several informal discussions with from 2018 through 2020. Following discussion and deliberation, the Arch board determined that it would be in the best interests of Arch and its stockholders to pursue a strategic combination with Company D. Accordingly, the Arch board directed Mr. Lang to submit a non-binding letter of interest for a business combination with Company D. Following this meeting, at the direction of the Arch board, Mr. Lang informed Company A that the Arch board had determined not to continue discussing a potential strategic transaction with Company A.

Mr. Lang worked with PWP and Latham to draft a non-binding letter of interest expressing Arch’s interest in pursuing a business combination between Arch and Company D. On May 31, 2023, Messrs. Lang and Slone attended an in-person meeting with the Chief Executive Officer and Chief Financial Officer of Company D, where Mr. Lang presented the non-binding letter of interest. Representatives of Company D expressed that they did not think that a market-based merger of equals with no premium would be of interest to the board of directors of Company D.

On June 1, 2023, Mr. Eaves spoke with the chairman of Company D to further discuss the proposal that Arch had provided to Company D. Subsequently, on June 13, 2023, Company D sent a letter to Arch indicating that Company D was not interested in pursuing a transaction at that time. After a follow-up discussion between Mr. Eaves and the chairman of Company D on June 21, 2023, no further discussions were had between Arch and Company D.

On July 20, 2023, the Arch board held a regularly scheduled meeting with Arch management. The meeting included Arch’s annual review of company strategy and a presentation by Arch management and PWP related to various organic and inorganic growth alternatives and an update on the discussions with Company D. At this meeting, the Arch board directed Arch management to continue to explore several alternatives, including a possible merger of equals with CONSOL.

On August 7, 2023, a representative of PWP reached out to Mr. Brock to schedule a meeting between Mr. Brock and Mr. Lang.

Subsequently, on September 12, 2023, at an in-person meeting in Canonsburg, Pennsylvania, Mr. Lang and James A. Brock, the Chief Executive Officer of CONSOL, discussed a possible merger of equals transaction between Arch and CONSOL at an exchange ratio commensurate with the companies’ trading prices, with no premium. Following those discussions, Arch and CONSOL entered into a mutual non-disclosure agreement on September 14, 2023 (the “NDA”), which contained a customary mutual standstill provision that terminates upon either party entering into a definitive agreement with a third party involving more than 50% of such party’s equity securities or assets. Also following these discussions, Mr. Brock updated Mr. William P. Powell, who was then the Chairman of the CONSOL board, on the discussion with Mr. Lang.

On September 18, 2023, representatives of Moelis & Company LLC (“Moelis”) met with representatives of CONSOL management to discuss preliminary considerations with respect to the potential transaction with Arch, and the potential engagement of Moelis to advise CONSOL. Pursuant to a letter agreement, dated November 16, 2023, between CONSOL and Moelis, Moelis was engaged as financial advisor to CONSOL in connection with the proposed merger. The CONSOL board retained Moelis based on management’s recommendation, Moelis’ reputation and experience in the coal industry and Moelis’ experience advising companies in mergers and acquisitions.

On September 22, 2023, at a board meeting of the National Mining Association, Messrs. Lang and Brock had a brief discussion regarding a possible merger, with a focus on deal logistics and starting the process of evaluating the business combination. Messrs. Lang and Brock did not discuss any material terms of such potential merger.

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On October 4, 2023, Messrs. Lang and Brock met in person at the Washington County, Pennsylvania airport to discuss a possible transaction between Arch and CONSOL, including potential synergies and post-closing governance matters for the combined company. Following that discussion, on October 6, 2023, representatives of Arch and PWP met with representatives of CONSOL and Moelis, at the Spirit of St. Louis airport to discuss the potential transaction. Mr. Brock updated Mr. Powell, with respect to these discussions.

On October 19, 2023, the Arch board held a regularly scheduled meeting attended by members of Arch management. Mr. Lang provided an update as to the status of the discussions with CONSOL and was directed by the Arch board to continue discussions.

On October 24, 2023, the CONSOL board held a special meeting attended by representatives of CONSOL management. Mr. Brock and Miteshkumar B. Thakkar, CONSOL’s President and Chief Financial Officer, presented to the CONSOL board regarding the potential transaction with Arch and provided an update as to the discussions to date with Arch and its representatives. During the meeting, among other things, the CONSOL board discussed the potential transaction as compared to a range of different strategic alternatives potentially available to CONSOL, including maintaining the status quo. After discussion, the CONSOL board directed Messrs. Brock and Thakkar to continue such discussions.

On November 2, 2023, Messrs. Lang, Eaves, Brock and Powell met in Westchester, New York to discuss the potential transaction, including post-closing governance arrangements.

Between November 6, 2023, and November 16, 2023, representatives of Arch, CONSOL, PWP and Moelis participated in multiple due diligence calls, which included discussions of potential synergies, pricing and macroeconomic assumptions to be utilized in preparing the respective five-year forecasts for Arch and CONSOL.

On November 17, 2023, the Arch board convened a special meeting, which members of Arch management and representatives of Latham and PWP attended. PWP provided an update on the possible transaction with CONSOL, including the ongoing synergy analysis, preparation of comparative financial models for the two companies and due diligence conducted to date. The PWP presentation included an exchange ratio analysis based on the then-current and historic stock prices of the two companies. Arch management provided an update on due diligence performed to date. Representatives from Latham advised the Arch board of their fiduciary duties with respect to a potential merger transaction and discussed certain legal due diligence matters. After detailed discussion regarding the transaction, including the common pricing assumptions that would be reflected in the financial models, the Arch board directed Arch management to continue to progress the transaction workstreams in advance of the next meeting of the Arch board.

Arch, CONSOL and their advisors continued to progress due diligence over the following weeks, including entering into a clean team addendum to the NDA on November 25, 2023, to allow for sharing of certain information between Arch’s and CONSOL’s clean team members. In addition, on November 27, 2023, Arch and CONSOL exchanged forecast models for their respective businesses, and representatives of Arch, CONSOL, PWP and Moelis held several calls on November 28, 2023, and November 29, 2023, to answer questions regarding the models. Also during this period, through December 2023, there were several due diligence calls held between the parties.

On November 28, 2023, Mr. Lang met with the Chief Executive Officer of Company B in St. Louis, Missouri regarding prior discussions of a possible transaction with Company C. During the meeting, the Chief Executive Officer of Company B raised the potential of a merger of Company B with Arch (with or without a subsequent potential transaction involving Company C).

On November 29, 2023, Messrs. Lang and Brock met in person at the Washington County, Pennsylvania airport to discuss the status of the ongoing workstreams relating to the transaction, including due diligence.

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On November 30, 2023, the CONSOL board convened a special meeting, which representatives of CONSOL management and Moelis attended. During the meeting, representatives of Moelis presented to the CONSOL board regarding the management forecast models prepared by CONSOL management and Arch management, respectively. The CONSOL board discussed with CONSOL management and representatives of Moelis the status of discussions regarding the potential merger with Arch and considerations with respect to the potential transaction, including progress on due diligence, the potential transaction structure, the clean team addendum to the NDA, transaction documentation and remaining high priority due diligence items.

