2seventy bio (TSVT) DEF 14ADefinitive proxy

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

______________________________________________

SCHEDULE 14A INFORMATION

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

(Amendment No. )

______________________________________________

Check the appropriate box:

(Name of Person(s) Filing Proxy Statement, if Other Than The Registrant)

Payment of Filing Fee (Check all boxes that apply):

Dear Stockholder:

You are cordially invited to attend the 2024 Annual Meeting of Stockholders of 2seventy bio, Inc. We intend to hold the Annual Meeting on June 10, 2024 at 8:00 a.m. EDT. The Annual Meeting will be held in a virtual meeting format only via the Internet, with no physical in-person meeting. You will be able to attend and participate in the Annual Meeting online by visiting the meeting center at www.virtualshareholdermeeting.com/TSVT2024 and entering your control number found on your enclosed proxy card, where you will be able to listen to the Annual Meeting live, submit questions and vote. We encourage you to vote your shares prior to the Annual Meeting.

Details regarding admission to the Annual Meeting and the business to be conducted are more fully described in the accompanying Notice of Annual Meeting and Proxy Statement. At this Annual Meeting, the agenda includes the election of three Class III directors for three-year terms and the ratification of the appointment of Ernst & Young LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2024.

Under Securities and Exchange Commission rules, we are providing access to the proxy materials for the Annual Meeting to stockholders via the Internet. Accordingly, you can access the proxy materials and vote at www.proxyvote.com. Instructions for accessing the proxy materials and voting are described below and in the Notice of Annual Meeting that you received in the mail. Your vote is very important. Whether or not you plan to attend the Annual Meeting, please carefully review our proxy statement and then cast your vote, regardless of the number of shares you hold. If you are a stockholder of record, you may vote over the Internet, by telephone, or, if you request to receive a printed set of the proxy materials, by completing, signing, dating and mailing the accompanying proxy card in the return envelope. Submitting your vote via the Internet or by telephone or proxy card will not affect your right to vote at the Annual Meeting if you decide to attend the Annual Meeting virtually. If your shares are held in street name (held for your account by a broker or other nominee), you will receive instructions from your broker or other nominee explaining how to vote your shares, and you will have the option to cast your vote by telephone or over the Internet if your voting instruction form from your broker or nominee includes instructions and a toll-free telephone number or Internet website to do so. In any event, to be sure that your vote will be received in time, please cast your vote by your choice of available means at your earliest convenience.

We hope that you will join us on June 10, 2024. Your continuing interest in 2seventy is very much appreciated.

Cambridge, Massachusetts

April 25, 2024

2seventy bio, Inc. (“2seventy bio” or “the Company”) is an “emerging growth company” under applicable federal securities laws and therefore permitted to conform with certain reduced public company reporting requirements. As an emerging growth company, we provide in this proxy statement the scaled disclosure permitted under the Jumpstart Our Business Startups Act of 2012, including the compensation disclosures required of a “smaller reporting company,” as that term is defined in Rule 12b-2 promulgated under the Securities Exchange Act of 1934, as amended (the "Exchange Act"). In addition, as an emerging growth company, we are not required to conduct votes seeking approval, on an advisory basis, of the compensation of our named executive officers or the frequency with which such votes must be conducted or required to provide pay versus performance disclosure under Item 402(v) of Regulation S-K. We will remain an “emerging growth company” until the earliest of (i) the last day of the fiscal year following the fifth anniversary of becoming a public company; (ii) the last day of the fiscal year in which our total annual gross revenue is equal to or more than $1.235 billion; (iii) the date on which we have issued more than $1 billion in nonconvertible debt during the previous three years; or (iv) the date on which we are deemed to be a large accelerated filer under the rules of the Securities and Exchange Commission (the "SEC").

When are this proxy statement and the accompanying materials scheduled to be sent to stockholders?

We have elected to provide access to our proxy materials to our stockholders via the Internet. Accordingly, on or about April 25, 2024, we will begin mailing a Notice of Internet Availability of Proxy Materials (the "Notice of Internet Availability" or "Notice") and the proxy materials, including the Notice of 2024 Annual Meeting of Stockholders, this proxy statement and accompanying proxy card or, for shares held in street name (held for your account by a broker or other nominee), the voting instruction form, and the Annual Report on Form 10-K for the year ended December 31, 2023 will be made available to stockholders on the Internet on the same date.

Why did I receive a Notice of Internet Availability of Proxy Materials instead of a full set of proxy materials?

Pursuant to rules adopted by the SEC, we are providing access to our proxy materials over the Internet rather than printing and mailing the proxy materials. We believe electronic delivery will expedite the receipt of materials and will help lower our costs and reduce the environmental impact of our annual meeting materials. Therefore, a Notice of Internet Availability will be mailed to holders of record and beneficial owners of our common stock starting on or around April 25, 2024. The Notice of Internet Availability will provide instructions as to how stockholders may access and review the proxy materials, including the Notice of Annual Meeting, proxy statement, proxy card and Annual Report on Form 10-K, on the website referred to in the Notice of Internet Availability or, alternatively, how to request that a copy of the proxy materials, including a proxy card, be sent to them by mail. The Notice of Internet Availability will also provide voting instructions. In addition, stockholders of record may request to receive the proxy materials in printed form by mail or electronically by e-mail on an ongoing basis for future stockholder meetings. Please note that, while our proxy materials are available at the website referenced in the Notice of Internet Availability, and our Notice of Annual Meeting, proxy statement and Annual Report on Form 10-K are available on our website, no other information contained on either website is incorporated by reference in or considered to be a part of this document.

To attend and participate in the Annual Meeting, stockholders will need to access the live audio webcast of the meeting. To do so, you will need to log in at www.virtualshareholdermeeting.com/TSVT2024 and use your sixteen-digit control number, which can be found on the Notice, voting instruction form or proxy card you received. If your shares are held in “street name” through a bank, broker or other nominee and you do not have a sixteen-digit control number, you must contact such broker, bank or nominee so that you can be provided with a control number or legal proxy. Those without a control number may attend as guests of the Annual Meeting but will not have the option to vote or ask questions during the meeting.

Will I be able to ask questions during the Annual Meeting?

If you have logged into the Annual Meeting using your sixteen-digit control number and wish to ask a question during the meeting, you may do so on the virtual meeting website by typing your question into the “Ask a Question” field, and clicking “Submit.” Those without a control number will not have the option to ask questions during the meeting.

If questions submitted are repetitive as to a particular topic, the Chair of the meeting may limit discussion on such topic. During the formal portion of the meeting, all questions presented should relate directly to the proposal under discussion. We will also hold a question and answer period at the end of the meeting, as time permits, during which time we welcome questions not relating to specific proposals.

For further details, please review the Annual Meeting’s Rules of Conduct, which will be posted on www.virtualshareholdermeeting.com/TSVT2024 during the Annual Meeting. Following the Annual Meeting, an

archived replay of the audio webcast will be available on the Investor Relations section of our website for approximately thirty (30) days thereafter.

Beginning fifteen (15) minutes prior to the start of and during the Annual Meeting, we will have technicians ready to assist you with any technical difficulties you may have accessing or hearing the virtual meeting or submitting questions. If you encounter any difficulties accessing the virtual meeting during the check-in or meeting time, please call the technical support number that will be posted on the Virtual Shareholder Meeting log in page.

Who is soliciting my vote?

The Board of Directors of 2seventy bio, Inc. (the "Board") is soliciting your vote for the 2024 Annual Meeting of Stockholders.

When is the record date for the Annual Meeting?

The Board has fixed the record date for the Annual Meeting as of the close of business on April 19, 2024.

How many votes can be cast by all stockholders?

A total of 51,404,837 shares of our common stock were outstanding on April 19, 2024, all of which are entitled to be voted at the Annual Meeting with respect to all matters to be acted upon at the Annual Meeting. Each stockholder of record is entitled to one vote on each matter for each share of our common stock held by such stockholder. None of our shares of undesignated preferred stock were outstanding on the record date.

How do I vote?

By attending the Annual Meeting Online

If you are a stockholder of record, you may vote online at the Annual Meeting by attending the Annual Meeting online and following the instructions posted at www.virtualshareholdermeeting.com/TSVT2024. If you hold your shares through a bank or broker and wish to vote online at the meeting, you must obtain a valid proxy from the firm that holds your shares.

By Proxy

If you do not wish to attend the Annual Meeting online, you may vote by proxy. You can vote by proxy over the Internet by following the instructions provided in the Notice, or, if you requested printed copies of the proxy materials by mail, you can vote by mailing your proxy as described in the proxy materials. In order to be counted, proxies submitted by Internet must be received by the cutoff time of 11:59 p.m. Eastern Time on June 9, 2024. Proxies submitted by mail must be received before the start of the Annual Meeting.

If you complete and submit your proxy before the Annual Meeting, the persons named as proxies will vote the shares represented by your proxy in accordance with your instructions. If you submit a proxy without giving voting instructions, your shares will be voted in the manner recommended by the Board on all matters presented in this proxy statement, and as the persons named as proxies may determine in their discretion with respect to any other matters properly presented at the Annual Meeting. You may also authorize another person or persons to act for you as proxy in a writing, signed by you or your authorized representative, specifying the details of those proxies’ authority. The original writing must be given to each of the named proxies, although it may be sent to them by electronic transmission if, from that transmission, it can be determined that the transmission was authorized by you.