On December 1, 2023, the Arch board convened a special meeting, which members of Arch management and representatives of Latham and PWP attended. During the meeting, representatives of PWP provided an updated exchange ratio analysis based on the then-current and historic stock prices of the two companies, and presented preliminary financial analyses with respect to a potential transaction with CONSOL. Representatives of Arch management presented the financial models for the two companies and answered questions from the Arch directors with respect to pricing assumptions and industry outlook for the thermal and metallurgical coal markets. Representatives from Latham presented on litigation risks in merger transactions and provided an update on due diligence. Following discussion, the Arch board directed Arch’s management and advisors to continue progressing a potential transaction and to continue the due diligence evaluation of CONSOL.

On December 2, 2023, representatives of Latham shared with representatives of Wachtell Lipton Rosen & Katz (“Wachtell Lipton”), outside counsel to CONSOL, a draft merger agreement, which provided that Arch would be the acquiring entity in a merger of equals with CONSOL.

Between December 4, 2023, and December 8, 2023, representatives from Arch, PWP, CONSOL and Moelis held additional meetings focused on the status of the thermal coal market, financial due diligence and a pro forma combined capital structure for the two companies.

On December 5, 2023, Messrs. Lang, Eaves, Brock and Powell met in person at the Westchester, New York airport to discuss the status of the discussions between Arch and CONSOL.

On December 6, 2023, representatives of Wachtell Lipton shared with representatives of Latham a draft merger agreement, which provided that CONSOL would be the acquiring entity in a merger of equals with Arch. Neither Latham nor Wachtell Lipton commented on the other party’s draft merger agreement.

On December 8, 2023, the CONSOL board convened a special meeting, which representatives of CONSOL management and Moelis attended. During the meeting, representatives of Moelis presented to the CONSOL board regarding preliminary financial analysis for a potential merger between CONSOL and Arch. The CONSOL board discussed with CONSOL management and representatives of Moelis the status of discussions regarding the potential merger with Arch and considerations with respect to the potential transaction.

On December 11, 2023, the Arch board convened a regularly scheduled meeting, which members of Arch management and representatives of Latham and PWP attended. During the meeting, representatives of Latham provided an update on due diligence. Following deliberation, the Arch board directed Mr. Lang to express to CONSOL the concerns held by the Arch board regarding certain potential indemnification obligations of CONSOL relating to alleged pension plan liabilities, and the need for Arch to further diligence this risk before transaction negotiations could progress. Mr. Lang also updated the Arch board on the discussions with the Chief Executive Officer of Company B and was directed to continue exploring a potential transaction with Company B.

On December 11, 2023, after the meeting of the Arch board, Mr. Lang called Mr. Brock and conveyed this message.

On December 12, 2023, Arch engaged Vedder Price P.C. (“Vedder Price”) and Dinsmore & Shohl LLP (“Dinsmore”) to assist with the ongoing due diligence of CONSOL’s potential pension plan indemnification liabilities given their significant experience in this area and expertise in the coal industry. From December 12,

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2023, to January 3, 2024, members of Arch management and representatives of Latham, Vedder Price and Dinsmore continued to evaluate the magnitude of CONSOL’s potential pension plan indemnification liability.

On December 12, 2023, the CONSOL board convened a special meeting, which representatives of CONSOL management and Moelis attended. During the meeting, CONSOL management updated the CONSOL board on the status of discussions with Arch. After discussion, and noting the significant time and resources that CONSOL had already expended in satisfying Arch’s due diligence requests, the CONSOL board authorized Mr. Brock to terminate discussions with Arch regarding the potential transaction if Arch was unable to reach a conclusion as to its comfort with respect to CONSOL’s potential pension plan indemnification liabilities in a reasonable timeframe.

On December 12, 2023, Mr. Lang communicated to Mr. Brock that Arch was not willing to move forward with a potential transaction between Arch and CONSOL without greater clarity on CONSOL’s potential pension plan indemnification liabilities. Messrs. Lang and Brock determined to officially terminate the discussions between Arch and CONSOL.

On December 13, 2023, each of Arch and CONSOL closed its virtual data room to the other party and the parties ceased discussions regarding a potential strategic combination.

On January 3, 2024, members of Arch management and representatives from Latham, Vedder Price and Dinsmore held a telephonic meeting to discuss the evaluation of CONSOL’s potential pension plan indemnification liability that Arch and its advisors had independently conducted (without any additional information from or contact with CONSOL) following the meeting of the Arch board on December 11, 2023. Latham discussed the fiduciary duties of the board in connection with evaluating a potential transaction involving a material risk identified in the due diligence process. The discussion highlighted the significant perceived risks to Arch stockholders raised by CONSOL’s exposure to pension plan liabilities and the limited comfort that Arch and its advisors had with the level of information that was available to them at the time.

On January 4, 2024, Mr. Lang provided Arch legal counsels’ findings, along with the detailed underlying analysis, to the Arch board along with his recommendation that Arch stop any further work on the potential merger with CONSOL.

On January 24, 2024, Mr. Lang and the Chief Executive Officer of Company B met in St. Louis, Missouri to continue discussions regarding a potential transaction. Following this meeting, Mr. Lang and the Chief Executive Officer of Company B had several additional phone calls and meetings to discuss a potential transaction.

Between January 2024 and March 2024, Messrs. Lang and Brock had several informal discussions regarding industry conditions. During this time, Arch continued informal discussions with other potential merger partners, including entering into a mutual non-disclosure agreement with Company B on February 2, 2024, which contained a customary mutual standstill provision that terminates upon either party entering into a definitive agreement with a third party involving more than 50% of such party’s equity securities or assets.

On February 21, 2024, the Arch board held a regularly scheduled meeting attended by members of Arch management. Mr. Lang updated the Arch board on the continuing discussions with Company B and was directed to continue exploring a potential transaction with Company B.

On March 4, 2024, CNX Resources Corporation (“CNX”), CONSOL’s former parent company, entered into a settlement agreement with respect to certain potential pension plan liabilities of CNX, and subsequently sought indemnification for the full amount of the settlement payment, plus other costs and expenses, including legal expenses, interest and punitive damages, from CONSOL pursuant to the agreements entered into in connection with the separation of CNX and CONSOL.

On March 12, 2024, Mr. Brock contacted Mr. Lang to inform Mr. Lang of the pension plan settlement. Messrs. Brock and Lang discussed potentially reengaging in discussions regarding a possible transaction between Arch

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and CONSOL in light of the settlement. Each of Mr. Lang and Mr. Brock indicated to the other that he would update their respective board of directors on the discussion.

On March 14, 2024, the CONSOL board held a regularly scheduled meeting attended by representatives of CONSOL management. Mr. Brock updated the CONSOL board on his outreach to Mr. Lang. After discussion, the CONSOL board authorized CONSOL management to re-commence the exploration of a potential transaction with Arch.

On March 18 and 19, 2024, Messrs. Lang and Brock had discussions regarding management changes announced at Arch and the pension plan settlement.

On March 26, 2024, a large container vessel lost power and struck one of the main support piers of the Francis Scott Key Bridge, effectively blocking shipping access to Baltimore Harbor. This incident disrupted operations for companies in a wide array of industries and geographies, including Arch and CONSOL.

Messrs. Lang, Eaves, Brock and Mr. Richard A. Navarre, a director of Arch, met in person at the Pittsburgh, Pennsylvania airport on April 3, 2024, to discuss a potential transaction and introduce Mr. Navarre as Arch’s incoming Chairman of the Board given Mr. Eaves’ upcoming retirement.