If any other matters are properly presented for consideration at the Annual Meeting, including, among other things, consideration of a motion to adjourn the Annual Meeting to another time or place (including, without limitation, for the purpose of soliciting additional proxies), the persons named in your proxy and acting thereunder will have discretion to vote on those matters in accordance with their best judgment. We do not currently anticipate that any other matters will be raised at the Annual Meeting.

What are the Board’s recommendations on how to vote my shares?

Who pays the cost for soliciting proxies?

We will pay the cost for the solicitation of proxies by the Board. The solicitation of proxies will be made primarily by mail and through Internet access to materials. Proxies may also be solicited personally, by telephone, fax or e-mail by employees of 2seventy bio without any remuneration to such individuals other than their regular compensation. We will also reimburse brokers, banks, custodians, other nominees and fiduciaries for forwarding these materials to their principals to obtain the authorization for the execution of proxies.

Will my shares be voted if I do not return my proxy?

If your shares are registered directly in your name, your shares will not be voted if you do not vote over the Internet, by telephone, by returning your proxy or by ballot at the Annual Meeting. If your shares are held in street name, your bank, broker or other nominee may under certain circumstances vote your shares if you do not timely return your proxy. Banks, brokers and other nominees can vote customers’ unvoted shares on routine matters, but cannot vote such shares on non-routine matters. If you do not timely return a proxy to your bank, broker or other nominee to vote your shares, your bank, broker or other nominee may, on routine matters, either vote your shares or leave your shares unvoted. Your bank, broker or other nominee cannot vote your shares on any non-routine matter. The election of directors (Proposal 1) is a non-routine matter. The ratification of the appointment of our independent registered public accounting firm (Proposal 2) is a routine matter. We encourage you to provide voting instructions to your bank, broker or other nominee by giving your proxy to them. This ensures that your shares will be voted at the Annual Meeting according to your instructions. You should receive directions from your bank, broker or other nominee about how to submit your proxy to them at the time you receive this proxy statement.

How do I revoke my proxy?

If you are a stockholder of record, you may revoke your proxy by (1) following the instructions on the Notice and entering a new vote over the Internet or by telephone by the cutoff time of 11:59 p.m. Eastern Time on June 9, 2024, (2) attending the Annual Meeting online and voting by following the instructions at www.virtualshareholdermeeting.com/TSVT2024 or (3) by filing an instrument in writing revoking the proxy or submitting another duly executed proxy card bearing a later date with our Corporate Secretary. Any written notice of revocation or subsequent proxy card must be received by our Corporate Secretary prior to the taking of the vote at the Annual Meeting. Such written notice of revocation or subsequent proxy card should be hand delivered to our Corporate Secretary or sent to our principal executive offices at 60 Binney Street, Cambridge, Massachusetts 02142, Attention: Corporate Secretary.

If a broker, bank or other nominee holds your shares, you must contact such broker, bank or nominee in order to find out how to change your vote.

How is a quorum reached?

The presence, in person or by proxy, of at least a majority of the shares entitled to vote is necessary to constitute a quorum for the transaction of business at the Annual Meeting. Shares held of record by stockholders or brokers, bankers or other nominees who do not return a signed and dated proxy or attend the Annual Meeting in person will not be considered present or represented at the Annual Meeting and will not be counted in determining the presence of a quorum. Under the General Corporation Law of the State of Delaware, shares that are voted “abstain” or “withheld” and broker “non-votes” are counted as present for purposes of determining whether a quorum is present at the Annual Meeting. If a quorum is not present, the meeting may be adjourned until a quorum is obtained.

What vote is required to approve each item and how are votes counted?

Votes cast by proxy or in person at the Annual Meeting will be counted by the persons appointed by 2seventy bio to act as tabulators for the meeting. The tabulators will count all votes FOR and AGAINST, votes withheld, abstentions, and broker non-votes, as applicable, for each matter to be voted on at the Annual Meeting. A broker non-vote occurs when a nominee holding shares for a beneficial owner does not vote on a particular proposal

because the nominee does not have discretionary voting power with respect to that item and has not received instructions from the beneficial owner.

Could other matters be decided at the Annual Meeting?

2seventy bio does not know of any other matters that may be presented for action at the Annual Meeting. Should any other business come before the meeting, the persons named on the enclosed proxy will have discretionary authority to vote the shares represented by such proxies in accordance with their best judgment. If you hold shares through a broker, bank or other nominee as described above, they will not be able to vote your shares on any other business that comes before the Annual Meeting unless they receive instructions from you with respect to such matter.

What happens if the meeting is postponed or adjourned?

If you have completed a proxy, your proxy may be voted at the postponed or adjourned meeting. You will still be able to revoke and change your proxy until it is voted.

How can I find out the results of the voting at the Annual Meeting?

Preliminary voting results will be announced at the Annual Meeting. Final voting results will be published in a Current Report on Form 8-K, that we expect to file with the SEC within four business days after the Annual Meeting. If final voting results are not available to us in time to file a Form 8-K within four business days after the Annual Meeting, we intend to file a Form 8-K to publish preliminary results and, within four business days after the final results are known to us, file an additional Form 8-K to publish the final results.

What does it mean if I receive more than one proxy card or voting instruction form?

It means that you have multiple accounts at the transfer agent or with brokers. Please complete and return all proxy cards or voting instruction forms to ensure that all of your shares are voted.

In accordance with Delaware law and our Amended and Restated Certificate of Incorporation and By-laws, our Board is divided into three classes of approximately equal size. The members of each class are elected to serve a three-year term with the term of office of each class ending in successive years. Denice Torres, Marcela Maus, M.D., Ph.D. and Eli Casdin are the directors whose terms expire at this Annual Meeting. Each of Denice Torres, Marcela Maus, M.D., Ph.D. and Eli Casdin has been nominated for and has agreed to stand for re-election to our Board to serve as a Class III director until the 2027 Annual Meeting and until his or her successor is duly elected.

Our By-laws provide for a plurality voting standard for the election of directors. It is intended that, unless you give contrary instructions, shares represented by proxies solicited by the Board will be voted for the election of the three director nominees listed below. We have no reason to believe that any director nominee will be unavailable for election at the Annual Meeting. In the event that one or more director nominees is unexpectedly not available to serve, proxies may be voted for another person nominated as a substitute by the Board, or the Board may reduce the number of directors to be elected at the Annual Meeting. Information relating to each director nominee and for each continuing director, including his or her period of service as a director of 2seventy bio, principal occupation and other biographical material is shown below.

Board Composition

At each Annual Meeting, the successors to directors whose terms will then expire shall serve from the time of election and qualification until the third Annual Meeting following election and until their successors are duly elected and qualified. A resolution of the Board may change the authorized number of directors. Any additional directorships resulting from an increase in the number of directors will be distributed among the three classes so that, as nearly as possible, each class will consist of one-third of the directors. This classification of the Board may have the effect of delaying or preventing changes in control or management of our Company.

There are no family relationships between or among any of our directors or executive officers. There is no arrangement or understanding between any of our directors and any other person or persons pursuant to which he or she is to be selected as a director. There are no material legal proceedings to which any of our directors is a party adverse to us or our subsidiary or in which any such person has a material interest adverse to us or our subsidiary.

Our Board is responsible for selecting its own members. The Board delegates the selection and nomination process to the Nominating and Corporate Governance Committee, with the expectation that other members of the Board, and of management, will be requested to take part in the process as appropriate.

Generally, our Nominating and Corporate Governance Committee together with our management team identifies candidates for director nominees, through the use of search firms or other advisors, and through the recommendations submitted by stockholders or through such other methods as the Nominating and Corporate Governance Committee deems to be helpful in identifying candidates. Once candidates have been identified, our Nominating and Corporate Governance Committee confirms that the candidates meet all of the minimum qualifications for director nominees established by the Nominating and Corporate Governance Committee. The Nominating and Corporate Governance Committee working with management may gather information about the candidates through interviews, detailed questionnaires, background checks or any other means that the Nominating and Corporate Governance Committee deems to be appropriate in the evaluation process. The Nominating and Corporate Governance Committee then meets as a group to discuss and evaluate the qualities and skills of each candidate, both on an individual basis and taking into account the overall composition and needs of our Board. Based on the results of the evaluation process, the Nominating and Corporate Governance Committee recommends candidates for the Board’s approval as director nominees for election to the Board.

Director Qualifications and Diversity

Our Nominating and Corporate Governance Committee will consider, among other things, the following qualifications, skills and attributes when recommending candidates for the selection as director nominees for the Board and as candidates for appointment to its committees: a director nominee shall have the highest personal and

professional integrity, shall have demonstrated exceptional ability and judgment, and shall be most effective, in conjunction with the other director nominees to the Board, in collectively serving the long-term interests of the stockholders.

In evaluating proposed director candidates, our Nominating and Corporate Governance Committee may consider, in addition to the minimum qualifications and other criteria for Board membership approved by the Board from time to time, all facts and circumstances that it deems appropriate or advisable, including, among other things, diversity considerations, the skills of the proposed director candidate, his or her depth and breadth of professional experience or other background characteristics, his or her independence, and the needs of the Board. Our corporate governance guidelines also provide that diversity on the Board should be considered by our Nominating and Corporate Governance Committee in the director evaluation and nomination process. While we do not have a formal policy with respect to diversity, our Nominating and Corporate Governance Committee believes that it is essential that the members of the Board represent diverse viewpoints. Our Nominating and Corporate Governance Committee believes that the backgrounds and qualifications of our directors, considered as a group, should provide a composite mix of experience, knowledge and abilities that will allow our Board to promote our strategic objectives and fulfill its responsibilities to our stockholders, and considers diversity of gender, race, national origin, education, professional experience, and differences in viewpoints and skills when evaluating proposed director candidates.