On April 12, 2024, Messrs. Lang, Eaves, Navarre, Brock, Thakkar and John T. Mills, a director of CONSOL, met to discuss post-transaction governance and introduce Mr. Mills as CONSOL’s new lead outside director following the death of Mr. Powell. The representatives of Arch and CONSOL again discussed the concept of a merger of equals with no premium to either party, along with various social and governance issues, including that the surviving entity in the merger of equals would be the one with the larger market capitalization at the time of signing and the combined company would have a name other than Arch or CONSOL following the closing of the merger.

On April 18, 2024, representatives of CONSOL and Arch met to discuss the macroeconomic environment and the forecast models for their respective businesses.

On April 19, 2024, Mr. Lang updated Mr. Brock on Arch’s announced executive management changes and potential implications of the executive management changes for the combined company if a transaction were to be further pursued.

On April 23, 2024, the Arch board convened a special meeting, which members of Arch management attended. During the meeting, Mr. Lang provided an update on a potential transaction with CONSOL, including an update on the post-closing governance terms most recently discussed between the parties.

On April 24, 2024, Messrs. Lang, Brock, Giljum, Thakkar, Slone, and Paladino, Ms. Martha A. Wiegand, General Counsel of CONSOL, and Ms. Rosemary L. Klein, General Counsel of Arch, had a telephonic meeting to discuss due diligence matters.

On May 7, 2024, the Arch board held a regularly scheduled meeting with members of Arch management, and Mr. Lang provided the Arch board with an update on the status of merger discussions with CONSOL, including with respect to post-closing governance items, as well as the continuing discussions with Company B.

On May 8, 2024, Messrs. Lang and Brock discussed the status of due diligence. On May 16, 2024, Messrs. Lang and Brock, together with other members of Arch management, met to discuss the potential transaction.

On May 12, 2024, Arch and CONSOL exchanged updated forecast models for their respective businesses.

On May 15, 2024, representatives of CONSOL and Arch met to discuss potential synergies in connection with the merger.

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On May 22, 2024, the CONSOL board held a special meeting attended by representatives of CONSOL management and Moelis. During the meeting, Messrs. Brock and Thakkar updated the CONSOL board on the status of discussions with Arch and the evaluation of a potential merger transaction. Also during the meeting, representatives of Moelis presented to the CONSOL board regarding a market trading and sector update and the updated management forecast models prepared by CONSOL management and Arch management, respectively.

Between May 23, 2024 and May 30, 2024, Messrs. Lang and Brock held multiple discussions regarding the status of due diligence.

On May 24, 2024, the Arch board convened a special meeting, which members of Arch management and representatives of Latham and PWP attended by video conference. During the meeting, Mr. Lang, other members of Arch management and representatives of Latham and PWP provided an update on a potential transaction with CONSOL.

On May 30, 2024, the CONSOL board convened a special meeting, which representatives of CONSOL management attended. During the meeting, Messrs. Brock and Thakkar updated the CONSOL board on the status of discussions with Arch and the evaluation of a potential merger transaction, and the CONSOL board discussed due diligence matters and focus areas as well as other potential strategic alternatives available to CONSOL.

On June 2, 2024, Messrs. Lang, Brock, Thakkar and Mr. John T. Drexler, President of Arch, briefly discussed ongoing due diligence while attending the Global Coal Forum outside of Bristol, Tennessee.

On June 11, 2024, Messrs. Navarre and Brock discussed the status of the potential transaction and positions on certain social issues.

On June 12, 2024, and June 19, 2024, Messrs. Lang and Brock discussed the status of the due diligence process and made arrangements for site visits to key mines. The parties held several site visits on June 6, 2024, June 20, 2024, and June 22, 2024.

On June 18, 2024, the CONSOL board held a special meeting attended by representatives of CONSOL management. During the meeting, Mr. Brock updated the CONSOL board on the status of discussions with Arch and the evaluation of a potential merger transaction. The CONSOL board agreed that Mr. Brock would provide the CONSOL board with a further update following the completion of the scheduled mine tours and, at that point, the CONSOL board would consider whether to authorize further exploration of the potential merger transaction.

On June 23 and 24, 2024, Messrs. Lang and Navarre had in-person meetings in Texas with the Chief Executive Officer and Chairman of the board of directors of Company B to discuss a possible transaction. Among other topics related to a possible transaction, the representatives of Arch and Company B discussed the effect of certain overlaps in the companies’ operations on the regulatory approval process and closing certainty and timing. The parties raised several social issues and acknowledged that these matters would be further discussed if discussions regarding a potential transaction progressed.

On June 25, 2024, the CONSOL board held a special meeting attended by members of CONSOL management. During the meeting, Mr. Brock provided an update to the CONSOL board regarding the site visits conducted at the Arch mines. After discussion, the CONSOL board authorized CONSOL management to continue its exploration of a potential transaction.

On July 8, 2024, each of Arch and CONSOL reopened its respective virtual data room to the other party, and there was an update discussion between Messrs. Brock and Navarre. On July 11, 2024, following a discussion between Messrs. Lang and Brock on July 10, 2024, regarding the possible transaction, each of Arch and CONSOL made certain information available to the other party’s clean team members.

On July 9, 2024, the CONSOL board held a special meeting attended by representatives of CONSOL management. During the meeting, Messrs. Brock and Thakkar and Ms. Wiegand provided an update to the

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CONSOL board regarding the status of the exploration of the transaction with Arch, including due diligence matters and the draft merger agreement, and a potential transaction negotiation / due diligence timeline.

On July 15, 2024, representatives of Arch, CONSOL, PWP and Moelis discussed the status of a possible transaction between Arch and CONSOL, including with respect to remaining due diligence.

On July 17 and 18, 2024, the Arch board held a regularly scheduled meeting in Gillette, Wyoming, which members of Arch management attended. During the meeting, Mr. Lang and representatives of PWP provided an update on the possible transaction with CONSOL by video conference. Mr. Lang also provided an update to the Arch board on the status of discussions with Company B and was directed to provide an analysis of the possible combination with Company B as compared to a possible transaction with CONSOL.

On July 18, 2024, representatives of Wachtell Lipton shared with Latham a draft merger agreement, which, among other matters, provided that CONSOL would be the parent corporation in a merger of equals with Arch. Additionally, the draft merger agreement reflected, among other provisions, reciprocal representations, warranties and interim operating covenants, a “force the vote” provision requiring each of Arch and CONSOL to hold their respective stockholder meetings relating to the merger regardless of a change in the respective board of directors’ recommendation, a termination fee of $100 million payable by each party in certain situations and an expense reimbursement payable by each party in certain situations.

On July 25, 2024, Messrs. Navarre and Brock had an update conversation on the status of Arch and CONSOL’s due diligence.

On July 27, 2024, representatives of Latham shared a revised draft of the merger agreement with representatives of Wachtell Lipton, which similarly provided that CONSOL would be the parent corporation in a merger of equals with Arch. The revised merger agreement included a termination fee based on each party’s respective enterprise value, proposed an end date of nine months, with an automatic three-month extension in certain circumstances, after which either party could terminate the merger agreement if the transaction had not been consummated by such time, and allowed for Arch to continue paying a fixed quarterly dividend to its stockholders through the closing.

Between July 27, 2024, and August 7, 2024, representatives of Arch and Company B, along with representatives of Arch’s financial advisors, participated in due diligence calls and engaged in discussions with respect to a potential transaction between Arch and Company B. In addition, on July 30, 2024, Arch and Company B exchanged forecast models for their respective businesses. The parties discussed the models on a call on August 1, 2024.