Our Nominating and Corporate Governance Committee’s priority in selecting directors is identification of persons who will further our interests through his or her established record of professional accomplishment, the ability to contribute positively to the collaborative culture among directors, and professional and personal experiences and expertise relevant to our growth strategy. The Nominating and Corporate Governance Committee will consider candidates recommended by stockholders.

The composition of our Board currently includes four individuals who are diverse under the Nasdaq listing rule regarding board diversity, as presented in the below Board Diversity Matrix. Under the applicable Nasdaq listing rule, directors who self-identify as (i) female, (ii) an underrepresented minority, or (iii) LGBTQ+ are defined as being diverse.

Board Independence

Our Board has determined, upon the recommendation of our Nominating and Corporate Governance Committee, that each of our directors, other than Mr. Baird, who serves as our President and Chief Executive Officer, and Mr. Leschly, who serves as the Chair of our Board and previously served as our Chief Executive Officer, has no relationship that would interfere with the exercise of independent judgment in carrying out the responsibilities of a director and is independent within the meaning of the director independence standards of the Nasdaq Stock Market rules and the SEC. At least annually, our Board evaluates all relationships between us and

each director in light of relevant facts and circumstances for the purposes of determining whether a material relationship exists that might signal a potential conflict of interest or otherwise interfere with such director’s ability to satisfy his or her responsibilities as an independent director. Based on this evaluation, our Board makes an annual determination of whether each director is independent within the meaning of the Nasdaq Stock Market rules and the SEC independence standards.

Board Meetings and Attendance

Board Committees

Audit Committee

Compensation Committee

Our Compensation Committee is currently composed of Mr. Lynch, Ms. Torres and Ms. Glickman, with Mr. Lynch serving as chair of the committee. Our Board has determined each member of the Compensation Committee is “independent” as defined under the applicable listing standards of Nasdaq. In addition, each member qualifies as a non-employee director, as defined in Rule 16b-3 of the Exchange Act. During the fiscal year ended December 31, 2023, the Compensation Committee met six times. The Compensation Committee’s responsibilities include, among other duties:

Nominating and Corporate Governance Committee

Our Nominating and Corporate Governance Committee is composed of Ms. Torres, Dr. Maus, and Dr. Lin, with Ms. Torres serving as chair of the committee. Our Board has determined that each member of the Nominating and Corporate Governance Committee is “independent” as defined under the applicable listing standards of Nasdaq. The Nominating and Corporate Governance Committee did not meet during the fiscal year ended December 31, 2023, but transacted the Nominating and Corporate Governance Committee business via unanimous written consents. The Nominating and Corporate Governance Committee’s responsibilities include, among other duties:

Non-Management Director Meetings

In addition to the meetings of the committees of the Board described above, in connection with the Board meetings, the non-management directors met four times in executive session during the fiscal year ended December 31, 2023. The Chair of the Board presides at these executive sessions. The Audit Committee and the Board have established a procedure whereby interested parties may make their concerns known to non-management directors, which is described on our website.

Leadership Structure and Risk Oversight

Our Board is currently chaired by Mr. Leschly and Ms. Torres serves as our Lead Independent Director. As a general policy, our Board believes that separation of the positions of Chair and Chief Executive Officer reinforces the independence of the Board from management, creates an environment that encourages objective oversight of management’s performance and enhances the effectiveness of the Board as a whole. If the position of Chair is held by a non-independent director, then the Board may select an independent director to serve as Lead Independent Director. The responsibilities of the Lead Independent Director include presiding at executive sessions of independent directors and serving as a liaison between our Chief Executive Officer and the independent directors. Mr. Baird serves as our President and Chief Executive Officer while Mr. Leschly serves as the Chair of our Board but is not an officer of the Company and Ms. Torres is our Lead Independent Director.

Our Board performs its oversight role by using several different levels of review. Our Chair and Lead Independent Director meet regularly with our Chief Executive Officer and other executive officers to discuss our strategy and material risks. Members of senior management attend the quarterly Board meetings, present on strategic matters involving our business, and are available to address any questions or concerns raised by the Board on risk management-related issues and any other matters. Our Board reviews the risks, including any environmental or social governance risks, associated with our business strategies periodically throughout the year as part of its consideration of undertaking any such business strategies.

Each of the committees of our Board also oversees the management of our risk that falls within the committee’s areas of responsibility. In performing this function, each committee has full access to management, as well as the ability to engage advisors. The Audit Committee oversees our enterprise risk management program as it relates to our operations by identifying the primary risks associated with our operations and corporate functions, receiving periodic updates on activities to manage such risks, and providing reports to the Board regarding such activities. In carrying out its responsibilities for the oversight of operational risk management, members of the Audit Committee regularly discuss with management our risk exposures in the areas of financial reporting, internal controls, cyber and information security, and our legal and regulatory compliance programs, and the steps we take to manage them. Our Audit Committee also meets privately with representatives from our independent registered public accounting firm as part of its oversight of our risk management. The Compensation Committee assists the Board in fulfilling its oversight responsibilities with respect to the management of risks arising from our compensation policies and programs and succession planning for our executive officers, and evaluates potential risks associated with independent director compensation for consideration by the full Board. The Nominating and Corporate Governance Committee assists the Board in fulfilling its oversight responsibilities with respect to the management of risks associated with Board organization, membership and structure, succession planning for our directors, and corporate governance.