On August 2, 2024, the Arch board convened a special meeting, which members of Arch management and representatives of Latham, PWP and antitrust counsel to Arch, Gibson, Dunn & Crutcher LLP (“Gibson Dunn”), attended. During the meeting, Mr. Lang provided an update on the remaining open items in the transaction between Arch and CONSOL, including with respect to post-closing governance of the combined company, and the status of transaction discussions between Arch and Company B. Representatives of Arch and Latham provided a summary of the draft merger agreement with CONSOL and an update on due diligence, including with respect to potential pension plan indemnification liabilities and litigation matters. PWP presented a preliminary financial analysis for a possible transaction with Company B, and Gibson Dunn presented an overview of antitrust considerations with respect to a possible transaction with Company B. Following this discussion, the Arch board directed members of Arch management to prioritize the merger with CONSOL over a potential transaction with Company B. Mr. Lang later informed the Chief Executive Officer of Company B that Arch was prioritizing another transaction.

On August 5, 2024, representatives of Wachtell Lipton shared a revised draft of the merger agreement with representatives of Latham. The revised merger agreement included a termination fee for both parties based on the

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combined company’s equity value implied by the merger, proposed an end date of 12 months, with an automatic three-month extension, and provided that CONSOL would also have the flexibility to declare and pay quarterly dividends to its stockholders prior to the closing.

On August 9, 2024, Company B shared a draft merger agreement with Arch and Latham. The agreement contemplated that Arch would negotiate a divestiture of certain assets ahead of signing in order to address the regulatory concerns previously discussed between the parties. The agreement was otherwise silent on a number of points, including the proposed exchange ratio and post-closing governance matters.

On August 9, 2024, the CONSOL board held a special meeting attended by representatives of CONSOL management, Moelis and Wachtell Lipton. During the meeting, representatives of Moelis presented to the CONSOL board regarding a market trading and sector update. In addition, during the meeting, Mr. Brock updated the CONSOL board regarding the status of discussions with Arch and the evaluation of a potential transaction.

On August 10, 2024, Arch and CONSOL exchanged updated forecast models for their respective businesses.

On August 12, 2024, the Arch board convened a special meeting, which members of Arch management, representatives of Latham, PWP and Gibson Dunn attended. Representatives of Arch, Latham, PWP and Gibson Dunn provided a summary of the key provisions and issues in the draft merger agreement from Company B, including the contemplated divestiture of certain of Arch’s assets prior to signing the merger agreement. Following further discussion with representatives of Latham, PWP and Gibson Dunn, the Arch board and members of Arch management determined that the possible transaction with CONSOL was more economically attractive and posed significantly less risk and uncertainty than a possible transaction with Company B. Given these factors, the Arch board and members of Arch management further determined that it would not be in the best interests of Arch and its stockholders to risk losing a possible transaction with CONSOL in order to further pursue a transaction with Company B.

On August 12, 2024, representatives of Latham shared a revised draft of the merger agreement with representatives of Wachtell Lipton. The revised merger agreement included a termination fee based on each party’s respective enterprise value and allowed for the parties to declare and pay quarterly dividends in an amount proportionate to the exchange ratio.

On August 13, 2024, the CONSOL board held a special meeting attended by representatives of CONSOL management, Moelis, Wachtell Lipton and McGuireWoods LLP, counsel to CONSOL (“McGuireWoods”). During the meeting, representatives of Moelis presented to the CONSOL board regarding the updated management forecast models prepared by CONSOL management and Arch management, respectively, and preliminary financial analysis for a potential merger between CONSOL and Arch. In addition, during the meeting, representatives of Wachtell Lipton presented to the CONSOL board regarding the required regulatory and stockholder approvals required in connection with the potential transaction and the potential timeline to signing of the merger agreement and closing of the transaction.

On August 14, 2024, representatives of Wachtell Lipton shared a revised draft of the merger agreement with representatives of Latham. The revised merger agreement included a termination fee for both parties based on Arch’s equity value, allowed for the parties to declare and pay quarterly dividends (subject to an aggregate cap) and provided for a one-time dividend to be declared by CONSOL at the announcement of the merger in an amount proportionate to Arch’s second quarter dividend.

On August 14, 2024, representatives of CONSOL, Arch, Moelis and PWP met to discuss potential synergies in connection with the merger.

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On August 15, 2024, the Arch board convened a special meeting, which members of Arch management and representatives of Latham and PWP attended. Representatives of Arch provided an update on the status of the draft merger agreement and due diligence with CONSOL. Representatives of PWP then presented preliminary financial analyses with respect to a possible transaction with CONSOL which had been updated to reflect revised forecasted coal prices due to market conditions, and discussed the impact of market conditions on Arch’s stock price and the proposed exchange ratio in a possible transaction with CONSOL. Following discussion, the Arch board directed Mr. Lang and PWP to seek an increased exchange ratio in light of market conditions. The Arch board also directed Latham to share a revised draft of the merger agreement with representatives of Wachtell Lipton.

On August 15, 2024, the CONSOL board held a special meeting attended by representatives of CONSOL management, Moelis, Wachtell Lipton and McGuireWoods. During the meeting, representatives of management and McGuireWoods presented to the CONSOL board regarding the due diligence conducted with respect to the investigation of the potential transaction.

On August 16, 2024, representatives of Latham shared a revised draft of the merger agreement with representatives of Wachtell Lipton, which included a termination fee based on each party’s respective equity value.

Also on August 16, 2024, Messrs. Lang, Brock and Thakkar met to discuss and agree upon the pro forma headquarters, name and management team of the combined company as well as other governance matters. In addition, between August 16, 2024, and August 18, 2024, Messrs. Lang, Brock and Navarre, as well as representatives of PWP and Moelis, had several conversations regarding the proposed exchange ratio to be used in the possible transaction between Arch and CONSOL. During such discussions, Messrs. Lang and Navarre and representatives of PWP each proposed using an exchange ratio based on a trailing volume-weighted-average price of the companies rather than a current trading price.

On August 18, 2024, the CONSOL board convened a special meeting, which representatives of CONSOL management attended. During the meeting, Mr. Brock updated the CONSOL board regarding the exchange ratio proposed by representatives of Arch and PWP. After discussion, the CONSOL board instructed Mr. Brock to reject the exchange ratio proposed by representatives of Arch. Following the meeting, Mr. Brock indicated to Mr. Lang that CONSOL would not accept Arch’s proposed exchange ratio.

On August 18, 2024, the Arch board convened a special meeting, which members of Arch management and representatives of Latham and PWP attended. During the meeting, Mr. Lang provided an update on discussions with CONSOL regarding a possible transaction, including that after further discussion between the CONSOL board and its advisors, CONSOL had rejected Arch’s proposed method of calculating the exchange ratio. Mr. Lang provided an overview of the rationale for, and risks associated with, a possible transaction with CONSOL at the proposed exchange ratio, including considering Arch management’s view of Arch’s future performance, the synergies that the transaction could create and the lower execution risk offered by the CONSOL transaction. Representatives of PWP then presented preliminary financial analyses with respect to a possible transaction with CONSOL at the proposed exchange ratio, and representatives of Latham then provided a summary of the draft merger agreement with CONSOL. Following discussion, the Arch board approved members of Arch management and representatives of Latham and PWP continuing to negotiate a possible transaction with CONSOL based on an exchange ratio calculated based on current market prices.