Compensation Committee Interlocks and Insider Participation

Mr. Lynch, Ms. Torres and Ms. Glickman served as members of our Compensation Committee during the year ended December 31, 2023. None of the members of our Compensation Committee has at any time been one of our officers or employees. None of our executive officers currently serves, or in the past fiscal year has served, as a member of the board of directors or on a compensation committee of any entity that has one or more executive

Code of Business Conduct and Ethics and Corporate Governance Guidelines

The following table sets forth information regarding our executive officers and certain key employees as of April 19, 2024:

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Overview

The Company entered into an asset purchase agreement (the “Asset Purchase Agreement”) with Regeneron Pharmaceuticals, Inc. on January 29, 2024 for the sale of the Company’s oncology and autoimmune research and development programs, clinical manufacturing capabilities, and related platform technologies to Regeneron. On April 1, 2024, the Company completed the transactions contemplated by the Asset Purchase Agreement (the “Asset Sale Closing”). Effective as of the Asset Sale Closing, Mr. Baird was appointed as our Chief Executive Officer and Mr. Leschly transitioned to Chair of our Board. Also effective as of the Asset Sale Closing, Ms. Eatwell was appointed as our Chief Financial Officer, Ms. Snow was appointed as our Senior Vice President of Quality & Head of Operations and Dr. Gregory resigned as our Chief Scientific Officer.

Narrative Disclosure to the Summary Compensation Table

Our Compensation Committee reviews and approves the compensation of our executive officers and is primarily responsible for determining the compensation for the named executive officers consistent with our overall executive compensation philosophy. Our Compensation Committee reviews and discusses the compensation of other

executive officers with the Chief Executive Officer and considers our overall performance against goals, individual executive performance, and internal and external equity as key factors in those decisions. Our Compensation Committee engaged Aon’s Human Capital Solutions practice, a division of Aon plc ("Aon"), as its independent compensation consultant to advise on executive and Board compensation matters including: overall compensation program design, peer group development and updates, and collection of market data. We develop our compensation programs after reviewing publicly available compensation data and also subscribe to Aon’s various global and specialized life sciences and general industry surveys on an ongoing basis. Aon advised the Compensation Committee on all of the principal aspects of executive compensation for the periods following the separation. Aon consultants attend meetings of the Compensation Committee when requested to do so. Aon reports directly to the Compensation Committee and not to management, although it meets with management for purposes of gathering information for its analyses and recommendations. The Compensation Committee has assessed the independence of Aon consistent with SEC regulations and Nasdaq listing standards and has concluded that the engagement of Aon does not raise any conflict of interest.

 

 

Equity-Based Compensation

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to those employees 50 years of age or older), and to have the amount of this deferral contributed to the 401(k) plan. We make matching contributions and other employer contributions on behalf of eligible employees under our 401(k) plan. For fiscal year 2023, we matched a portion of eligible employee contributions equal to 100% of the first 4% of eligible contributions pursuant to the 401(k) plan’s matching formula.

No hedging transactions with our securities

Employment Agreements With our Named Executive Officers in Effect During 2023

In addition, in the event that Mr. Baird terminates his employment with us for good reason or his employment with us is terminated by us without cause in either case within 12 months following a “sale event” (as defined in the 2021

Plan), he is entitled to receive the following payments and benefits (in lieu of the payments and benefits described above) upon the timely execution of a separation agreement, including a general release of claims:

Director Compensation

The following table sets forth the amount of our common stock beneficially owned, directly or indirectly, as of April 16, 2024, by (i) each of our current directors, (ii) each of our named executive officers, (iii) all of our directors and executive officers as a group, and (iv) each person who is known to us to beneficially own more than 5% of the outstanding shares of our common stock, as determined through SEC filings, and the percentage of the common stock outstanding represented by each such amount. All shares of common stock shown in the table reflect sole voting and investment power except as otherwise noted.

Beneficial ownership is determined by the rules of the SEC and includes voting or investment power of the securities. As of April 16, 2024, we had 51,404,837 shares of common stock outstanding. Shares of common stock subject to stock options, which are now exercisable or are exercisable within 60 days after April 16, 2024, or RSUs vesting within 60 days after April 16, 2024 are to be considered outstanding for purposes of computing the percentage ownership of the persons holding these options or other rights but are not to be considered outstanding for the purpose of computing the percentage ownership of any other person. Unless otherwise indicated, the address for each person listed below is c/o 2seventy bio, Inc., 60 Binney Street, Cambridge, Massachusetts 02142.