On August 19, 2024, Mr. Lang indicated to Mr. Brock that Arch was willing to agree to an exchange ratio that was based on current market prices rather than a trailing volume-weighted-average price. Messrs. Lang and Brock agreed that the exchange ratio would be calculated after market closing on August 19, 2024 based on the closing prices as of such date in an “at-the-market” deal with no premium.

On August 19, 2024, following such agreement, representatives of Wachtell Lipton shared a revised draft of the merger agreement with representatives of Latham, which provided for a termination fee for both parties based on

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Arch’s equity value and an equal per-share cap on quarterly dividends for each of Arch and CONSOL. On August 20, 2024, representatives of Latham shared a revised draft of the merger agreement with representatives of Wachtell Lipton, and following further discussion between Messrs. Lang and Brock, Arch and CONSOL agreed on the remaining open points in the merger agreement.

On August 20, 2024, the CONSOL board convened a special meeting, which representatives of CONSOL management, Moelis, Wachtell Lipton and McGuireWoods attended. During the meeting, representatives of Wachtell Lipton provided an overview of the CONSOL directors’ fiduciary duties with respect to a possible transaction and the terms of the proposed merger agreement with Arch and other definitive transaction documentation. Representatives of Moelis then reviewed with the CONSOL board its financial analyses of the exchange ratio and delivered to the CONSOL board an oral opinion, which was confirmed by delivery of a written opinion, dated August 20, 2024, addressed to the CONSOL board to the effect that, as of the date of the opinion and based upon and subject to the assumptions made, procedures followed, matters considered and other limitations set forth in the opinion, the exchange ratio in the merger was fair, from a financial point of view, to CONSOL. Following further discussion, the CONSOL board unanimously determined that the merger agreement and the transactions contemplated by the merger agreement, including the CONSOL stock issuance pursuant to the merger agreement and the CONSOL charter amendment, were fair to, and in the best interests of, CONSOL and the holders of CONSOL common stock, approved and declared advisable the merger agreement and the transactions contemplated by the merger agreement, including the CONSOL stock issuance pursuant to the merger agreement and the CONSOL charter amendment, and resolved to recommend that the holders of CONSOL common stock approve the CONSOL stock issuance pursuant to the merger agreement and the CONSOL charter amendment.

On August 20, 2024, the Arch board convened a special meeting, which members of Arch management and representatives of Latham, PWP and Gibson Dunn attended. During the meeting, representatives of Latham provided an overview of the Arch directors’ fiduciary duties with respect to a possible transaction. Representatives of Arch and Latham then provided a summary of the proposed merger agreement with CONSOL, including the provisions restricting the parties and their representatives from soliciting competing offers, the provisions requiring the parties to use reasonable best efforts and take certain actions with respect to obtaining regulatory approval for the merger and the provisions restricting each party’s conduct of business between the execution of the merger agreement and the closing without the other party’s consent. Representatives of PWP then presented financial analyses with respect to a possible transaction with CONSOL at the proposed exchange ratio, and the Arch board asked questions regarding the financial analyses. Following such discussion, PWP delivered to the Arch board its opinion that, as of the date of such opinion and based upon and subject to the various limitations, qualifications and assumptions and other matters set forth therein, the merger consideration to be received by holders of Arch common stock (other than CONSOL and its affiliates and holders of excluded shares) in the merger pursuant to the merger agreement was fair, from a financial point of view, to such holders. Following further discussion, the Arch board unanimously determined that the merger agreement and the transactions contemplated by the merger agreement, including the merger, were fair to, and in the best interests of, Arch and the holders of Arch common stock, approved and declared advisable the merger agreement and the transactions contemplated by the merger agreement, including the merger, and resolved to recommend that the holders of Arch common stock adopt the merger agreement.

Following the meetings of the Arch and CONSOL boards of directors on August 20, 2024, representatives of Latham and Wachtell Lipton finalized the merger agreement and other transaction documents, and the merger agreement and other transaction documents were executed by the parties. Before the opening of stock market trading on August 21, 2024, Arch and CONSOL issued a joint press release announcing the transaction.

Recommendation of the CONSOL Board of Directors and Reasons for the Merger

By a unanimous vote at a meeting held on August 20, 2024, the CONSOL board determined that the merger agreement and the transactions contemplated by the merger agreement, including the issuance of shares of

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CONSOL common stock in connection with the merger and the amendment to the CONSOL certificate of incorporation to increase CONSOL’s authorized shares of common stock, were fair to, and in the best interests of, CONSOL and its stockholders, and approved and declared advisable the merger agreement and the transactions contemplated by the merger agreement, including the issuance of shares of CONSOL common stock in connection with the merger and the amendment of the CONSOL certificate of incorporation, and resolved to recommend that the CONSOL stockholders approve the issuance of shares of CONSOL common stock in connection with the merger and the amendment of the CONSOL certificate of incorporation.

The CONSOL board unanimously recommends that CONSOL stockholders vote “FOR” the CONSOL issuance proposal, “FOR” the CONSOL charter amendment proposal and “FOR” the CONSOL adjournment proposal.

In the course of reaching its determinations and recommendations, the CONSOL board met multiple times and reviewed and discussed a significant amount of information and consulted with members of CONSOL’s senior management and CONSOL’s outside legal and financial advisors. The following are some of the significant factors that supported the CONSOL board’s determinations and recommendation (which are presented below in no particular order and are not exhaustive):

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The CONSOL board also considered and balanced against the potentially positive factors with a number of uncertainties, risks and other countervailing factors in its deliberations concerning the merger and the merger agreement, including the following (which are presented below in no particular order and are not exhaustive):

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The CONSOL board considered all of these factors as a whole and unanimously determined that the merger agreement and the transactions contemplated thereby, including the issuance of shares of CONSOL common stock in connection with the merger and the amendment to the CONSOL certificate of incorporation to increase CONSOL’s authorized shares of common stock, were fair to, and in the best interests of, CONSOL and its stockholders. The foregoing discussion of the information and factors considered by the CONSOL board in reaching its conclusions and recommendation includes the principal factors considered by the CONSOL board, but is not intended to be exhaustive and may not include all of the factors considered by the CONSOL board. In view of the wide variety of factors considered by the CONSOL board in connection with its evaluation of the merger and the complexity of these matters, the CONSOL board did not consider it practical to, nor did it attempt to, quantify, rank or otherwise assign relative or specific weights to the specific factors that it considered in reaching its decision. Rather, the CONSOL board viewed its decisions as being based on the totality of the factors and information it considered. In considering the factors described above and any other factors, each individual member of the CONSOL board applied his or her own personal business judgment to the process and may have viewed factors differently or given different weight or merit to different factors.

In considering the recommendation of the CONSOL board that the CONSOL stockholders vote to approve the CONSOL issuance proposal and the CONSOL charter amendment proposal, CONSOL stockholders should be aware that the directors and executive officers of CONSOL have certain interests in the merger that may be different from, or in addition to, the interests of CONSOL stockholders generally. The CONSOL board was aware of these interests and considered them when approving the merger agreement and recommending that CONSOL stockholders vote to approve the CONSOL issuance proposal, which are described in the section entitled “—Interests of CONSOL Directors and Executive Officers in the Merger.”

The foregoing discussion of the information and factors considered by the CONSOL board is forward-looking in nature and should be read in light of the factors described in the section entitled “Cautionary Statement Regarding Forward-Looking Statements.”

Opinion of Moelis & Company LLC, CONSOL’s Financial Advisor

At the meeting of the CONSOL board on August 20, 2024 to evaluate and approve the merger agreement and the transactions contemplated by the merger agreement, Moelis delivered an oral opinion, which was confirmed by delivery of a written opinion, dated August 20, 2024, addressed to the CONSOL board to the effect that, as of the date of its opinion and based upon and subject to the assumptions made, procedures followed, matters considered and other limitations set forth in the opinion, the exchange ratio in the merger was fair, from a financial point of view, to CONSOL.

The full text of Moelis’ written opinion dated August 20, 2024, which sets forth the assumptions made, procedures followed, matters considered and limitations on the review undertaken in connection with the opinion, is attached as Annex B to this joint proxy statement/prospectus and is incorporated herein by reference. Moelis’ opinion was provided for the use and benefit of the CONSOL board (solely in its capacity as such) in its evaluation of the merger. Moelis’ opinion is limited solely to the fairness from a financial point of view of the exchange ratio in the merger to CONSOL, and does not address CONSOL’s underlying business decision to effect the merger or the relative merits of the merger as compared to any alternative business strategies or transactions that might be available to CONSOL. Moelis’ opinion does not constitute a recommendation as to how any holder of securities of CONSOL or Arch should vote or act with respect to the merger or any other matter.

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In arriving at its opinion, Moelis, among other things:

In connection with its analysis and opinion, Moelis relied on the information supplied to, discussed with or reviewed by it being complete and accurate in all material respects. Moelis did not independently verify any such information (or assume any responsibility for the independent verification of any such information). Moelis also relied on the representation of CONSOL management that they were not aware of any facts or circumstances that would make any such information inaccurate or misleading. Moelis relied upon, without independent verification, the assessment of CONSOL and its legal, tax, regulatory and accounting advisors with respect to legal, tax, regulatory and accounting matters. With respect to the financial forecasts and other information relating to CONSOL, Arch, the projected synergies and the NOLs referred to above, Moelis assumed, at the direction of the CONSOL board, that they were reasonably prepared on a basis reflecting the best then available estimates and judgments of the management of CONSOL or Arch, as the case may be, as to the future performance of CONSOL and Arch, such projected synergies (including the amount, timing and achievability thereof) and the NOLs (including the timing and utilization thereof). Moelis also assumed, at the direction of the

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CONSOL board, that the future financial results and the projected synergies and the NOLs would be achieved at the times and in the amounts projected. In addition, Moelis relied on the assessments of the managements of CONSOL and Arch as to CONSOL’s ability to retain key employees of Arch and to integrate the businesses of CONSOL and Arch. Moelis did not express any views as to the reasonableness of any financial forecasts or the projected synergies or the NOLs or the assumptions on which they were based. In addition, Moelis did not make any independent evaluation or appraisal of any of the assets or liabilities (contingent, derivative, off-balance-sheet, or otherwise) of CONSOL or Arch, nor was it furnished with any such evaluation or appraisal.

Moelis’ opinion did not address CONSOL’s underlying business decision to effect the merger or the relative merits of the merger as compared to any alternative business strategies or transactions that might be available to CONSOL. Moelis’ opinion did not address any legal, regulatory, tax or accounting matters. Moelis was not asked to, and Moelis did not, offer any opinion as to any terms of the merger agreement or any aspect or implication of the merger, except for the fairness of the exchange ratio from a financial point of view to CONSOL. Moelis’ opinion relates to the relative values of CONSOL and Arch. Moelis expressed no opinion as to what the value of CONSOL common stock actually would be when issued pursuant to the merger or the prices at which CONSOL common stock or Arch common stock may trade at any time. Moelis did not express any opinion as to fair value, viability or the solvency of CONSOL or Arch following the closing of the merger. In rendering its opinion, Moelis assumed that the final executed form of the merger agreement would not differ in any material respect from the version that Moelis reviewed, that the merger would be consummated in accordance with its terms without any waiver or modification that could be material to its analysis, that the representations and warranties of each party set forth in the merger agreement were accurate and correct, and that the parties to the merger agreement would comply with all the material terms of the merger agreement. Moelis assumed that all governmental, regulatory or other consents or approvals necessary for the completion of the merger would be obtained, except to the extent that could not be material to its analysis. In addition, representatives of CONSOL advised Moelis, and Moelis assumed, that the merger would qualify as a tax free reorganization for federal income tax purposes. Moelis was not authorized to solicit and have not solicited indications of interest in a possible transaction with CONSOL from any party.

Moelis’ opinion was necessarily based on economic, monetary, market and other conditions as in effect on, and the information made available to Moelis as of, the date of its opinion, and Moelis assumed no responsibility to update its opinion for developments after the date of its opinion. As the CONSOL board was aware, the credit, financial and stock markets had been experiencing unusual volatility and Moelis expressed no opinion or view as to any potential effects of such volatility on CONSOL, Arch or the merger.

Moelis’ opinion did not address the fairness of the merger or any aspect or implication thereof to, or any other consideration of or relating to, the holders of any class of securities, creditors or other constituencies of CONSOL, other than the fairness of the exchange ratio from a financial point of view to CONSOL. In addition, Moelis did not express any opinion as to the fairness of the amount or nature of any compensation to be received by any officers, directors or employees of any parties to the merger, or any class of such persons, relative to the exchange ratio or otherwise. Moelis’ opinion was approved by a Moelis fairness opinion committee.

Summary of Financial Analyses

The following is a summary of the material financial analyses presented by Moelis to the CONSOL board at its meeting held on August 20, 2024, in connection with delivery of its opinion. This summary describes the material analyses underlying Moelis’ opinion but does not purport to be a complete description of the analyses performed by Moelis in connection with its opinion.

Some of the summaries of financial analyses below include information presented in tabular format. In order to fully understand Moelis’ analyses, the tables must be read together with the text of each summary. The tables alone do not constitute a complete description of the analyses. Considering the data described below without considering the full narrative description of the financial analyses, including the methodologies and assumptions underlying the analyses, could create a misleading or incomplete view of Moelis’ analyses.

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For the purposes of Moelis’ analyses:

Discounted Cash Flow Analysis—Standalone

Utilizing the August 2024 CONSOL Projections and the August 2024 Arch Projections, Moelis performed a discounted cash flow (“DCF”) analysis of each of CONSOL and Arch, respectively, to calculate the present value of the estimated future unlevered free cash flows projected by their respective managements to be generated by CONSOL and Arch and the present value of the estimated terminal value of each of CONSOL and Arch.

CONSOL

Moelis calculated CONSOL’s unlevered free cash flow as LL-Adjusted EBITDA (i) less SBC expense, (ii) less cash taxes, (iii) less capital expenditures, (iv) plus decreases in net working capital, (v) less increases in net working capital and (vi) less greenhouse gas reduction initiatives.

Moelis utilized a range of discount rates of 9.25% to 12.00% based on an estimated range of CONSOL’s weighted average cost of capital (the “WACC”). The estimated WACC range reflected a derived cost of equity range using the capital asset pricing model (“CAPM”) and a size premium. Moelis used the foregoing range of discount rates to calculate estimated present values as of June 30, 2024 of (i) estimated unlevered free cash flows of CONSOL for the second half of the calendar year ending December 31, 2024 through the end of the calendar year ending December 31, 2028 (in each case, discounted using a mid-year discounting convention) and (ii) estimated terminal values derived by applying a range of selected terminal multiples of 4.00x to 5.00x to CONSOL’s terminal year LL-Adjusted EBITDA (which was equal to LL-Adjusted EBITDA for the calendar year ending December 31, 2028).