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Equity compensation plan information

Procedures for related party transactions

We have adopted a related person transaction approval policy that governs the review of related person transactions at 2seventy bio. Pursuant to this policy, if we want to enter into a transaction with a related party or an affiliate of a related party, our Audit Committee will review the proposed transaction to determine, based on applicable rules of Nasdaq and the SEC, whether such transaction requires pre-approval by our Audit Committee or our Board. If pre-approval is required, the proposed transaction will be reviewed at the next regular or special meeting of our Audit Committee or our Board, as applicable. We may not enter into a related party transaction unless our Audit Committee has specifically confirmed in writing that either no further reviews are necessary or that all requisite corporate reviews have been obtained.

Transactions with related persons

The following is a description of transactions or series of transactions since January 1, 2023, to which we were or will be a party, in which:

Compensation arrangements for our named executive officers and our directors are described under “Director Compensation” and “Executive Compensation.”

Prior to the completion of the separation, all of our outstanding shares of common stock were owned by bluebird bio. Following the completion of the separation, bluebird bio no longer owns any shares of our common stock.

Following the completion of the separation, we and bluebird bio have operated separately, each as an independent public company. In connection with the separation, we and bluebird bio entered into certain agreements pursuant to which the separation of our business from bluebird bio was effected and that govern our relationship with bluebird bio going forward. The following is a summary of the terms of the material agreements that we entered into with bluebird bio in connection with the separation. These summaries set forth the terms of the agreements that we believe are material and are qualified in their entirety by reference to the full text of such agreements.

We entered into an intellectual property license agreement with bluebird bio pursuant to which each party has granted a license to certain intellectual property and technology. bluebird bio granted us a perpetual, worldwide, non-exclusive, royalty-free, fully paid-up license (or, as the case may be, sublicense) to certain intellectual property to allow us to use such intellectual property in connection with our ongoing and future research and development activities and product candidates. we granted to bluebird bio a perpetual, worldwide, non-exclusive, royalty-free, fully paid-up license (or, as the case may be, sublicense) to certain intellectual property for use in bluebird bio’s existing products and product candidates. Such licenses between the parties generally allow current or future uses of the intellectual property in connection with each party's respective fields.

We entered into a tax matters agreement with bluebird bio that governs bluebird bio’s and 2seventy bio's respective rights, responsibilities and obligations with respect to taxes (including taxes arising in the ordinary course of business and taxes, if any, incurred as a result of any failure of the distribution and certain related transactions to qualify as tax-free for U.S. federal income tax purposes), tax attributes, the preparation and filing of tax returns, the control of audits and other tax proceedings, and assistance and cooperation in respect of tax matters.

We entered into an employee matters agreement with bluebird bio. The employee matters agreement allocates assets, liabilities and responsibilities relating to the employment, compensation, and employee benefits of bluebird bio and 2seventy bio employees, and other related matters in connection with the separation, including the treatment of outstanding incentive equity awards and certain retirement and welfare benefit obligations. The employee matters agreement generally provides that, unless otherwise specified, we will be responsible for liabilities associated with employees who transferred to 2seventy bio and employees whose employment terminated prior to the distribution but who primarily supported the 2seventy bio business, whether incurred prior to or after the distribution, and bluebird bio will be responsible for liabilities associated with other employees, including employees retained by bluebird bio.

The Audit Committee has reviewed our audited financial statements for the fiscal year ended December 31, 2023 and has discussed these statements with management and representatives of Ernst & Young LLP, our independent registered public accounting firm. Our management is responsible for the preparation of our financial statements and for maintaining an adequate system of disclosure controls and procedures and internal control over financial reporting for that purpose. Ernst & Young LLP is responsible for performing an audit of 2seventy bio’s financial statements in accordance with the standards of the Public Company Accounting Oversight Board ("PCAOB") and issuing a report thereon. The Audit Committee is responsible for providing independent, objective oversight of our accounting functions and internal controls.

In connection with these responsibilities, the Audit Committee reviewed and discussed with management and the independent registered public accounting firm the audited consolidated and combined financial statements of 2seventy bio for the fiscal year ended December 31, 2023. The Audit Committee also discussed with the independent registered public accounting firm the matters required to be discussed pursuant to PCAOB and SEC rules. In addition, the Audit Committee received written disclosures and the letter from Ernst & Young LLP as required by the applicable requirements of the PCAOB regarding their communication with the Audit Committee concerning independence and has discussed with Ernst & Young LLP their independence.

Based on its discussions with management and our independent registered public accounting firm, and its review of the representations and information provided by management and our independent registered public accounting firm, the Audit Committee recommended to the Board that the audited financial statements be included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2023, for filing with the SEC.