For purposes of selecting the reference range to apply to CONSOL’s estimated terminal year LL-Adjusted EBITDA, Moelis noted that (i) the selected reference range was primarily informed by the current and recent trading multiples for CONSOL and the Selected Companies (as defined below), with greater emphasis placed on the trading multiples for CONSOL over the last one-year time period, (ii) longer-dated historical trading multiples were considered but relied less upon due to the differences between the current and projected versus historical coal market dynamics, (iii) the similarities between the more normalized recent coal pricing

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environments and the coal pricing assumptions underpinning the financial projections received from CONSOL management and (iv) the implied trading multiple discount of CONSOL relative to that of Arch over the last one- and two-year time periods. Based on the foregoing analysis and its professional judgment and experience, Moelis selected a terminal multiple range of 4.00x to 5.00x CONSOL’s estimated terminal year LL-Adjusted EBITDA. Moelis then applied such multiple range to CONSOL’s estimated terminal year LL-Adjusted EBITDA based on the August 2024 CONSOL Projections to calculate the estimated terminal values.

In calculating the implied equity value of CONSOL, Moelis removed the income statement and free cash flow impacts of the legacy liabilities for CONSOL and treated these liabilities as net debt adjustments.

The standalone implied range of equity values for CONSOL and implied range of share prices for the CONSOL common stock derived from the DCF analysis for CONSOL are presented below:

Arch

Moelis calculated Arch’s unlevered free cash flow as LL-Adjusted EBITDA (i) less SBC expense, (ii) less cash taxes, (iii) less capital expenditures, (iv) plus decreases in net working capital, (v) less increases in net working capital, (vi) plus loss from equity investments, (vii) less purchases of investments and advances to affiliates, (viii) less additions to prepaid royalties and (ix) less other cash flow items.

Moelis utilized a range of discount rates of 9.25% to 12.00% based on an estimated range of Arch’s WACC. The estimated WACC range reflected a derived cost of equity range using CAPM and a size premium. Moelis used the foregoing range of discount rates to calculate estimated present values as of June 30, 2024 of (i) estimated unlevered free cash flows of Arch for the second half of the calendar year ending December 31, 2024 through the end of the calendar year ending December 31, 2028 (in each case, discounted using a mid-year discounting convention) and (ii) estimated terminal values derived by applying a range of selected terminal multiples of 4.50x to 5.50x to Arch’s terminal year LL-Adjusted EBITDA (which was equal to LL-Adjusted EBITDA for the calendar year ending December 31, 2028).

For purposes of selecting the reference range to apply to Arch’s estimated terminal year LL-Adjusted EBITDA, Moelis noted that (i) the selected reference range was primarily informed by the current and recent trading multiples for Arch and the Selected Companies (as defined below), with greater emphasis placed on the trading multiples for Arch over the last one-year time period, (ii) longer-dated historical trading multiples were considered but relied less upon due to the differences between the current and projected versus historical coal market dynamics, (iii) the similarities between the more normalized recent coal pricing environments and the coal pricing assumptions underpinning the financial projections received from Arch management and (iv) the implied trading multiple premium of Arch relative to that of CONSOL over the last one- and two-year time periods. Based on the foregoing analysis and its professional judgment and experience, Moelis selected a terminal multiple range of 4.50x to 5.50x Arch’s estimated terminal year LL-Adjusted EBITDA. Moelis then applied such multiple range to Arch’s estimated terminal year LL-Adjusted EBITDA based on the August 2024 Arch Projections to calculate the estimated terminal values.

In calculating the implied equity value of Arch, Moelis separately valued the NOLs of Arch by utilizing the NOL balance of approximately $359 million as of June 30, 2024 and taking into account Arch’s projected NOL utilization and cash tax savings, based on a U.S. federal corporate tax rate assumption, each as provided by Arch management. For the purpose of discounting the estimated tax savings, Moelis utilized a range of discount rates

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of 9.25% to 12.75% based on an estimated range of Arch’s cost of equity. Moelis also removed the income statement and free cash flow impacts of the legacy liabilities for Arch and treated these liabilities as net debt adjustments.

The standalone implied range of equity values for Arch and implied range of share prices for the Arch common stock derived from the DCF analysis for Arch are presented below:

DCF-Based Exchange Ratio and Ownership Percentage Analysis

Based on the standalone implied range of share prices for the CONSOL common stock and the Arch common stock presented in the standalone DCF analyses above, Moelis calculated a range of implied exchange ratios, which are presented below. Based on the standalone implied range of equity values for CONSOL and Arch presented in the standalone DCF analyses above, Moelis also calculated a range of implied pro forma ownership percentages of CONSOL in the combined company after giving effect to the merger (the “implied pro forma CONSOL ownership percentage”), which are presented below:

Moelis compared (i) the range of the implied exchange ratios above to the exchange ratio of 1.326x in the merger and (ii) the range of the implied pro forma CONSOL ownership percentages above to the pro forma CONSOL ownership percentage of approximately 55.0% (assuming an exchange ratio of 1.326x in the merger).

Selected Publicly Traded Companies Analysis—Standalone

Moelis performed a selected publicly traded companies analysis of each of CONSOL and Arch. Financial data for the selected publicly traded companies was based on public filings and other publicly available information available as of August 19, 2024. In performing a selected publicly traded companies analysis of each of CONSOL and Arch, Moelis reviewed and analyzed, among other things, Adjusted TEV of the selected publicly traded companies as a multiple of both estimated LL-Adjusted EBITDA for the calendar year ending December 31, 2024 (“2024E LL-Adjusted EBITDA”) and estimated LL-Adjusted EBITDA for the calendar year ending December 31, 2025 (“2025E LL-Adjusted EBITDA”), and certain other financial information and market trading data related to the following selected publicly traded companies that Moelis believed, based on its professional judgment and experience, were generally relevant in certain respects to CONSOL and Arch for purposes of its analysis.

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Moelis selected publicly traded companies that operate in North America that extract, process and market metallurgical and/or thermal coal, and considered selected publicly traded companies on the basis of business models, scale, geographic presence and corporate structure, among other factors. Although none of the Selected Companies (as defined below) are directly comparable to CONSOL or Arch, the Selected Companies were selected by Moelis, based on its professional judgment and experience.

Moelis considered, but ultimately excluded from its analysis, large cap diversified mining companies with significant coal production given that, while these large cap diversified mining companies produce comparable coal types / products as CONSOL and Arch, Moelis viewed them as less relevant due to the fact that their coal mines are predominantly outside of North America, and they have significant commodity diversification outside of coal.

Below are the publicly traded companies (the “Selected Companies”) Moelis considered in its analysis:

Moelis used Wall Street research analyst consensus estimates as of August 19, 2024 (which are referred to herein as “consensus estimates”) to derive 2024E LL-Adjusted EBITDA and 2025E LL-Adjusted EBITDA for the Selected Companies, including CONSOL and Arch.

The following table summarizes the Adjusted TEV to 2024E LL-Adjusted EBITDA and 2025E LL-Adjusted EBITDA multiples for the Selected Companies, as well as CONSOL and Arch:

CONSOL

In determining the selected reference ranges to apply to CONSOL’s estimated financial metrics, Moelis noted that the selected reference ranges were informed (i) primarily by CONSOL’s current trading multiples given its business mix and relative exposure to API2 coal prices as compared to the Selected Companies and (ii) to some extent, by the corresponding trading multiples of the Selected Companies.