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(1) This Section is not “soliciting material,” is not deemed filed with the SEC and is not to be incorporated by reference in any filing by us under the Securities Act of 1933, as amended, or the Exchange Act, whether made before or after the date hereof and irrespective of any general incorporation language in any such filing.

Ernst & Young LLP, independent registered public accounting firm, has been selected by the Audit Committee as auditors for 2seventy bio for the fiscal year ending December 31, 2024. Ernst & Young LLP has served as our independent registered public accounting firm since 2021. A representative of Ernst & Young LLP is expected to be present at the Annual Meeting with the opportunity to make a statement if he or she desires and to respond to appropriate questions.

Our organizational documents do not require that the stockholders ratify the selection of Ernst & Young LLP as our independent registered public accounting firm. 2seventy bio requests such ratification as a matter of good corporate practice. The selection of Ernst & Young LLP as our independent registered public accounting firm will be ratified if the votes cast FOR exceed the votes cast AGAINST the proposal. Brokers, bankers and other nominees have discretionary voting power on this routine matter. Abstentions and broker non-votes will have no effect on the ratification. If the stockholders do not ratify the selection, the Audit Committee will reconsider whether to retain Ernst & Young LLP, but still may retain this firm. Even if the selection is ratified, the Audit Committee, in its discretion, may change the appointment at any time during the year if it determines that such a change would be in our best interests and those of our stockholders.

The Audit Committee, or a designated member thereof, pre-approves each audit and non-audit service rendered by Ernst & Young LLP to us consistent with our Audit and Non-Audit Services Pre-Approval Policy.

Independent Registered Public Accounting Firm Fees

The following is a summary and description of fees incurred by Ernst & Young LLP for the fiscal years ended December 31, 2022 and 2023:

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Stockholder Proposals and Director Nominations

Stockholders who wish to present proposals for inclusion in our proxy materials for the 2025 Annual Meeting of Stockholders may do so by following the procedures prescribed in Rule 14a-8 under the Exchange Act and in our bylaws. Rule 14a-8 proposals must be delivered by mail to 2seventy bio, Inc., 60 Binney Street, Cambridge, Massachusetts 02142, Attention: Corporate Secretary. Our Corporate Secretary must receive stockholder proposals intended to be included in our proxy statement and form of proxy relating to our 2025 Annual Meeting made under Rule 14a-8 by December 26, 2024.

If a stockholder wishes to propose a nomination of persons for election to our Board or present a proposal at an annual meeting but does not wish to have the proposal considered for inclusion in our proxy statement and proxy card, our bylaws establish an advance notice procedure for such nominations and proposals. Stockholders at an annual meeting may only consider proposals or nominations specified in the notice of meeting or brought before the meeting by or at the direction of the Board or by a stockholder of record on the record date for the meeting, who is entitled to vote at the meeting and who has delivered timely notice in proper form to our Corporate Secretary of the stockholder’s intention to bring such business before the meeting.

Any proposal of business or nomination should be mailed to: 2seventy bio, Inc., 60 Binney Street, Cambridge, Massachusetts 02142, Attention: Corporate Secretary.

Any stockholder recommendation for a director nominee must be submitted to 2seventy bio not less than 120 calendar days prior to the date on which our proxy statement was released to stockholders in connection with the previous year’s annual meeting. To comply with the universal proxy rules, stockholders who intend to solicit proxies for the 2025 Annual Meeting of Stockholders in support of director nominees other than the Company’s nominees must provide notice that sets forth the information required by Rule 14a-19 under the Exchange Act no later than April 11, 2025.

Other Stockholder Communications

Generally, stockholders who have questions or concerns should contact our Investor Relations department at investor@2seventybio.com. However, stockholders who wish to communicate directly with our Board as a whole may send written communication by mail to 2seventy bio, Inc., 60 Binney Street, Cambridge, Massachusetts 02142, Attention: Chair of the Board. For a communication directed to an individual director in his or her capacity as a member of the Board, stockholders may send such communication to 2seventy bio, Inc., 60 Binney Street, Cambridge, Massachusetts 02142, Attention: [Name of Individual Director]. All such communications will be opened by our Corporate Secretary for the sole purpose of determining whether the contents represent a message to our directors. Any contents that are not in the nature of advertising, promotions of a product or service, or patently offensive material will be forwarded promptly to the addressee(s).

You should rely on the information contained in this document to vote your shares at the Annual Meeting. 2seventy bio has not authorized anyone to provide you with information that is different from what is contained in this document. This document is dated April 25, 2024. You should not assume that the information contained in this document is accurate as of any date other than that date, and the mailing of this document to stockholders at any time after that date does not create an implication to the contrary. This proxy statement does not constitute a solicitation of a proxy in any jurisdiction where, or to or from any person to whom, it is unlawful to make such proxy solicitations in such jurisdiction.