Based on the foregoing analysis and its professional judgement and experience, Moelis selected (i) a reference range for Adjusted TEV / 2024E LL-Adjusted EBITDA multiples for CONSOL of 4.25x to 5.25x and (ii) a

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reference range for Adjusted TEV / 2025E LL-Adjusted EBITDA multiples for CONSOL of 4.00x to 5.00x. Moelis then applied these multiples to CONSOL’s 2024E LL-Adjusted EBITDA and 2025E LL-Adjusted EBITDA based on the August 2024 CONSOL Projections.

The standalone implied range of equity values for CONSOL and implied range of share prices for CONSOL common stock derived from the selected publicly traded companies analysis for CONSOL are presented below:

Arch

In determining the selected reference ranges to apply to Arch’s estimated financial metrics, Moelis noted that the selected reference ranges were informed (i) by Arch’s current trading multiples and (ii) by the corresponding trading multiples of the Selected Companies that are primarily met coal producers.

Based on the foregoing analysis and its professional judgment and experience, Moelis selected (i) a reference range for Adjusted TEV / 2024E LL-Adjusted EBITDA multiples for Arch of 4.75x to 5.75x and (ii) a reference range for Adjusted TEV / 2025E LL-Adjusted EBITDA multiples for CONSOL of 3.75x to 4.75x. Moelis then applied these multiples to Arch’s 2024E LL-Adjusted EBITDA and 2025E LL-Adjusted EBITDA based on the August 2024 Arch Projections.

The standalone implied range of equity values for Arch and implied range of share prices for Arch common stock derived from the selected publicly traded companies analysis for Arch are presented below:

Selected Publicly Traded Companies-Based Implied Exchange Ratio Analysis

Based on the standalone implied range of equity values for CONSOL and Arch and implied range of share prices for the CONSOL common stock and the Arch common stock described above, Moelis calculated a range of implied exchange ratios and implied pro forma CONSOL ownership percentages, which are presented below:

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Moelis compared (i) the range of implied exchange ratios above to the exchange ratio of 1.326x in the merger and (ii) the range of the implied pro forma CONSOL ownership percentages above to the pro forma CONSOL ownership percentage of approximately 55.0% (assuming an exchange ratio of 1.326x in the merger).

Summary of Pro Forma Transaction Analysis

DCF-Based Has/Gets Analysis

Moelis performed a DCF-based has/gets analysis to calculate the equity value uplift to CONSOL implied by the merger. This has/gets analysis compared (i) the standalone implied equity value of CONSOL based on the DCF analysis of CONSOL (the “has”) with (ii) the implied value of the pro forma equity in the combined company that will be owned by the pre-merger holders of CONSOL common stock after giving effect to the merger (assuming a pro forma CONSOL ownership percentage of approximately 55.0% and an exchange ratio of 1.326x in the merger) (the “gets”).

To calculate the implied pro forma DCF equity value of the combined company after giving effect to the merger, Moelis utilized (i) the implied standalone DCF equity value ranges (including NOLs, if applicable) for CONSOL and Arch (described above under the heading “—Discounted Cash Flow Analysis—Standalone”), (ii) the implied present value range of estimated annual synergies of $125 million (representing the midpoint of a range of $110—$140 million, net of non-equity costs to achieve those synergies of $60 million (representing the midpoint of a range of $50—$70 million)), all as provided by the management of CONSOL and Arch, derived using (A) a range of discount rates of 8.75% to 11.50% based on the estimated pro forma WACC ranges for each of CONSOL and Arch and (B) a terminal year Adjusted EBITDA multiple range of 4.23x to 5.23x based on the weighted average of the selected terminal year LL-Adjusted EBITDA multiple ranges for each of CONSOL and Arch, (iii) the implied present value range of NOL dis-synergies (calculated as the difference between the net present value of the Arch pre-merger NOLs and the net present value of the pro forma combined company NOLs), (iv) estimated transaction expenses of $50 million as provided by CONSOL management and Arch management and (v) cost of capital synergies (calculated by comparing the standalone implied equity value of CONSOL and Arch based on the DCF analysis of CONSOL and Arch against a similar DCF analysis computed utilizing a WACC range derived based on a size premium which correlated to the size of the pro forma combined company).

The following table summarizes the results of the DCF-based has/gets analysis:

2024E Trading Multiples-Based Has/Gets Analysis

Moelis performed a trading multiples-based has/gets analysis to calculate the equity value uplift to CONSOL common stock implied by the merger. This has/gets analysis compared (i) the standalone equity value of CONSOL of $2,863 million as of August 19, 2024 (based on the closing trading price of the CONSOL common stock of $95.81 per share on August 19, 2024) (the “has”) with (ii) the implied value of the pro forma synergized equity value of the combined company that will be owned by the pre-merger holders of CONSOL common stock after giving effect to the merger (assuming a pro forma CONSOL ownership percentage of approximately 55.0% and an exchange ratio of 1.326x in the merger) (the “gets”).

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To calculate the implied pro forma value of the combined company after giving effect to the merger, Moelis utilized (i) the standalone equity value of CONSOL of $2,863 million as of August 19, 2024 (based on the closing trading price of the CONSOL common stock of $95.81 per share on August 19, 2024) and the standalone equity value of Arch of $2,345 million as of August 19, 2024 (based on the closing trading price of the Arch common stock of $127.00 on August 19, 2024), (ii) the implied value of estimated annual synergies of $125 million (representing the midpoint of a range of $110—$140 million), as provided by CONSOL management and Arch management (valued at $615 million assuming an illustrative 2024E LL-Adjusted EBITDA blended trading multiple of 4.9x), (iii) non-equity related costs to achieve those synergies of $60 million and (iv) estimated transaction expenses of $50 million, all as provided by CONSOL management and Arch management.

The following table summarizes the results of the 2024E trading multiples-based has/gets analysis:

2025E Trading Multiples-Based Has/Gets Analysis

Moelis performed a trading multiples-based has/gets analysis to calculate the equity value uplift to CONSOL common stock implied by the merger. This has/gets analysis compared (i) the standalone equity value of CONSOL of $2,863 million as of August 19, 2024 (based on the closing trading price of the CONSOL common stock of $95.81 per share on August 19, 2024) (the “has”) with (ii) the implied value of the pro forma synergized equity value of the combined company that will be owned by the pre-merger holders of CONSOL common stock after giving effect to the merger (assuming a pro forma CONSOL ownership percentage of approximately 55.0% and an exchange ratio of 1.326x in the merger) (the “gets”).

To calculate the implied pro forma value of the combined company after giving effect to the merger, Moelis utilized (i) the standalone equity value of CONSOL of $2,863 million as of August 19, 2024 (based on the closing trading price of the CONSOL common stock of $95.81 per share on August 19, 2024) and the standalone equity value of Arch of $2,345 million as of August 19, 2024 (based on the closing trading price of the Arch common stock of $127.00 on August 19, 2024), (ii) the implied value of estimated annual synergies of $125 million (representing the midpoint of a range of $110—$140 million), as provided by CONSOL management and Arch management (valued at $461 million assuming an illustrative 2025E LL-Adjusted EBITDA blended trading multiple of 3.7x), (iii) non-equity related costs to achieve those synergies of $60 million and (iv) estimated transaction expenses of $50 million, all as provided by CONSOL management and Arch management.

The following table summarizes the results of the 2025E trading multiples-based has/gets analysis: