SEC Form DEFM14A filed by Vigil Neuroscience Inc.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

Filed by the Registrant ☒

Filed by a Party other than the Registrant ☐

Check the appropriate box:

VIGIL NEUROSCIENCE, INC.

(Name of Registrant as Specified in Its Charter)

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

Payment of Filing Fee (Check the appropriate box):

VIGIL NEUROSCIENCE, INC.

VIGIL NEUROSCIENCE, INC.

100 FORGE ROAD, SUITE 700

WATERTOWN, MA 02472

June 30, 2025

Dear Stockholders,

We cordially invite you to attend a special meeting of stockholders of Vigil Neuroscience, Inc., a Delaware corporation (the “Company”), to be held online on August 4, 2025, at 8:30 a.m., Eastern Time (the “Special Meeting”). You will be able to attend the Special Meeting by registering at www.virtualshareholdermeeting.com/VIGL2025SM and entering your 16-digit control number included in your proxy materials. You will not be able to attend the Special Meeting in person. For purposes of attendance at the Special Meeting, all references in the accompanying proxy statement to “present” or “in person” shall mean virtually present at the Special Meeting.

On May 21, 2025, the Company entered into an Agreement and Plan of Merger (the “Merger Agreement”) with Sanofi, a French société anonyme (“Parent”), and Vesper Acquisition Sub Inc., a Delaware corporation and a wholly owned subsidiary of Parent (“Merger Sub”), pursuant to which, on the terms and subject to the conditions set forth in the Merger Agreement, Merger Sub will be merged with and into the Company (the “Merger”), with the Company continuing as the surviving corporation in the Merger and as a wholly owned subsidiary of Parent.

If the Merger is completed, you will be entitled to receive, for each issued and outstanding share of common stock, par value $0.0001, of the Company (the “Company common stock”) that you own immediately prior to the effective time of the Merger (the “Effective Time”), (i) $8.00 in cash, without interest, less any applicable withholding taxes, plus (ii) one contractual contingent value right (“CVR”) representing the right to receive a contingent payment of $2.00, net to the holder in cash and without interest thereon and less any applicable withholding taxes, upon the terms and conditional upon the achievement of the Milestone (as defined below) set forth in the CVR Agreement (as defined below) ((i) and (ii) collectively, the “Merger Consideration”).

At or prior to the Effective Time, pursuant to the Merger Agreement, Parent will enter into a Contingent Value Rights Agreement with a rights agent (the “Rights Agent”), in substantially the form attached to the Merger Agreement (the “CVR Agreement”). Each CVR will represent the right to receive a contingent payment of $2.00, net to the holder in cash and without interest thereon, payable to the Rights Agent for the benefit of the holders of CVRs, if the First Commercial Sale (as defined in the CVR Agreement) of the Company’s clinical candidate VG-3927 (the “Milestone”) occurs between the Effective Time and December 31, 2035.

By unanimous vote, the Board of Directors of the Company (the “Board of Directors”), at a meeting held on May 21, 2025, (i) determined that the Merger Agreement and the Transactions (as defined below), including the Merger, are advisable and fair to, and in the best interest of, the Company and its stockholders, (ii) approved the execution, delivery and performance by the Company of the Merger Agreement and the consummation by the Company of the Transactions, including the Merger, (iii) directed that the Merger Agreement be submitted to the stockholders of the Company for their adoption at the Special Meeting, (iv) resolved to recommend that the

stockholders of the Company adopt the Merger Agreement and approve the Merger (the “Transaction Proposal”) and (v) approved and declared advisable the Voting and Support Agreements (as defined below) and the transactions contemplated thereby. “Transactions” shall herein refer to (i) the execution and delivery of the Merger Agreement, the CVR Agreement and the Voting and Support Agreements and (ii) all of the transactions contemplated thereby, including the Merger.

At the Special Meeting, stockholders will also be asked to vote on a proposal to adjourn the Special Meeting, from time to time, if necessary or appropriate, to solicit additional votes for the approval of the proposal to adopt the Merger Agreement if there are insufficient votes at the time of the Special Meeting to adopt the Merger Agreement (the “Adjournment Proposal”).

In connection with the Merger Agreement, Parent also entered into voting and support agreements (the “Voting and Support Agreements”) with Ivana Magovčević-Liebisch, the Company’s chief executive officer, Bruce Booth, Atlas Venture Fund XII, L.P. and Atlas Venture Opportunity Fund I, L.P. (the “Supporting Stockholders”) under which the Supporting Stockholders agreed, among other things, to vote, or cause to be voted, all of the shares of Company common stock beneficially owned by such Supporting Stockholder in favor of the adoption of the Merger Agreement. As of the record date, the Supporting Stockholders collectively beneficially owned approximately 16.54% of the total voting power of the outstanding shares of Company common stock.

Approval of the Transaction Proposal requires the affirmative vote of holders of a majority of the outstanding shares of Company common stock entitled to vote on the Transaction Proposal. Approval of the Adjournment Proposal requires the affirmative vote of holders of a majority of the shares of Company common stock properly cast for and against the Adjournment Proposal at the Special Meeting and entitled to vote on the Adjournment Proposal. Holders of shares of the Company’s Series A Non-Voting Convertible Preferred Stock, par value $0.0001 per share (the “Company preferred stock”), do not have the right to vote their shares of Company preferred stock on the Transaction Proposal or the Adjournment Proposal.

The Board of Directors of the Company unanimously recommends that you vote “FOR” approval of the Transaction Proposal and “FOR” approval of the Adjournment Proposal.

Your vote is very important. Whether or not you plan to attend the Special Meeting, please complete, date, sign and return, as promptly as possible, the accompanying proxy card in the envelope provided, or submit your proxy by telephone or the Internet. If you attend the Special Meeting and vote via the virtual meeting website, your vote via the virtual meeting website will revoke any proxy previously submitted.

If your shares of Company common stock are held in “street name” by your bank, brokerage firm or other nominee, your bank, brokerage firm or other nominee will be unable to vote your shares of Company common stock at the Special Meeting without instructions from you. You should instruct your bank, brokerage firm or other nominee to vote your shares of Company common stock in accordance with the procedures provided by your bank, brokerage firm or other nominee.

The accompanying proxy statement provides you with detailed information about the Special Meeting, the Merger Agreement and the Merger. A copy of the Merger Agreement is attached as Annex A to the proxy statement. We encourage you to read the entire proxy statement and its annexes, including the Merger Agreement, carefully. You may also obtain additional information about the Company from documents we have filed with the U.S. Securities and Exchange Commission (the “SEC”).

Stockholders or beneficial owners who continuously hold their shares of Company common stock through the Effective Time, who do not vote in favor of nor consent to the Transaction Proposal, who properly demand in writing an appraisal of their shares delivered to the Company prior to the taking of the vote on the Transaction Proposal and who comply with, and do not validly withdraw their demands or otherwise lose their appraisal rights under, Section 262 of the Delaware General Corporation Law as in effect at the time of the parties’ entry into the Merger Agreement (“Section 262”), the provisions of which are summarized in the section entitled “Appraisal

Rights” in the accompanying proxy statement and a copy of which may be accessed without subscription or cost at the following publicly available website: https://delcode.delaware.gov/title8/c001/sc09/index.html#262, will be entitled to appraisal rights to receive, in cash, the fair value of their shares of Company common stock as determined by the Delaware Court of Chancery, subject to the terms of Section 262.

If your shares of Company common stock are registered directly in your name through our transfer agent, or you have stock certificates registered in your name, and you need additional copies of the accompanying proxy statement or the accompanying proxy card or voting instructions, please contact our proxy tabulator by email or by phone:

Email: [email protected]

Stockholders Call (toll-free): (877) 869-0171

Banks and Brokers Call: (212) 297-0720

If your shares of Company common stock are held in the name of a bank, broker, or other nominee, you will receive instructions from your bank, broker, or other nominee of record if you need additional copies of the accompanying proxy statement or the accompanying proxy card or voting instructions.

Thank you in advance for your support and prompt consideration of this matter.

NEITHER THE SEC NOR ANY STATE SECURITIES COMMISSION HAS APPROVED OR DISAPPROVED THE MERGER, PASSED UPON THE MERITS OR FAIRNESS OF THE MERGER AGREEMENT OR THE TRANSACTIONS CONTEMPLATED BY THE MERGER AGREEMENT OR PASSED UPON THE ADEQUACY OR ACCURACY OF THE INFORMATION CONTAINED IN THE ACCOMPANYING PROXY STATEMENT. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.

The accompanying proxy statement is dated June 30, 2025 and, together with the accompanying form of proxy card, is first being mailed on or about June 30, 2025.

VIGIL NEUROSCIENCE, INC.

100 FORGE ROAD, SUITE 700

WATERTOWN, MA 02472

NOTICE OF SPECIAL MEETING OF STOCKHOLDERS

To Be Held on August 4, 2025

Notice is hereby given that a special meeting of the stockholders of Vigil Neuroscience, Inc., a Delaware corporation (the “Company”), will be held online on August 4, 2025 at 8:30 a.m., Eastern Time (the “Special Meeting”). You will be able to attend the Special Meeting virtually by registering at www.virtualshareholdermeeting.com/VIGL2025SM and entering your 16-digit control number included in your proxy materials. You will not be able to attend the Special Meeting in person. For purposes of attendance at the Special Meeting, all references in this proxy statement to “present” or “in person” shall mean virtually present at the Special Meeting. The Special Meeting will be held for the following purposes:

The Merger Agreement and the Transactions (as defined below), including the Merger, are described more fully in the accompanying proxy statement, and we urge you to read it carefully and in its entirety.

By unanimous vote, the Board of Directors of the Company (the “Board of Directors”), at a meeting held on May 21, 2025, (i) determined that the Merger Agreement and the Transactions, including the Merger, are advisable and fair to, and in the best interest of, the Company and its stockholders, (ii) approved the execution, delivery and performance by the Company of the Merger Agreement and the consummation by the Company of the Transactions, including the Merger, (iii) directed that the Merger Agreement be submitted to the stockholders of the Company for their adoption at the Special Meeting, (iv) resolved to recommend that the stockholders of the Company adopt the Merger Agreement and approve the Merger and (v) approved and declared advisable the voting and support agreements (the “Voting and Support Agreements”) with Ivana Magovčević-Liebisch, the Company’s chief executive officer, Bruce Booth, Atlas Venture Fund XII, L.P. and Atlas Venture Opportunity Fund I, L.P. and the transactions contemplated thereby. “Transactions” shall herein refer to (i) the execution and delivery of the Merger Agreement, the Contingent Value Rights Agreement and the Voting and Support Agreements and (ii) all of the transactions contemplated thereby, including the Merger.

Approval of the Transaction Proposal requires the affirmative vote of holders of a majority of the outstanding shares of common stock, par value $0.0001, of the Company (the “Company common stock”) entitled to vote on the Transaction Proposal. Approval of the Adjournment Proposal requires the affirmative vote of holders of a majority of the shares of Company common stock properly cast for and against the Adjournment Proposal at the Special Meeting and entitled to vote on the Adjournment Proposal. Holders of shares of the Company’s Series A Non-Voting Convertible Preferred Stock, par value $0.0001 per share (the “Company preferred stock”), do not have the right to vote their shares of Company preferred stock on the Transaction Proposal or the Adjournment Proposal.

Your vote is very important, regardless of the number of shares of Company common stock you own. The Merger cannot be completed unless the Merger Agreement is adopted by the affirmative vote of holders of a

majority of the outstanding shares of Company common stock entitled to vote on the Transaction Proposal. Even if you plan to attend the Special Meeting, we request that you complete, sign, date and return, as promptly as possible, the accompanying proxy card in the accompanying prepaid reply envelope or submit your proxy by telephone or the Internet prior to the Special Meeting to ensure that your shares of Company common stock will be represented at the Special Meeting if you are unable to attend.

The Board of Directors has fixed the close of business on June 26, 2025 as the record date (the “record date”) for determining the stockholders entitled to receive notice of, and to vote at, the Special Meeting and any adjournments or postponements thereof. Only stockholders of record of the shares of Company common stock at the close of business on the record date are entitled to receive notice of, and to vote at, the Special Meeting and at any adjournment or postponements thereof. A complete list of our stockholders of record entitled to vote at the Special Meeting will be available for a period of at least ten (10) days prior to the date of the Special Meeting for any purpose germane to the Special Meeting for inspection (i) on a reasonably accessible electronic network, provided that the information required to gain access to such list is included with the notice of the Special Meeting or (ii) at our principal operating offices during ordinary business hours of the Company. The list of our stockholders of record entitled to vote at the Special Meeting will also be available electronically during the Special Meeting for inspection by any stockholder present at the Special Meeting for any purpose germane to the Special Meeting.

Only stockholders of record, their duly authorized proxy holders, beneficial stockholders with proof of ownership and our guests may attend the Special Meeting.

Stockholders or beneficial owners who continuously hold their shares of Company common stock through the effective time of the Merger, who do not vote in favor of nor consent to the Transaction Proposal, who properly demand in writing an appraisal of their shares delivered to the Company prior to the taking of the vote on the Transaction Proposal and who comply with, and do not validly withdraw their demands or otherwise lose their appraisal rights under, Section 262 of the Delaware General Corporation Law as in effect at the time of the parties’ entry into the Merger Agreement (“Section 262”), the provisions of which are summarized in the section entitled “Appraisal Rights” in the accompanying proxy statement and a copy of which may be accessed without subscription or cost at the following publicly available website: https://delcode.delaware.gov/title8/c001/sc09/index.html#262, will be entitled to appraisal rights to receive, in cash, the fair value of their shares of Company common stock as determined by the Delaware Court of Chancery, subject to the terms of Section 262.

WHETHER OR NOT YOU PLAN TO ATTEND THE SPECIAL MEETING, PLEASE COMPLETE, DATE, SIGN AND RETURN, AS PROMPTLY AS POSSIBLE, THE ACCOMPANYING PROXY CARD IN THE ACCOMPANYING PREPAID REPLY ENVELOPE, OR SUBMIT YOUR PROXY BY TELEPHONE OR THE INTERNET. IF YOU WILL ATTEND THE SPECIAL MEETING AND VOTE VIA THE VIRTUAL MEETING WEBSITE, YOUR VOTE VIA THE VIRTUAL MEETING WEBSITE WILL REVOKE ANY PROXY PREVIOUSLY SUBMITTED.

Watertown, Massachusetts

Dated: June 30, 2025

TABLE OF CONTENTS

i

ii

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

QUESTIONS AND ANSWERS ABOUT THE SPECIAL MEETING AND THE MERGER

The following questions and answers are intended to address briefly some commonly asked questions regarding the Merger Agreement, the Merger and the Special Meeting. These questions and answers may not address all questions that may be important to you as a stockholder of the Company. Please refer to the “Summary” beginning on page 1 and the more detailed information contained elsewhere in this proxy statement, the annexes to this proxy statement and the documents referred to or incorporated by reference in this proxy statement, which you should read carefully and in their entirety. You may obtain the information incorporated by reference in this proxy statement without charge by following the instructions under “Where You Can Find More Information” beginning on page 118.

Q. Why am I receiving this proxy statement and proxy card or voting instruction form?

A. You are receiving this proxy statement and proxy card or voting instruction form in connection with the solicitation of proxies by the Board of Directors of the Company (the “Board of Directors”) for use at the Special Meeting (as defined below) because you have been identified as a holder of Company common stock as of the close of business on June 26, 2025, the record date for the Special Meeting. This proxy statement describes matters on which we urge you to vote and is intended to assist you in deciding how to vote your shares of Company common stock with respect to such matters.

Q. What is a proxy?

A. A proxy is your legal designation of another person, referred to as a “proxy,” to vote your shares of Company common stock. The written document describing the matters to be considered and voted on at the Special Meeting is called a “proxy statement.” The document used to designate a proxy to vote your shares of Company common stock is called a “proxy card.”

Q. When and where is the Special Meeting?

A. The Special Meeting of stockholders of the Company will be held online in a virtual format at www.virtualshareholdermeeting.com/VIGL2025SM, on August 4, 2025, at 8:30 a.m., Eastern Time (the “Special Meeting”).

Q. What am I being asked to vote on at the Special Meeting?

A. You are being asked to consider and vote on:

Q. What is the proposed transaction and what effects will it have on the Company?

A. The proposed transaction is the acquisition of the Company by Parent through the merger of the Merger Sub with and into the Company, with the Company continuing as the surviving corporation in the Merger (the “Surviving Corporation”) and as a wholly owned subsidiary of Parent. If the Transaction Proposal is approved by

18

the affirmative vote of holders of a majority of the issued and outstanding shares of Company common stock entitled to vote thereon as of the close of business on June 26, 2025 and the other closing conditions under the Merger Agreement are satisfied or waived, upon Closing, Merger Sub will be merged with and into the Company, with the Company continuing as the Surviving Corporation and as a wholly owned subsidiary of Parent. The Merger Agreement, which governs the terms and conditions of the Merger, is attached as Annex A to this proxy statement. Your vote is required to approve the Merger Agreement.

Upon completion of the Merger, the shares of Company common stock currently listed on the Nasdaq Stock Market LLC (“Nasdaq”) will cease to be listed on the Nasdaq and will subsequently be deregistered under the Securities Exchange Act of 1934, as amended (the “Exchange Act”). The Company will also no longer file periodic reports with the U.S. Securities and Exchange Commission (the “SEC”) on account of the Company common stock.

Q. What will holders of Company common stock receive if the Merger is completed?

A. Upon completion of the Merger, you will be entitled to receive, for each share of Company common stock that you own immediately prior to the effective time of the Merger (the “Effective Time”),(i) $8.00 in cash, without interest, less any applicable withholding taxes, plus (ii) one contractual contingent value right (“CVR”) representing the right to receive a contingent payment of $2.00 net to the holder in cash and without interest thereon and less any applicable withholding taxes (the amounts referred to in clauses (i) and (ii), collectively, the “Merger Consideration”), upon the terms and conditional upon the achievement of the Milestone (as defined below), unless you have properly exercised and not failed to perfect, waived, withdrawn or otherwise lost your right to appraisal in accordance with Section 262 of the Delaware General Corporation Law (“DGCL”) as in effect at the time of the parties’ entry into the Merger Agreement (“Section 262”). For additional information, see the section titled “The Merger Agreement—Treatment of Company Common Stock and Company Preferred Stock” beginning on page 81 of this proxy statement.

Q. What will holders of Company preferred stock receive if the Merger is completed?

A. Upon completion of the Merger, each share of the Company’s Series A Non-Voting Convertible Preferred Stock, par value $0.0001 per share (the “Company preferred stock”), and each share of Company common stock issued upon conversion of any share of Company preferred stock prior to the Effective Time (if any), in each case issued and outstanding immediately prior to the Effective Time and held by Parent or any other direct or indirect wholly owned subsidiary of Parent shall automatically be converted into such number of shares of common stock, $0.0001 par value per share, of the Surviving Corporation (“Surviving Corporation Stock”), such that each such holder of such shares shall own the same percentage of the outstanding shares of Surviving Corporation Stock immediately following the Effective Time as such holder owned of the Fully Converted Share Count (as defined in the Merger Agreement) (on an as-converted to Company common stock basis, without regard to any conversion limitations) immediately prior to the Effective Time. Parent holds all issued and outstanding Company preferred stock as of May 21, 2025.

Q. What will holders of the Company’s equity awards receive if the Merger is completed?

A. As of the Effective Time, by virtue of the Merger and without any further action on the part of the holder of any outstanding option to purchase a share of Company common stock (a “Company Option”), Parent, Merger Sub, or the Company, each Company Option will be treated as follows:

19

As of the Effective Time, by virtue of the Merger and without any further action on the part of the holder of any restricted stock unit award with respect to shares of Company common stock (a “Company RSU”), Parent, Merger Sub, or the Company, each outstanding Company RSU will be treated as follows:

For additional information, see the section titled “The Merger Agreement—Treatment of Company Equity Awards and the Company ESPP” beginning on page 82 of this proxy statement.

Q. How does the Merger Consideration compare to the market price of the Company common stock as of a recent trading date?

A. The Merger Consideration represents a premium of approximately 333% over the closing price of the Company common stock on Nasdaq of $2.31 on May 21, 2025, the last trading day before the date on which the Company publicly announced that it had entered into the Merger Agreement, and a premium of approximately 350% over the 30-day volume-weighted average price of the Company common stock as of May 21, 2025. On June 27, 2025, the last practicable day before the printing of this proxy statement, the closing price of the Company common stock on Nasdaq was $7.95 per share. You are encouraged to obtain current market quotations for the Company common stock.

Q. How does the Board of Directors recommend that I vote?

A. The Board of Directors unanimously recommends that you vote “FOR” approval of the Transaction Proposal and “FOR” approval of the Adjournment Proposal.

20

Q. When do you expect the Merger to be completed?

A. We are working towards completing the Merger as soon as possible. Assuming timely receipt of required regulatory approvals and satisfaction of other closing conditions, including approval by our stockholders of the Transaction Proposal, we anticipate that the Merger will be completed in the third quarter of 2025. However, it is possible, including as a result of factors outside the control of the Company and Parent, that the Merger will be consummated at a later time or not at all.

Q. What happens if the Merger is not completed?

A. If the Merger Agreement is not adopted by the holders of a majority of the issued and outstanding Company common stock entitled to vote on the Transaction Proposal or if the Merger is not completed for any other reason, the stockholders of the Company will not receive any payment for their shares of Company common stock in connection with the Merger. Instead, the Company will remain an independent public company, the Company common stock will continue to be listed and traded on Nasdaq and the Company will continue to file periodic reports with the SEC.

Under specified circumstances in the Merger Agreement, the Company may be required to disburse or pay a termination fee with respect to the termination of the Merger Agreement, as described under the section titled “The Merger Agreement—Termination Fee” beginning on page 101 of this proxy statement.

Q. What conditions must be satisfied to complete the Merger?

A. Consummation of the Merger is subject to the satisfaction or waiver of certain customary conditions, including: (i) the adoption and approval of the Merger Agreement by holders of a majority of the Company common stock issued and outstanding and entitled to vote on the Transaction Proposal at the Special Meeting; (ii) receipt of regulatory approval under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended (the “HSR Act”) and other applicable antitrust laws; (iii) the absence of any legal prohibitions; (iv) the accuracy of representations and warranties of each party and the performance in all material respects by each party with its respective covenants and obligations under the Merger Agreement; (v) the satisfaction of the Amgen Closing Condition (as defined below); and (vi) the absence of any Material Adverse Effect (as defined in the Merger Agreement) that is continuing. For additional information, see the section titled “The Merger Agreement—Conditions to the Merger” beginning on page 97 of this proxy statement.

Q. What are the material U.S. federal income tax consequences of the Merger?

A. The receipt of cash and CVRs by a U.S. holder (as defined under the section of this proxy statement titled “The Merger—Material U.S. Federal Income Tax Consequences of the Merger”) pursuant to the Merger will be a taxable transaction to U.S. holders. The amount of gain or loss a U.S. holder will recognize, and the timing of such gain or loss, depends on the U.S. federal income tax treatment of the CVRs, with respect to which there is a significant amount of uncertainty.

Non-U.S. holders (as defined under the section of this proxy statement titled “The Merger—Material U.S. Federal Income Tax Consequences of the Merger”) generally will not be subject to U.S. federal income tax with respect to the receipt of cash and CVRs in the Merger unless such Non-U.S. holder has certain connections to the United States, but may be subject to the backup withholding rules described below unless the Non-U.S. holder complies with certain certification procedures or otherwise establishes a valid exemption from backup withholding.

Please carefully review the information under the section titled “The Merger—Material U.S. Federal Income Tax Consequences of the Merger” beginning on page 70 of this proxy statement for a more detailed discussion of the U.S. federal income tax consequences of the Merger.

21

Q. Do any of the Company’s directors or officers have interests in the Merger that may differ from or be in addition to my interests as a stockholder?

A. In considering the recommendation of the Board of Directors that Company stockholders vote in favor of the Transaction Proposal, the Company stockholders should be aware that executive officers and directors of the Company may have certain interests in the Merger that are different from, or in addition to, the interests of the Company’s stockholders generally. The members of the Board of Directors were aware of and considered these potential interests, among other matters, in reaching the determination to approve and adopt the Merger Agreement and other related agreements and recommend to Company stockholders that they vote in favor of the Transaction Proposal as more fully discussed in the section titled “The Merger—Recommendation of the Board of Directors and Reasons for the Merger” beginning on page 51 of this proxy statement.

Q. What vote is required for the Company’s stockholders to approve the Transaction Proposal?

A. The adoption of the Transaction Proposal requires the affirmative vote of holders of a majority of the issued and outstanding shares of Company common stock entitled to vote on the Transaction Proposal.

Accordingly, abstentions will have the same effect as a vote “AGAINST” the Transaction Proposal. If you fail to submit a proxy or to vote, your shares of Company common stock will be treated as a vote “AGAINST” the proposal to approve the Transaction Proposal. The Transaction Proposal is a non-routine matter. As none of the proposals to be voted on at the Special Meeting are routine matters, the Company does not expect any broker non-votes with respect to the Transaction Proposal. See “—If my broker holds my shares in ‘street name,’ will my broker vote my shares for me?” below.

Q. What vote is required for the Company’s stockholders to approve the Adjournment Proposal?

A. Approval of the Adjournment Proposal requires the affirmative vote of holders of a majority of the shares of Company common stock properly cast for and against the Adjournment Proposal at the Special Meeting and entitled to vote on the Adjournment Proposal.

Accordingly, abstentions will have no effect on the outcome of the Adjournment Proposal and will not count as either a vote “FOR” or “AGAINST” the Adjournment Proposal. If you fail to submit a proxy or to vote, your failure to submit a proxy or to vote will have no impact on the Adjournment Proposal. The Adjournment Proposal is a non-routine matter. As none of the proposals to be voted on at the Special Meeting are routine matters, the Company does not expect any broker non-votes with respect to the Adjournment Proposal. See “—If my broker holds my shares in ‘street name,’ will my broker vote my shares for me?” below.

Q. Who can vote at the Special Meeting?

A. Only stockholders of record of shares of Company common stock at the close of business on June 26, 2025, (the “record date”) are entitled to receive notice of, and to vote at, the Special Meeting and at any adjournment or postponement thereof. On the record date, there were 47,686,561 shares of Company common stock issued and outstanding and entitled to vote at the Special Meeting, held by seven stockholders of record. Holders of Company preferred stock do not have the right to vote their shares of Company preferred stock on the Transaction Proposal and the Adjournment Proposal.

Registered Stockholders. If shares of Company common stock are registered directly in your name with our transfer agent, you are considered the stockholder of record with respect to those shares. As the stockholder of record, you have the right to grant your voting proxy directly to the individuals listed on the proxy card or vote on your own behalf at our virtual Special Meeting. Throughout this proxy statement, we refer to these registered stockholders as “stockholders of record.” If you are a stockholder of record, you may vote via the virtual meeting website at the Special Meeting, by mail or over the Internet. Whether or not you plan to attend the Special

22

Meeting, we urge you to vote by proxy to ensure your vote is counted. You may still attend the Special Meeting and vote via the virtual meeting website if you have already voted by proxy. Voting via the virtual meeting website at the Special Meeting will revoke your proxy.

Street Name Stockholders. If shares of Company common stock are held on your behalf in a brokerage account or by a bank or other nominee, you are considered to be the beneficial owner of shares that are held in “street name,” and the proxy materials were forwarded to you by your broker or nominee, who is considered the stockholder of record with respect to those shares. As the beneficial owner, you have the right to direct your broker, bank or other nominee as to how to vote your shares. Beneficial owners are also invited to attend our virtual Special Meeting. However, since a beneficial owner is not the stockholder of record, you may not vote your shares of the Company common stock on your own behalf at the Special Meeting unless you follow your broker’s procedures for obtaining a legal proxy. Note you should also be receiving a voting instruction form for you to use from your broker. Throughout this proxy statement, we refer to stockholders who hold their shares through a broker, bank or other nominee as “street name stockholders.”

Q. If my broker holds my shares in “street name,” will my broker vote my shares for me?

A. All brokers registered as members with The New York Stock Exchange (“NYSE”) are subject to NYSE rules and, accordingly, NYSE rules apply to the voting of all shares held in a brokerage account, including shares of a company listed on Nasdaq. Under the rules of NYSE, banks, brokerage firms or other nominees who hold shares in “street name” for customers have the authority to vote on “routine” proposals when they have not received instructions from beneficial owners. However, banks, brokerage firms or other nominees are precluded from exercising their voting discretion with respect to approving non-routine matters, such as the Transaction Proposal and the Adjournment Proposal, and, as a result, absent specific instructions from the beneficial owner of such shares of Company common stock, banks, brokerage firms or other nominees are not empowered to vote those shares of Company common stock on non-routine matters, which we refer to generally as “broker non-votes.” Because none of the proposals to be voted on at the Special Meeting are routine matters for which brokers may have discretionary authority to vote, the Company does not expect any broker non-votes at the Special Meeting.

Q. How many votes do I have?

A. Each holder of Company common stock is entitled to one vote on all matters properly brought before the Special Meeting for each share of Company common stock that such holder owned at the close of business on of the record date of June 26, 2025. At the close of business on the record date, there were a total of 47,686,561 shares of Company common stock issued and outstanding and entitled to vote at the Special Meeting, held by seven holders of record.

Q. What is the quorum requirement?

A. Our Amended and Restated Bylaws (“bylaws”) provide that the presence, in person, by remote communication, if applicable, or by proxy duly authorized, of the holders of a majority of the outstanding shares of Company common stock entitled to vote at the Special Meeting will constitute a quorum for the transaction of business at the Special Meeting. Holders of Company preferred stock are not entitled to vote such shares at the Special Meeting and such shares will not be counted for purposes of determining whether a quorum is present.

Abstentions and broker non-votes will be included in the calculation of the number of shares of Company common stock present at the Special Meeting for purposes of determining whether a quorum has been achieved. Because none of the proposals to be voted on at the Special Meeting are routine matters for which brokers may have discretionary authority to vote, the Company does not expect any broker non-votes at the Special Meeting. If a quorum is not present, then under the bylaws, either (i) the holders of Company common stock representing a majority of the voting power present at the Special Meeting, or (ii) the presiding officer of the Special Meeting, may adjourn the meeting, and the meeting may be held as adjourned without further notice other than an

23

announcement at the meeting at which the adjournment or postponement is taken of the hour, date and place, if any, to which the meeting is adjourned and the means of remote communications, if any, by which the holders of Company common stock and proxy holders may be deemed to be present and vote at such adjourned meeting. However, the bylaws provide that if any such adjournment is for more than 30 days, or if after an adjournment a new record date for determining stockholders entitled to vote is fixed for the adjourned meeting, a notice of the adjourned meeting and the means of remote communications, if any, by which stockholders and proxyholders may be deemed to be present in person and vote at such adjourned meeting, shall be given to each stockholder of record entitled to vote at the adjourned meeting.

Q. How do I vote?

A. Stockholder of Record. If you are a stockholder of record, there are several ways for you to vote your shares.

If the Special Meeting is adjourned or postponed, the deadlines above may be extended.

Beneficial Owner. The voting deadlines and availability of telephone and Internet voting for beneficial owners of shares held in “street name” will depend on the voting processes of the organization that holds your shares. Therefore, we urge you to carefully review and follow the voting instruction card and any other materials that you receive from that organization. If you hold your shares of Company common stock in multiple accounts, you should vote your shares as described in each set of proxy materials you receive.

By Proxy. If you will not be attending the Special Meeting, you may vote by proxy. You can vote by proxy over the Internet by following the instructions provided in the accompanying proxy card. Proxies submitted by mail must be received before the start of the Special Meeting.

If you submit a proxy without giving voting instructions, your shares will be voted in the manner recommended by the Board of Directors on all matters presented in this proxy statement, and as the persons named as proxies in the proxy card may determine in their discretion with respect to any other matters properly presented at the Special 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.

Q. How can I change or revoke my proxy?

A. You may revoke your proxy by (i) following the voting instruction form and entering a new vote by mail that we receive before the start of the Special Meeting or over the Internet or by telephone by the cutoff time of 11:59 p.m. Eastern Time on the business day immediately prior to the date of the Special Meeting, (ii) attending

24

and voting at the Special Meeting via the virtual meeting website (although attendance at the Special Meeting will not in and of itself revoke a proxy), or (iii) by filing an instrument in writing revoking the proxy or another duly executed proxy bearing a later date with our corporate secretary. Any written notice of revocation or subsequent proxy card must be received by our corporate secretary by 5:00 p.m. Eastern Time on the business day immediately prior to the date of the Special 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 Vigil Neuroscience, Inc., 100 Forge Road, Suite 700, Watertown, MA 02472, 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.

Q. If a stockholder gives a proxy, how are the shares of Company common stock voted?

A. Regardless of the method you choose to submit your proxy, the individuals named on the accompanying proxy card will vote your shares of Company common stock in the way that you indicate. When completing the Internet or telephone processes or the proxy card, you may specify whether your shares of Company common stock should be voted for or against or to abstain from voting on all, some or none of the specific items of business to come before the Special Meeting.

If you own shares of Company common stock that are registered in your own name and return a signed proxy card or submit a proxy via the Internet or by telephone, but do not indicate how you wish your shares of Company common stock to be voted, the shares of Company common stock represented by your properly signed proxy will be voted “FOR” approval of the Transaction Proposal and “FOR” approval of the Adjournment Proposal.

Q. How are votes counted?

A. For the Transaction Proposal, you may vote “FOR,” “AGAINST” or “ABSTAIN.” Abstentions will have the same effect as if you voted “AGAINST” approval of the Transaction Proposal.

For the Adjournment Proposal, you may vote “FOR,” “AGAINST” or “ABSTAIN.” Abstentions will have no effect, and will not count as either a vote “FOR” or “AGAINST” the approval of the Adjournment Proposal.

Q. What do I do if I receive more than one proxy or set of voting instructions?

A. If you received more than one proxy card, your shares of Company common stock are likely registered in different names or with different addresses or are in more than one account. You must separately vote the shares of Company common stock shown on each proxy card that you receive in order for all of your shares of Company common stock to be voted at the meeting.

Q. What is householding and how does it affect me?

A. The SEC permits us to send a single set of proxy materials to any household at which two or more stockholders reside, unless contrary instructions have been received, but only if we provide advance notice and follow certain procedures. In such cases, each stockholder continues to receive a separate notice of the meeting and proxy card. Some banks, brokers, and other nominee record holders may be participating in the practice of “householding” proxy statements. If your family has multiple accounts holding Company common stock, you may have already received householding notification from your bank, broker or other nominee record holder. Please contact your bank, broker or other nominee record holder directly if you have any questions or require additional copies of this proxy statement. They will arrange for delivery of a separate copy of this proxy statement promptly upon your written or oral request. Alternatively, you may also contact the Company by written or oral request to Vigil Neuroscience, Inc., at 100 Forge Road, Suite 700, Watertown, Massachusetts 02472, Attention: Corporate Secretary, telephone: 857-254-4445. You may decide at any time to revoke your decision to household, and thereby receive multiple copies.

25

Q. What happens if I sell my shares of Company common stock before the Special Meeting?

A. The record date for stockholders entitled to vote at the Special Meeting is earlier than both the date of the Special Meeting and the consummation of the Merger. If you transfer your shares of Company common stock after the record date but before the Special Meeting, unless special arrangements (such as provision of a proxy) are made between you and the person to whom you transfer your shares of Company common stock and each of you notifies the Company in writing of such special arrangements, you will retain your right to vote such shares of Company common stock at the Special Meeting but will transfer the right to receive the Merger Consideration to the person to whom you transfer your shares of Company common stock. Even if you sell or otherwise transfer your Company common stock after the record date, we encourage you to complete, date, sign and return the accompanying proxy card or submit a proxy via the Internet or telephone.

Q. What happens if I sell my Company common stock after the Special Meeting but before the Effective Time?

A. If you transfer your shares of Company common stock after the Special Meeting but before the Effective Time, you will have transferred the right to receive the Merger Consideration to the person to whom you transfer your shares of Company common stock. In order to receive the Merger Consideration, you must hold your shares of Company common stock through the completion of the Merger.

Q. Who is paying for this proxy solicitation?

A. The Company has engaged Okapi Partners LLC (“Okapi”) to assist in the distribution and tabulation of proxies for the Special Meeting. The Company estimates that it will pay Okapi a fee of approximately $25,000 and postage expenses. The Company has agreed to reimburse Okapi for certain fees and expenses and will also indemnify Okapi, its affiliates and their respective officers, directors, employees and agents against certain losses, claims, damages, costs, charges, counsel fees and expenses, payments, expenses and liabilities. The Company may also reimburse banks, brokers or their agents for their expenses in forwarding proxy materials to beneficial owners of shares of Company common stock. Our directors, officers and employees may also solicit proxies by telephone, by facsimile, by mail, on the Internet or in person, but they will not be paid any additional amounts for soliciting proxies.

Q. What do I need to do now?

A. Even if you plan to attend the Special Meeting, after carefully reading and considering the information contained in this proxy statement, please promptly submit your proxy to ensure that your shares of Company common stock are represented at the Special Meeting. If you hold your shares of Company common stock in your own name as the stockholder of record, you may submit a proxy to have your shares of Company common stock voted at the Special Meeting in one of several ways: (i) using the Internet in accordance with the instructions set forth on the accompanying proxy card, (ii) calling toll-free at 1-800-690-6903 or (iii) completing, signing, dating and returning the accompanying proxy card in the accompanying prepaid reply envelope. If you decide to attend the Special Meeting and vote via the virtual meeting website, your vote via the virtual meeting website will revoke any proxy previously submitted. If you are a beneficial owner of Company common stock, please refer to the instructions provided by your bank, brokerage firm or other nominee to see which of the above choices are available to you.

Q. Should I surrender my shares now?

A. No. Any holder of Book-Entry Shares (as defined below) will not be required to deliver a certificate or an executed letter of transmittal to the Paying Agent to receive the Merger Consideration. For additional information, see the section titled “The Merger Agreement—Surrender and Payment Procedures” beginning on page 83 of this proxy statement.

26

Q. Am I entitled to exercise dissenters’ rights or rights of appraisal instead of receiving the Merger Consideration for my shares of Company common stock?

A. Yes. In order to exercise your appraisal rights, you must follow the requirements set forth in Section 262. Under Delaware law, if the Merger is consummated and certain conditions are met, Company stockholders or beneficial owners who continuously hold their shares of Company common stock through the Effective Time, do not vote in favor of the Transaction Proposal, properly demand in writing an appraisal of their shares delivered to the Company prior to the taking of the vote on the Transaction Proposal and otherwise comply with, and do not validly withdraw or otherwise lose their appraisal rights under, the applicable provisions of Delaware law will be entitled to appraisal rights to receive, in cash, the “fair value” of their shares of Company common stock as determined by the Delaware Court of Chancery in accordance with Section 262, the provisions of which are summarized in this proxy statement. If the Merger is consummated and certain conditions are met, Company stockholders and beneficial owners who properly exercise their appraisal rights in compliance with Section 262 will be entitled to have the Delaware Court of Chancery determine, and to be paid, the “fair value” of their shares of Company common stock, exclusive of any element or value arising from the accomplishment or expectation of the Merger, together with interest, if any, to be paid upon the amount determined to be the “fair value.” The appraisal amount could be more than, the same as or less than the amount a Company stockholder would be entitled to receive under the terms of the Merger Agreement. For additional information, see the section titled “Appraisal Rights.” The relevant section of the DGCL regarding appraisal rights, as in effect both at the time of the parties’ entry into the Merger Agreement, may be accessed without subscription or cost at the following publicly available website: https://delcode.delaware.gov/title8/c001/sc09/index.html#262. For additional information, see the section titled “The Special Meeting—Dissenters’ Rights” beginning on page 35 of this proxy statement.

Q. Who can help answer any other questions I might have?

A. If your shares are registered directly in your name through our transfer agent, or you have stock certificates registered in your name, and you need additional copies of this proxy statement or the accompanying proxy card or voting instructions, please contact our proxy tabulator by email or by phone:

Email: [email protected]

Stockholders Call (toll-free): (877) 869-0171

Banks and Brokers Call: (212) 297-0720

If your shares are held in the name of a bank, broker, or other nominee, you will receive instructions from your bank, broker, or other nominee of record if you need additional copies of this proxy statement or the accompanying proxy card or voting instructions.

27

CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS

Statements contained in this proxy statement and the documents to which we refer you in this proxy statement, as well as information included in oral statements or other written statements made or to be made by us, contain express or implied forward-looking statements, which are intended to be covered by the safe harbor provisions of the Private Securities Litigation Reform Act of 1995, as amended, and other applicable law. Such express or implied forward-looking statements, include, without limitation, statements regarding: the Company’s strategy, business plans and focus; the potential therapeutic benefit of the Company’s product candidates, including iluzanebart (“VGL101”) and VG-3927; the return of the rights to VGL101 to Amgen, Inc. (“Amgen”), the original licensor, under the Amgen Consent (as defined below) (the “VGL101 Return”); the progress and timing of the clinical development of the Company’s product candidates and programs; beliefs about observations made analyzing preclinical study and clinical trial data to date; and the future operations and performance of Parent and the Company. All statements other than statements of historical fact contained in this proxy statement are forward-looking statements, including all statements regarding the intent, belief or current expectation of the companies and members of their senior management teams. Words such as “will,” “could,” “would,” “should,” “may,” “expect,” “plan,” “design,” “anticipate,” “intend,” “believe,” “contemplate,” “estimate,” “predict,” “project,” “potential,” “possible,” “continue,” “target,” “seek,” variations of such words, or the negative of these words, and similar expressions may identify such forward-looking statements, although not all forward-looking statements contain these identifying words. Examples of such forward-looking statements include, but are not limited to, express or implied:

These statements are based on current beliefs, judgments and assumptions based upon information currently available the Company’s management and utilized to develop plans, estimates and projections. By their very nature, forward-looking statements involve inherent risks and uncertainties, both general and specific. The Company cautions that a number of important factors, including those described in this document, could cause actual results to differ materially from those contemplated in any forward-looking statements.

Factors that may affect future results and may cause these forward-looking statements to be inaccurate include, but are not limited to: the occurrence of any event, change or other circumstance that could give rise to the termination of the transaction; the possibility that competing offers will be made; the possibility that various closing conditions for the transaction may not be satisfied or waived, including that a governmental entity may prohibit, delay or refuse to grant approval for the consummation of the transaction (or only grant approval subject to adverse conditions or limitations) or the receipt of the requisite approval of the Company’s stockholders; the possibility that the proposed transaction may not be completed in the time frame expected, or at all; the possibility that the VGL101 Return may not be completed in the anticipated time frame or at all; failure to realize the anticipated benefits of the proposed transaction in the time frame expected, or at all; the effects of the transaction on relationships with employees, other business partners or governmental entities; potential adverse reactions or changes to business relationships resulting from the announcement or completion of the proposed

28

transaction; significant or unexpected costs, charges or expenses resulting from the proposed transaction; negative effects of this announcement on the market price of the Company’s common stock and/or Parent’s or the Company’s operating results; potential difficulties in employee retention as a result of the announcement and pendency of the proposed transaction; the difficulty of predicting the timing or outcome of regulatory approvals or actions; the risks related to non-achievement of the CVR milestone and that holders of the CVRs will not receive payments in respect of the CVRs; other business effects, including the effects of industry, economic or political conditions outside of the Company’s control; potentially significant political, trade or regulatory developments and other circumstances beyond the Company’s control, including government shutdowns, layoffs, voluntary resignations and reorganizations, new legislation and executive orders, trade disputes and tariffs; transaction costs; actual or contingent liabilities; risk of litigation and/or regulatory actions related to the proposed transaction; the outcome of any legal proceedings that may be instituted against the parties and others related to the proposed transaction; adverse impacts on business, operating results or financial condition in the future due to pandemics, epidemics or outbreaks and their impact on Parent’s and the Company’s respective businesses, operations, supply chain, patient enrollment and retention, clinical trials, strategy, goals and anticipated milestone; government-mandated or market-driven price decreases for Parent’s or the Company’s products; introduction of competing products; reliance on information technology; Parent’s or the Company’s ability to successfully market current and new products; Parent’s, the Company’s and their collaborators’ ability to continue to conduct research and clinical programs; the Company’s ability to successfully demonstrate the efficacy and safety of its product candidates, the therapeutic potential of its product candidates and the preclinical or clinical results for its product candidates, which may not support further development of such product candidates; comments, feedback and actions of regulatory agencies; exposure to product liability and legal proceedings and investigations; and other risks and uncertainties detailed from time to time in the Company’s periodic reports filed with the SEC and the Company’s other filings with the SEC.

Any forward-looking statements speak only as of the date of this proxy statement and are made based on the current beliefs, judgments and assumptions based upon information currently available to the Company’s management. Forward-looking statements contained in this proxy statement are made as of the date of this proxy statement, and the Company undertakes no duty to update publicly or revise such information except as required under applicable law. Readers should not rely upon the information on this page as current or accurate after its publication date. The Company operates in a very competitive and rapidly changing environment, and new risks emerge from time to time. It is not possible for Company’s management to predict all risks, nor assess the impact of all factors on the Company’s business or the extent to which any factor, or combination of factors, may cause actual results to differ materially from those contained in any forward-looking statements the Company may make. You should read this proxy statement and the documents that the Company files with the SEC with the understanding that the Company’s actual future results, levels of activity, performance, and events and circumstances may be materially different from what the Company expects.

29

PARTIES TO THE MERGER

Vigil Neuroscience, Inc.

The Company, a Delaware corporation, is a clinical-stage biotechnology company dedicated to improving the lives of patients, caregivers and families affected by rare and common neurodegenerative diseases by pursuing the development of disease-modifying therapeutics to restore the vigilance of microglia. Microglia are the sentinel immune cells of the brain and play a critical role in maintaining central nervous system health and responding to damage caused by disease. Leveraging recent research implicating microglial dysfunction in neurodegenerative diseases, the Company utilizes a precision medicine approach to develop a pipeline of therapeutic candidates, initially addressing genetically defined patient subpopulations, that it believes will activate and restore microglial function. The Company’s first therapeutic candidates are designed to activate Triggering Receptor Expressed on Myeloid Cells 2 (“TREM2”), a key microglial receptor protein that mediates responses to environmental signals in order to maintain brain health and whose dysfunction is linked to neurodegeneration. The Company has two clinical programs that are designed to target TREM2. The Company’s first clinical candidate, iluzanebart (“VGL101”), is a fully human monoclonal antibody TREM2 agonist that recently completed a Phase 2 clinical trial in patients with adult-onset leukoencephalopathy with axonal spheroids and pigmented glia, a rare and fatal neurodegenerative disease. The Company’s second clinical candidate, VG-3927, is an orally bioavailable small molecule TREM2 agonist that is being developed for the potential treatment of Alzheimer’s disease.

The Company’s principal executive office is located at 100 Forge Road, Suite 700, Watertown, MA 02472. The Company’s telephone number is (857) 254-4445. The Company website address is www.vigilneuro.com/. The Company common stock is listed and trades on Nasdaq under the symbol “VIGL.”

The information provided on the Company’s website is not part of this proxy statement and is not incorporated in this proxy statement by reference here or by any other reference to its website provided in this proxy statement. Additional information about the Company is contained in certain of its public filings that are incorporated by reference into this proxy statement. See “Where You Can Find More Information.”

Sanofi

Parent is a société anonyme, a form of limited liability company, organized under the laws of France. Parent is a leading global healthcare company, focused on patient needs and engaged in the research, development, manufacture and marketing of therapeutic solutions. Parent’s principal executive office is located at 46, avenue de la Grande Armée, 75017 Paris, France.

Vesper Acquisition Sub, Inc.

Merger Sub was incorporated in Delaware on April 16, 2025, as a wholly owned subsidiary of Parent, solely for the purpose of engaging in the Transactions (as defined below), including the Merger.

Merger Sub has not carried on any activities on or prior to the date of this proxy statement, except for activities incidental to its formation and activities undertaken in connection with the Transactions, including the structuring and negotiation of the Transactions. Upon completion of the Merger, Merger Sub will be merged with and into the Company, and Merger Sub will cease to exist.

30

THE SPECIAL MEETING

This proxy statement is being provided to the stockholders of the Company as part of a solicitation of proxies by the Board of Directors for use at the special meeting to be held at the time specified below, and at any properly convened meeting following an adjournment or postponement thereof. This proxy statement provides stockholders of the Company with the information they need to know to be able to vote or instruct their vote to be cast at the Special Meeting or any adjournment or postponement thereof.

Date, Time and Place of the Special Meeting

This proxy statement is being furnished to our stockholders as part of the solicitation of proxies by the Board of Directors for use at the Special Meeting to be held online on August 4, 2025, at 8:30 a.m., Eastern Time, or at any postponement or adjournment thereof. You will be able to attend the Special Meeting by registering at www.virtualshareholdermeeting.com/VIGL2025SM and entering your 16-digit control number included in your proxy materials.

Purpose of the Special Meeting

At the Special Meeting, holders of record as of the close of business on June 26, 2025 of Company common stock will be asked to consider and vote on:

We do not expect that any matters other than the proposals set forth above will be brought before the Special Meeting, and only matters specified in the notice of the meeting may be acted upon at the Special Meeting.

The Board of Directors unanimously recommends that you vote “FOR” each of the above proposals.

Our stockholders must approve the Transaction Proposal in order for the Merger to occur. If our stockholders fail to approve the Transaction Proposal, the Merger will not occur. A copy of the Merger Agreement is attached as Annex A to this proxy statement. We encourage you to read the Merger Agreement carefully and in its entirety.

Record Date and Quorum

The Board of Directors has fixed the close of business on June 26, 2025, as the record date for the Special Meeting, and only holders of record of shares of Company common stock on the record date are entitled to notice of, and to vote at (in person by proxy), the Special Meeting.

You are entitled to receive notice of, and to vote at, the Special Meeting and at any adjournment or postponements thereof if you owned Company common stock at the close of business on the record date. You will be entitled to one vote for each share of Company common stock that you owned at the close of business on the record date. As of the close of business on the record date, there were 47,686,561 shares of Company common stock outstanding and entitled to vote at the Special Meeting, held by seven stockholders of record. You will be entitled to one vote on all matters properly coming before the Special Meeting for each share of Company common stock that you owned on the record date.

Holders of a majority of the outstanding shares of Company common stock entitled to vote constitute a quorum for the purposes of the Special Meeting. Shares of Company common stock represented at the Special Meeting but not voted, including shares of Company common stock for which proxies have been received but for which stockholders have abstained, will be treated as present at the Special Meeting for purposes of determining

31

the presence or absence of a quorum for the transaction of all business. In the event that a quorum is not present at the Special Meeting, the Special Meeting may be adjourned or postponed to solicit additional proxies. Pursuant to the bylaws, approval of the adjournment of the Special Meeting in a situation in which a quorum is not present or represented at the Special Meeting requires the affirmative vote of holders of a majority of the shares of Company common stock present at the Special Meeting and entitled to vote on the proposal. Approval of the Adjournment Proposal requires the affirmative vote of the holders of a majority of the shares of Company common stock present at the Special Meeting and entitled to vote on the proposal.

Attendance

Only stockholders of record as of the record date, their duly authorized proxy holders, beneficial stockholders with proof of ownership and our guests may attend the Special Meeting.

Vote Required

Approval of the Transaction Proposal requires the affirmative vote of holders of a majority of the issued and outstanding shares of Company common stock entitled to vote on the Transaction Proposal. For the Transaction Proposal, you may vote “FOR,” “AGAINST” or “ABSTAIN.” Abstentions will have the same effect as a vote “AGAINST” the Transaction Proposal. If your shares of Company common stock are registered directly in your name with our transfer agent, you are considered, with respect to those shares of Company common stock, the “stockholder of record.” This proxy statement and proxy card have been sent directly to you by the Company.

The approval of the Adjournment Proposal requires the affirmative vote of holders of a majority of shares of Company common stock properly cast for and against the Adjournment Proposal at the Special Meeting and entitled to vote on the Adjournment Proposal. For the Adjournment Proposal, you may vote “FOR,” “AGAINST” or “ABSTAIN.” For purposes of the Adjournment Proposal, if you attend the Special Meeting and abstain on such proposal, or if you have submitted a proxy and abstained on such proposal, this will have no effect on the outcome of the Adjournment Proposal, and it will not be counted as either “FOR” or “AGAINST” the Adjournment Proposal.

If your shares of Company common stock are registered directly in your name with our transfer agent, you are considered, with respect to those shares of Company common stock, the “stockholder of record.” This proxy statement and proxy card have been sent directly to you by the Company.

If your shares of Company common stock are held through a bank, brokerage firm or other nominee, you are considered the “beneficial owner” of shares of Company common stock held in street name. In that case, this proxy statement has been forwarded to you by your bank, brokerage firm or other nominee who is considered, with respect to those shares of Company common stock, the stockholder of record. As the beneficial owner, you have the right to direct your bank, brokerage firm or other nominee how to vote your shares of Company common stock by following their instructions for voting.

Banks, brokerage firms or other nominees who hold shares in street name for customers generally have the authority to vote on “routine” proposals when they have not received instructions from beneficial owners. However, banks, brokerage firms and other nominees are precluded from exercising their voting discretion with respect to approving non-routine matters, including the Transaction Proposal and Adjournment Proposal, and, as a result, absent specific instructions from the beneficial owner of such shares of Company common stock, banks, brokerage firms or other nominees are not empowered to vote those shares of Company common stock on non-routine matters. Any broker non-votes would be counted for purposes of determining a quorum at the Special Meeting and as votes “AGAINST” the Transaction Proposal. Because none of the proposals to be voted on at the Special Meeting are routine matters for which brokers may have discretionary authority to vote, the Company does not expect any broker non-votes at the Special Meeting.

32

If you are a stockholder of record, you may have your shares of Company common stock voted on matters presented at the Special Meeting in any of the following ways:

If you are a beneficial owner, you should receive instructions from your bank, brokerage firm or other nominee that you must follow in order to have your shares of Company common stock voted. Those instructions will identify which of the above choices are available to you in order to have your shares of Company common stock voted. Please note that if you are a beneficial owner and wish to vote via the virtual meeting website at the Special Meeting, you must provide a legal proxy from your bank, brokerage firm or other nominee at the Special Meeting.

Please refer to the instructions on your proxy or voting instruction card to determine the deadlines for submitting your proxy over the Internet or by telephone. If you choose to submit a proxy by mailing a proxy card, your proxy card should be mailed in the accompanying prepaid reply envelope, and your proxy card must be filed with our corporate secretary by the time the Special Meeting begins.

If you submit a proxy, regardless of the method you choose to submit such proxy, the individuals named on the accompanying proxy card, and each of them, with full power of substitution, will vote your shares of Company common stock in the way that you indicate. When completing the Internet or telephone processes or the proxy card, you may specify whether your shares of Company common stock should be voted for or against or to abstain from voting on all, some or none of the specific items of business to come before the Special Meeting.

If you properly sign your proxy card but do not mark the boxes showing how your shares of Company common stock should be voted on a matter, the shares of Company common stock represented by your properly signed proxy will be voted “FOR” approval of the Transaction Proposal and “FOR” approval of the Adjournment Proposal.

IT IS IMPORTANT THAT YOU VOTE YOUR SHARES OF COMPANY COMMON STOCK AT THE SPECIAL MEETING PROMPTLY. WHETHER OR NOT YOU PLAN TO ATTEND THE SPECIAL MEETING, PLEASE COMPLETE, DATE, SIGN AND RETURN, AS PROMPTLY AS POSSIBLE, THE ACCOMPANYING PROXY CARD IN THE ACCOMPANYING PREPAID REPLY ENVELOPE, OR SUBMIT YOUR PROXY BY TELEPHONE OR THE INTERNET. STOCKHOLDERS WHO ATTEND THE SPECIAL MEETING MAY REVOKE THEIR PROXIES BY VOTING VIA THE VIRTUAL MEETING WEBSITE.

As of the close of business on the record date, the Supporting Stockholders collectively beneficially owned approximately 16.54% of the total voting power of the outstanding shares of Company common stock.

33

Proxies and Revocation

Any stockholder of record entitled to vote at the Special Meeting may submit a proxy by telephone, over the Internet or by returning the accompanying proxy card in the envelope provided, or may vote via the virtual meeting website by attending the Special Meeting. If your shares of Company common stock are held in “street name” through a bank, brokerage firm or other nominee, you should instruct your bank, brokerage firm or other nominee on how to vote your shares of Company common stock using the instructions provided by your bank, brokerage firm or other nominee. If you fail to submit a proxy or to vote via the virtual meeting website at the Special Meeting, or do not provide your bank, brokerage firm or other nominee with instructions, as applicable, your shares of Company common stock will be treated as a vote “AGAINST” the proposal to approve the Transaction Proposal and have no effect on the proposal to adopt the Adjournment Proposal.

You have the right to revoke a proxy, whether submitted over the Internet, by telephone or by mail, at any time before it is exercised, by submitting a proxy at a later date through any of the methods available to you, by giving written notice of revocation to the Company’s corporate secretary, which must be filed with the corporate secretary by 5:00 p.m. Eastern Time on the business day immediately prior to the date of the Special Meeting, or by virtually attending the Special Meeting and by voting via the virtual meeting website. Virtually attending the Special Meeting alone, without voting at the Special Meeting, will not be sufficient to revoke your proxy. Written notice of revocation should be mailed to: Vigil Neuroscience, Inc., 100 Forge Road, Suite 700, Watertown, MA 02472, Attention: Corporate Secretary.

Adjournments

Although not currently expected, the Special Meeting may be adjourned, if necessary, desirable or appropriate, to solicit additional proxies if, at the time of the Special Meeting, there are an insufficient number of votes in favor of adopting the Transaction Proposal. Pursuant to the bylaws, approval of the adjournment of the Special Meeting in a situation in which a quorum is not present or represented by proxy at the Special Meeting requires either (i) the affirmative vote of the holders of Company common stock representing a majority of the voting power present at the Special Meeting and entitled to vote on the Adjournment Proposal, or (ii) the presiding officer of the Special Meeting to adjourn the meeting. The Special Meeting may be held as adjourned without further notice other than an announcement at the Special Meeting at which the adjournment or postponement is taken of the hour, date and place, if any, to which the Special Meeting is adjourned and the means of remote communications, if any, by which the holders of Company common stock and proxy holders may be deemed to be present and vote at such adjourned Special Meeting. However, the bylaws provide that if any such adjournment is for more than 30 days, or if after an adjournment a new record date for determining stockholders entitled to vote is fixed for the adjourned Special Meeting, a notice of the adjourned meeting and the means of remote communications, if any, by which stockholders and proxyholders may be deemed to be present in person and vote at such adjourned Special Meeting, shall be given to each stockholder of record entitled to vote at the adjourned Special Meeting. Any adjournment of the Special Meeting for the purpose of soliciting additional proxies will allow the Company’s stockholders who have already sent in their proxies to revoke them at any time prior to their use at the Special Meeting as adjourned.

Anticipated Date of Completion of the Merger

We are working towards completing the Merger as soon as possible. Assuming timely receipt of required regulatory approvals and satisfaction of other closing conditions, including approval by our stockholders of the Transaction Proposal, we anticipate that the Merger will be completed in the third quarter of 2025. If our stockholders vote to approve the Transaction Proposal, the Merger will become effective as soon as practicable following the satisfaction or waiver of the other conditions to the Merger, subject to the terms of the Merger Agreement. For additional information, see the section titled “The Merger Agreement—Closing and Effective Time of the Merger” beginning on page 80 on this proxy statement.

34

Dissenters’ Rights

If the Merger is consummated and certain conditions are met, the Company’s stockholders or beneficial owners who continuously hold their shares of Company common stock through the Effective Time, who do not vote in favor of nor consent to the Transaction Proposal, who properly demand in writing an appraisal of their shares delivered to the Company prior to the taking of the vote on the Transaction Proposal and who comply with, and do not validly withdraw their demands or otherwise lose their appraisal rights under, the applicable provisions of Delaware law will be entitled to appraisal rights to receive, in cash, the fair value of their shares as determined by the Delaware Court of Chancery under Section 262. This means that the Company’s stockholders or beneficial owners may be entitled to have their shares of Company common stock appraised by the Delaware Court of Chancery, and to receive payment in cash of the “fair value” of their shares of Company common stock, exclusive of any elements of value arising from the accomplishment or expectation of the Merger, together with interest, if any, to be paid on the amount determined to be “fair value” (or in certain circumstances described in further detail in the section of this proxy statement titled “Appraisal Rights,” on the difference between the amount determined to be the “fair value” and the amount paid by the Surviving Corporation in the Merger to each Company stockholder entitled to appraisal prior to the entry of judgment in any appraisal proceeding). Due to the complexity of the appraisal process, the Company’s stockholders or beneficial owners who wish to seek appraisal of their shares of Company common stock are encouraged to seek the advice of legal counsel with respect to the exercise of appraisal rights.

The Company’s stockholders or beneficial owners considering seeking appraisal should be aware that the “fair value” of their shares as determined pursuant to Section 262 could be more than, the same as, or less than the value of the Merger Consideration that they would receive pursuant to the Merger Agreement if they did not seek appraisal of their shares of Company common stock.

To exercise appraisal rights, the Company’s stockholders must: (i) deliver a written demand for appraisal to the Company before the vote is taken on the Transaction Proposal at the Special Meeting; (ii) not submit a proxy or otherwise vote in favor of the Transaction Proposal; (iii) continue to hold shares of Company common stock of record through the Effective Time; and (iv) comply with all other procedures for exercising and perfecting appraisal rights under the DGCL. Failure to follow the procedures specified under the DGCL will result in the loss of appraisal rights. In addition, the Delaware Court of Chancery will dismiss appraisal proceedings as to all persons who otherwise would be entitled to appraisal rights unless certain stock ownership conditions are satisfied by the Company’s stockholders who properly and timely demand appraisal in accordance with Section 262. The DGCL requirements for exercising and perfecting appraisal rights are described in further detail in this proxy statement, which is qualified in its entirety by Section 262. The relevant section of the DGCL regarding appraisal rights, as in effect at the time of the parties’ entry into the Merger Agreement, may be accessed without subscription or cost at the following publicly available website: https://delcode.delaware.gov/title8/c001/sc09/index.html#262.

If you hold your shares of Company common stock through a bank, broker or other nominee and you wish to exercise appraisal rights, you may make a written demand for appraisal in your own name, but you must satisfy the conditions set forth above and your written demand must also reasonably identify the holder of record of the shares for which demand is made, be accompanied by documentary evidence of your beneficial ownership of stock (such as a brokerage or securities account statement containing such information or a letter from a broker or other record holder of such shares confirming such information) and a statement that such documentary evidence is a true and correct copy of what it purports to be, and provide an address at which you consent to receive notices given by the Surviving Corporation under Section 262 and to be set forth on the verified listed required by Section 262(f) of the DGCL. For additional information, see the section titled “Appraisal Rights” beginning on page 109 of this proxy statement.

35

Solicitation of Proxies; Payment of Solicitation Expenses

The Company has engaged Okapi to assist in the solicitation of proxies for the Special Meeting. The Company estimates that it will pay Okapi a fee of approximately $25,000 and postage expenses. The Company has agreed to reimburse Okapi for certain fees and expenses and will also indemnify Okapi, its affiliates and their respective officers, directors, employees and agents against certain losses, claims, damages, costs, charges, counsel fees and expenses, payments, expenses and liabilities. The Company may also reimburse banks, brokers or their agents for their expenses in forwarding proxy materials to beneficial owners of shares of Company common stock. Our directors, officers and employees may also solicit proxies by telephone, by facsimile, by mail, on the Internet or in person, but they will not be paid any additional amounts for soliciting proxies.

Questions and Additional Information

If your shares are registered directly in your name through our transfer agent, or you have stock certificates registered in your name, and you need additional copies of this proxy statement or the accompanying proxy card or voting instructions, please contact our proxy tabulator by email or by phone:

Email: [email protected]

Stockholders Call (toll-free): (877) 869-0171

Banks and Brokers Call: (212) 297-0720

If your shares are held in the name of a bank, broker, or other nominee, you will receive instructions from your bank, broker, or other nominee of record if you need additional copies of this proxy statement or the accompanying proxy card or voting instructions.

36

THE VOTING AND SUPPORT AGREEMENTS

In connection with the execution of the Merger Agreement, Ivana Magovčević-Liebisch, the Company’s chief executive officer, Bruce Booth, Atlas Venture Fund XII, L.P. and Atlas Venture Opportunity Fund I, L.P. (the “Supporting Stockholders”) entered into voting and support agreements (the “Voting and Support Agreements”) with Parent. Each of the Voting and Support Agreements follows the same form. The following is a summary of the material provisions of the Voting Support Agreements, a copy of which is attached as Annex B to this proxy statement and is incorporated into this proxy statement by reference.

As of the close of business on the record date, the Supporting Stockholders collectively beneficially owned approximately 16.54% of the total voting power of the outstanding shares of Company common stock. In the event any Supporting Stockholder acquires record ownership or beneficial ownership of shares of Company common stock after the execution of the Voting and Support Agreement, such additional shares will automatically become subject to the Voting and Support Agreement. The shares of Company common stock subject to the Voting and Support Agreement are referred to in this section as “Covered Shares.”

Voting Provisions

Under the Voting and Support Agreements, each Supporting Stockholder agreed to vote or cause to be voted all Covered Shares: (i) in favor of (a) the adoption of the Merger Agreement, the Merger and the approval of all agreements related to the Merger and any actions related thereto; (b) without limitation of the preceding clause (a), the approval of any proposal to adjourn or postpone any such meeting to a later date if there are not sufficient votes for adoption of the Merger Agreement on the date on which such meeting is held and (c) each of the transactions contemplated by the Merger Agreement; (ii) against approval of any proposal made in opposition to, in competition with, or inconsistent with, the Merger Agreement, the Merger or any other transactions contemplated by the Merger Agreement; (iii) against any of the following actions (other than those actions that relate to the approval of the Merger or any other transactions contemplated by the Merger Agreement) (a) merger, consolidation, statutory conversion, statutory domestication, statutory transfer, share exchange, business combination, sale of assets, reorganization or recapitalization of or involving the Company or any of its subsidiaries, (b) sale, lease, exchange, transfer or other disposition of a material amount of the assets of the Company or any of its subsidiaries, (c) any reorganization, recapitalization, dissolution, liquidation or winding up of the Company or any of its subsidiaries, (d) any material change in the capitalization of the Company or any of its subsidiaries, or the corporate structure of the Company or any of its subsidiaries or any amendment, modification, supplement or other change in the Company’s organizational documents, (e) any Transaction Proposal or (f) any other action, proposal, transaction or agreement that would reasonably be expected to materially prevent, nullify, impede, interfere with, delay, postpone, frustrate, discourage or adversely affect the Merger or any other transactions contemplated by the Merger Agreement; (iv) against any action, proposal, transaction or agreement that would reasonably be expected to result in a breach in any respect of any covenant, representation or warranty or any other obligation or agreement of the Company contained in the Merger Agreement, or of the applicable Supporting Stockholder contained in the Voting and Support Agreement; and (v) in favor of any other matter necessary or appropriate to the consummation of the transactions contemplated by the Merger Agreement, including the Merger.

Each Supporting Stockholder also has agreed that at any meeting of the Company stockholders, however called, or at any adjournment or postponement thereof, or in any other circumstance in which the vote, consent or other approval of the Company stockholders is sought (including the Special Meeting), will appear (in person or by proxy) at each such meeting or otherwise cause all Covered Shares to be counted as present thereat for purposes of calculating a quorum.

Restrictions on Transfer

Pursuant to the Voting and Support Agreement, subject to certain limited exceptions, each Supporting Stockholder agreed that, during the term of the Voting and Support Agreement, it will not directly or indirectly

37

sell, assign, transfer, pledge, encumber, grant a security interest in, hypothecate, gift, distribute, or otherwise dispose of (whether by sale, merger, consolidation, statutory conversion, statutory domestication, statutory transfer, share exchange, business combination transaction, by operation of law or otherwise), or enter into any Contract, option, put, call or other agreement arrangement or understanding with respect to such transfer.

Waiver of Appraisal Rights

Under the Voting and Support Agreement, the Supporting Stockholders irrevocably waived and agree not to exercise any and all rights of appraisal, dissenters’ rights or any similar rights, including pursuant to Section 262, in respect of such Covered Shares that the Supporting Stockholder may have or that may arise in connection with the Merger.

Termination

The Voting and Support Agreements will terminate automatically, without any notice or other action by any person, upon the earliest of (i) such date and time as the Merger Agreement shall have been validly terminated, (ii) the Effective Time, (iii) with respect to each Supporting Stockholder, the delivery of written notice of termination by such Supporting Stockholder to Parent following an adverse amendment to the Merger Agreement made without the consent of such Supporting Stockholder, or (iv) with respect to each Supporting Stockholder, mutual written agreement of such Supporting Stockholder and Parent to terminate the Voting and Support Agreement.

Stockholder Capacity Only

Each of the Supporting Stockholders has entered into a Voting and Support Agreement solely in such Supporting Stockholder’s capacity as a stockholder of the Company, and not in such Supporting Stockholder’s capacity as a director, officer or employee of the Company, as applicable. Nothing in the Voting and Support Agreement will be construed to prohibit the Supporting Stockholder from taking any action (or omitting to take any action) in his or her capacity as an officer or member of the Board of Directors or from taking any action with respect to any Transaction Proposal solely in his or her capacity as such an officer or director or in the exercise of his or her fiduciary duties in his or her capacity as director or officer of the Company, or prevent or be construed to create any obligation on the part of any director or officer of the Company from taking any action in his or her capacity as such director or officer.

38

THE TRANSACTION (PROPOSAL NO. 1)

The Company is requesting stockholders to adopt and approve the Merger Agreement. For a summary of and detailed information regarding this proposal, see the information about the Merger Agreement and the Merger throughout this proxy statement, including the information set forth in the sections of this proxy statement entitled “The Merger” and “The Merger Agreement.” This summary does not purport to be complete and may not contain all of the information about the Merger that is important to you. A copy of the Merger Agreement is attached to this proxy statement as Annex A. You are urged to read the Merger Agreement carefully in its entirety.

THE BOARD OF DIRECTORS UNANIMOUSLY RECOMMENDS THAT STOCKHOLDERS VOTE “FOR” THE TRANSACTION PROPOSAL.

39

THE MERGER

Background of the Merger

The following chronology summarizes the key meetings and events that led to the signing of the Merger Agreement. The following chronology does not purport to catalogue every conversation among the Board of Directors, the Transaction Committee (as defined below) or the representatives of Vigil, Sanofi and other parties.

Vigil is a clinical-stage biotechnology company dedicated to improving the lives of patients, caregivers, and families affected by rare and common neurodegenerative diseases by pursuing the development of disease-modifying therapeutics to restore the vigilance of microglia, which are the sentinel immune cells of the brain and play a critical role in maintaining central nervous system health and responding to damage caused by disease. Leveraging recent research implicating microglial dysfunction in neurodegenerative diseases, Vigil is utilizing a precision medicine approach to develop a pipeline of therapeutic candidates, initially addressing genetically defined patient subpopulations, that the Company believes will activate and restore microglial function. Vigil’s therapeutic candidates are designed to activate TREM2, a key microglial receptor protein that mediates responses to environmental signals in order to maintain brain health and whose dysfunction is linked to neurodegeneration. Vigil has two clinical programs that are designed to target TREM2: (i) VGL101, a fully human monoclonal antibody TREM2 agonist, which is being returned to Amgen, the original licensor, pursuant to the terms of the Amgen Consent; and (ii) VG-3927, an orally bioavailable small molecule TREM2 agonist that is being developed for the potential treatment of Alzheimer’s disease.

The Company’s senior management and the Board of Directors regularly review the Company’s performance and prospects in light of its business and developments in the biopharmaceutical industry and potential strategic opportunities to enhance stockholder value. As part of this process, from time to time, the Company’s senior management has engaged in business development and/or strategic partnering discussions with participants in the biopharmaceutical industry, including Sanofi, and has reported regularly to the Board of Directors on potential partnering and collaboration opportunities.

In addition, from time to time, the Company has received unsolicited inquiries or non-binding offers from various parties who have expressed a desire to discuss whether there would be mutual interest in a potential strategic transaction involving the Company, including strategic parties who have engaged or sought to engage in discussions with other companies within Vigil’s industry.

For example, following meetings at the 2024 J.P. Morgan Annual Healthcare Conference in San Francisco, California, in February 2024, a global, publicly-traded pharmaceutical company (“Party A”) sent the Company a written non-binding proposal to acquire the Company for upfront cash and non-tradable CVRs payable in cash (the “February 2024 Party A Proposal”). The February 2024 Party A Proposal indicated that it was subject to Party A’s completion of due diligence, including a review of an unredacted copy of the Exclusive License Agreement, dated July 9, 2020 (including the related Letter Agreement, dated June 29, 2021) by and between the Company and Amgen (“Amgen License”) and related documents, and the negotiation of a definitive agreement.

Following receipt of the February 2024 Party A Proposal, from February 2024 through June 2024, as directed by the Board of Directors, the Company’s senior management and representatives of Centerview Partners LLC (“Centerview”), which, given its relationship and knowledge of Vigil was requested by Vigil’s senior management to provide initial guidance and support to the Company, contacted six large pharmaceutical companies (not including Sanofi), including two additional global, publicly-traded pharmaceutical companies (referred to as “Party B” and “Party C”), regarding interest in a potential acquisition of the Company. Each of Party A and Party B entered into a new confidentiality agreement or amended existing confidentiality agreements with the Company to facilitate further discussions. These confidentiality agreements included customary non-disclosure and non-use provisions, but no express standstill provisions. Party A and Party B were each given access to due diligence information regarding the Company, and Vigil senior management engaged in discussions with, and responded to due diligence requests from, such parties from time to time.

40

In March 2024, Party B sent the Company a written non-binding proposal to acquire the Company for upfront cash and CVRs payable in cash, the closing of which would be conditioned upon a concurrent spin-off of the VGL101 business to the Company’s stockholders (the “March 2024 Party B Proposal”). The March 2024 Party B Proposal indicated that it was subject to Party B’s completion of due diligence and satisfactory treatment of the intellectual property licensed from Amgen. None of the other five parties which were contacted by the Company’s senior management and representatives of Centerview, including Party C, expressed an interest in pursuing a potential acquisition of the Company and discussions did not progress beyond the preliminary phase.

Between March 2024 and June 2024, members of the Company’s senior management and representatives of Centerview, as directed by the Board of Directors, discussed a potential transaction with representatives of Party A and Party B and a potential increase to the value offered. Although Party B did increase its offer price modestly, neither Party A nor Party B were willing to increase their offer prices in any meaningful way before the Company’s anticipated release of incremental data and therefore, the Board of Directors determined to discontinue discussions with Party A and Party B with respect to a potential sale transaction at that time.

In March 2024, senior representatives of Sanofi contacted the Company to discuss a potential licensing transaction involving VG-3927. In connection with such discussions, on April 12, 2024, the Company and Sanofi entered into a confidentiality agreement, which did not include an express standstill provision. In March 2024 and April 2024, senior representatives of Sanofi had calls with Vigil management during which the Company indicated that the Company may be amenable to discussing a transaction involving an investment by Sanofi in the Company in return for the issuance of preferred stock in the Company and the granting of a limited exclusive right of first negotiation with respect to VG-3927.

On April 30, 2024, Sanofi sent Vigil a non-binding written proposal, which proposed a $40.0 million strategic investment by Sanofi in the Company for the purchase of non-voting preferred shares of the Company, as well as the receipt of an exclusive right of first negotiation for an exclusive worldwide license to develop and commercialize the Company’s TREM2 small molecule program, including VG-3927. Between April and June 2024, Sanofi conducted diligence on the Company and the Company and Sanofi negotiated the terms for such transaction.

On June 26, 2024, the Board of Directors held a meeting at which members of management and representatives from Goodwin Procter LLP (“Goodwin”), the Company’s outside counsel, were present. At this meeting, Ivana Magovčević-Liebisch, PhD, JD, Chief Executive Officer of the Company, summarized the key transaction terms of the securities purchase agreement with Aventis Inc., a subsidiary of Sanofi, pursuant to which Sanofi would make a $40.0 million strategic investment in the Company through the purchase of 537,634 of the Company’s Series A non-voting preferred shares (the “Series A Preferred Stock Transaction”). In connection with the Series A Preferred Stock Transaction, Vigil would grant Sanofi the exclusive right of first negotiation (the “ROFN Agreement”) for a license, grant or transfer of rights to research, develop, manufacture and commercialize the Company’s small molecule TREM2 agonist program, including its clinical candidate, VG-3927 (the “Exclusive VG-3927 License”), which would allow the Company to continue to develop VG-3927 independently and potentially increase the value of the asset while allowing the Company to pursue other strategic transactions, as the exclusive right did not include for example, transactions involving VGL101 or a transaction providing for the sale of the entire Company. Following discussion, the Board of Directors approved the Series A Preferred Stock Transaction, and on June 27, 2024, the Company entered into and publicly announced the Series A Preferred Stock Transaction.

During late 2024 and early 2025, Party A, Party B, Party C and Sanofi contacted Vigil to inquire as to whether Vigil would be interested in meeting with such parties at the 2025 J.P. Morgan Annual Healthcare Conference in San Francisco, California (the “2025 J.P. Morgan Conference”) to discuss recent updates to the Company’s business and have preliminary discussions regarding pursuing a potential strategic transaction with the Company, which, in the case of Party A, Party B, and Party C, would be a continuation of the conversations the parties had between March 2024 and June 2024 regarding a transaction providing for the sale of the

41

Company. Each of Party A, Party B and Party C entered into amendments to existing confidentiality agreements with Vigil to facilitate those discussions, which amended agreements included customary non-disclosure and non-use provisions, but no express standstill provisions. During the same period, Vigil contacted or was contacted by multiple biotech and pharmaceutical companies, including a privately-held pharmaceutical company (“Party D”), to inquire as to whether the parties would be interested in meeting with the Company at the 2025 J.P. Morgan Conference to discuss recent updates to the Company’s business and have preliminary discussions regarding pursuing a potential partnering relationship with respect to VGL101. Eight parties, including Party D, entered into a confidentiality agreement or an amendment to an existing confidentiality agreement with Vigil to facilitate further discussion. These confidentiality agreements included customary non-disclosure and non-use provisions, but no express standstill provisions.

From August 2024 to March 2025, pursuant to and in compliance with the ROFN Agreement, members of Vigil management engaged in discussions with Sanofi regarding the Exclusive VG-3927 License, and Sanofi conducted due diligence and reviewed certain Vigil materials in a virtual data room maintained for purposes of the ROFN Agreement.

In January 2025, while in attendance at the 2025 J.P. Morgan Conference, pursuant to and in compliance with the ROFN Agreement, representatives of Vigil, including Dr. Magovčević-Liebisch, met with representatives of each of Party A, Party B, and Party C regarding a potential strategic transaction providing for the sale of the Company, met with representatives of Sanofi regarding VG-3927, and met with representatives of 17 biotech and pharmaceutical companies, including Party D, and engaged in exploratory conversations with respect to the possibility of a potential partnering relationship with respect to VGL101.

On January 23, 2025, the Company issued a press release announcing positive data from its completed Phase 1 clinical trial evaluating VG-3927 in healthy adults and study subjects with Alzheimer’s disease.

Following the release of the positive data from the Company’s completed Phase 1 clinical trial evaluating VG-3927 on January 23, 2025, and the delivery of a data package regarding such clinical trial to Sanofi pursuant to the ROFN Agreement, beginning on February 25, 2025, representatives of Vigil and Sanofi exchanged drafts of a concept sheet for the key terms of the Exclusive VG-3927 License.

On March 17, 2025, Sanofi sent Vigil a notice of interest pursuant to the ROFN Agreement confirming that Sanofi desired to enter into exclusive negotiations with Vigil with respect to a transaction covered by the ROFN Agreement.

On March 18, 2025, Party A sent Vigil an unsolicited, written and non-binding proposal to acquire all of the outstanding shares of the Company for $8.00 per share in cash in upfront consideration and an additional $2.00 in cash per share in the form of CVRs, $1.00 of which would be payable upon submission to the U.S. Food and Drug Administration (“FDA”) of a Biologics License Application for VGL101 and $1.00 of which would be payable upon the first patient first dose of a Phase 3 study for VG-3927 (the “March 18 Party A Proposal”). The March 18 Party A Proposal specified that it was contingent upon Vigil and Amgen’s agreement to amend the Amgen License in a way that was suitable to Party A.

Also on March 18, 2025, the Board of Directors held a meeting at which members of Vigil management and representatives of Centerview and Goodwin were present. At this meeting, the meeting participants (without representatives of Centerview present) discussed the selection of financial advisors to assist the Board of Directors in a review of strategic alternatives based on, among other factors, the advisor’s qualifications, professional reputation and industry expertise. Based on those factors, along with its understanding of the Company and its business, the Board of Directors selected Centerview to assist with this review and directed Vigil management to negotiate the terms of Centerview’s engagement. Members of Vigil management and representatives of Centerview then reviewed the March 18 Party A Proposal with the Board of Directors. Goodwin provided an overview of the Board of Directors’ fiduciary duties in the context of evaluating a potential sale of the Company for cash and Centerview provided an overview of its preliminary financial analyses of Vigil.

42

Dr. Magovčević-Liebisch led a discussion regarding the current macro-economic conditions and financial trends, and the fundraising that would be needed to support the Company’s operations as a standalone entity in the near future. The Board of Directors had a discussion regarding whether any other pharmaceutical and biotechnology companies might have interest in a potential strategic transaction with Vigil, including weighing the potential benefits of outreach to other potential counterparties against the potential risks, such as the risk of leaks inherent in such a process and the potential impact on Vigil’s business of such leaks. As part of this discussion, the Board of Directors considered the prior interactions between Vigil management and other industry participants, including the results of the recent review of potential licensing opportunities. At the conclusion of this discussion, the Board of Directors determined that any outreach should include those parties that would be most likely to have interest in Vigil, be able to move decisively and have the ability to consummate a transaction of this size and nature. Accordingly, based on this criteria, the Board of Directors determined that Centerview should contact Party B and Party C with respect to their potential interest in an acquisition of Vigil, and that management should notify Sanofi that Vigil had received an unsolicited proposal from Party A as required under the ROFN Agreement. The Board of Directors then discussed Party A’s request for access to the Company’s virtual data room and authorized management to provide Party A with such access. Also during this meeting, the Board of Directors directed Vigil management to prepare long-range financial projections for Vigil as a standalone entity (without completing a strategic transaction with Party A or any other party) and related underlying assumptions.

On March 19, 2025, as directed by the Board of Directors, representatives of Centerview contacted representatives of Party B and Party C regarding their respective potential interest in an acquisition of the Company. Following these conversations, Party B conveyed to representatives of Centerview that Party B was not interested in an acquisition of Vigil at that time as Party B was not interested in acquiring VGL101, but Party B would be interested in a licensing transaction or an asset acquisition, and Party C conveyed to representatives of Centerview that Party C was not interested in pursuing a strategic transaction with Vigil at that time for various reasons, including that Party C was not interested in acquiring VGL101.

On March 20, 2025, Party D sent Vigil an unsolicited, written and non-binding proposal to acquire an exclusive, sublicensable, license from the Company to import, use, distribute, promote, and sell VGL101 in all member states of the European Union and the European Economic Area for $35.0 million paid upon execution of the license agreement, up to $295.0 million payable upon the occurrence of eight specified milestones, and annual royalty payments, which proposal was subject to the completion of Party D’s diligence, as Party D had only reviewed publicly available information regarding the Company, and assumed that the data from the ongoing Phase 2 IGNITE open-label clinical trial study would be sufficient for filing to and obtaining a Marketing Authorization from European authorities.

On March 21, 2025, Vigil provided representatives of Party A and its advisors access to a virtual data room to facilitate Party A’s corporate due diligence with respect to Vigil.

Also on March 21, 2025, as instructed by the Board of Directors, Dr. Magovčević-Liebisch contacted a senior representative of Sanofi during which Dr. Magovčević-Liebisch notified Sanofi, as required by the ROFN Agreement, that Vigil was engaging in discussions with a third party regarding a transaction pursuant to which Vigil would undergo a change of control, which notice was confirmed in writing in a letter delivered by Vigil to Sanofi on March 24, 2025.

On March 30, 2025, Vigil sent Party D a revised written and non-binding term sheet for Party D to acquire an exclusive, sublicensable, license from the Company to import, use, distribute, promote, and sell VGL101 in all member states of the European Union and the European Economic Area for $50.0 million paid upon execution of the license agreement, up to $305.0 million payable upon the occurrence of eight specified milestones, and annual royalty payments.

On April 2, 2025, Sanofi sent Vigil an unsolicited, written and non-binding proposal to acquire all of the outstanding shares of the Company for $6.00 in cash per share in upfront consideration and an additional $4.00 in

43

cash per share in the form of a CVR, which would be 100% payable upon the first commercial sale of VGL101 in the United States, provided that such sale occur no later than December 31, 2032 (the “April 2 Sanofi Proposal”).

On April 3, 2025, the Board of Directors held a meeting at which members of Vigil management and representatives of Centerview and Goodwin were present. At this meeting, members of Vigil management and representatives of Centerview reviewed the April 2 Sanofi Proposal, which, unlike the March 18 Party A Proposal, was not conditioned on any actions related to the Amgen License. The representatives of Centerview reported on the recent conversation with Party A’s senior representative regarding Party A’s potential interest in an acquisition of Vigil, including that Party A reiterated that the March 18 Party A Proposal was contingent upon Vigil and Amgen’s agreement to amend the Amgen License in a way that was suitable to Party A. The participants discussed that such amendment was not likely to be agreed upon by Amgen, and that the execution risk of a deal with Party A was therefore high. The representatives of Centerview provided feedback received from the various parties contacted, noting that Party B indicated it was only interested in a potential licensing or asset purchase transaction with the Company, and Party C indicated it was not interested in pursuing a potential transaction with the Company. The participants discussed that, for the same reasons discussed at the March 18 meeting (such as macro-economic conditions and financial trends, financing requirements, potential risks and benefits of outreach to counterparties and execution risks), they believed that a strategic transaction would be in the best interest of Company stockholders as compared to a licensing or asset purchase transaction. The representatives of Centerview then reviewed certain preliminary financial analyses related to the March 18 Party A Proposal and the April 2 Sanofi Proposal. The Board of Directors then discussed potential responses to Sanofi regarding the April 2 Sanofi Proposal and related process considerations. The participants discussed the expected timing for announcing the upcoming data read-out for the Phase 2 IGNITE open-label clinical trial, the low likelihood of finding a third party to finance or partner around VGL101 ahead of such read-out and the recent discussions with Party D. Following this discussion, the Board of Directors authorized Centerview to make a counteroffer to Sanofi of $8.00 per share in cash in upfront consideration and an additional $4.00 per share in cash in the form of CVRs, $2.00 of which would be payable upon the first commercial sale of VGL101 in the United States and $2.00 of which would be payable upon the initiation of a Phase 3 study for VG-3927.

Following this discussion, representatives of Goodwin again reviewed with the directors their fiduciary duties under Delaware law, and the process by which potentially conflicted board members, if any, would be recused from certain discussions and decisions to approve a final strategic transaction counterparty in the event that an actual or perceived conflict was determined to exist. Representatives of Goodwin also discussed the potential formation of a committee of the Board of Directors in order to facilitate the process in connection with any such transaction, and the scope of authority that the Board of Directors should consider granting to any such committee. Following this discussion, the Board of Directors resolved to establish, as a matter of convenience and efficiency (and not because of any actual or perceived conflicts of interests), a transaction committee of the Board of Directors (the “Transaction Committee”), consisting of Bruce Booth, DPhil, Cheryl Blanchard, PhD, Mary Thistle, and Stefan Vitorovic. The Board of Directors authorized the Transaction Committee to (i) oversee and provide direction to management and the Company’s advisors between meetings of the Board of Directors with respect to any potential transaction and any alternatives to any such transaction, including not engaging in a transaction, (ii) review, consider and evaluate all proposals that might be received by the Company in connection with any transaction, (iii) participate in and direct the negotiation of the terms and conditions of any transaction, and authorize, monitor and exercise general oversight on behalf of the Company of any and all agreements, proceedings and activities of the Company involving, responding to or relating to any transaction, (iv) consider, review and evaluate any other alternatives, (v) consult with and make such regular reports to the Board of Directors regarding the Transaction Committee’s deliberations or any other developments with respect to any transaction or other alternative, (vi) provide to the Board of Directors a recommendation as to whether the Board of Directors should pursue or abandon pursuit of any transaction or other alternative, or authorize any transaction or other alternative, in each case subject to applicable law, and as to the advisability of any definitive agreements related thereto and (vii) perform such other roles as may be requested by the Board of Directors from time to time.

44

Throughout the Transaction Committee’s evaluation of a potential strategic transaction, the Transaction Committee conducted formal meetings and provided feedback to transaction terms and documents, and its members also engaged in regular informal discussions with the Company’s management and legal and financial advisors, and with each other.

Following the conclusion of the April 3, 2025 meeting of the Board of Directors, and as authorized by the Board of Directors, a representative of Centerview contacted a senior representative of Sanofi and communicated the counteroffer of $8.00 per share in cash in upfront consideration and an additional $4.00 per share in cash in the form of CVRs.

On April 7, 2025, Sanofi sent Vigil a revised written non-binding proposal to acquire all of the outstanding shares of the Company for $8.00 per share in cash in upfront consideration and an additional $4.00 in cash per share in the form of CVRs, $2.00 of which would be payable upon the fifth patient dosed in the first Phase 3 study of VG-3927 for the treatment of Alzheimer’s disease, so long as such dosing occurred by December 31, 2031, and $2.00 of which would be payable upon the full approval by the FDA of VGL101 so long as such approval occurred by December 31, 2032 (the “April 7 Sanofi Proposal”).

Also on April 7, 2025, a senior representative of Sanofi contacted a representative of Centerview and communicated a request for the parties to agree to an exclusivity period that would provide for exclusive negotiations between the parties and categorized the April 7 Sanofi Proposal as Sanofi’s last, best and final offer.

Later on April 7, 2025, the Transaction Committee held a meeting at which other members of the Board of Directors, members of Vigil management, and representatives of Centerview and Goodwin were present. At this meeting, members of Vigil management and representatives of Centerview reviewed the April 7 Sanofi Proposal, which, unlike the March 18 Party A Proposal, was not conditioned on any actions related to the Amgen License, as well as the feedback Centerview received from a senior representative of Sanofi categorizing the April 7 Sanofi Proposal as Sanofi’s last, best and final offer and that Sanofi was only willing to proceed with further discussions on an exclusive basis. The representatives of Centerview then reviewed certain preliminary financial analyses related to the April 7 Sanofi Proposal. Following discussion, the Transaction Committee determined that the April 7 Sanofi Proposal would maximize value for the Vigil stockholders, offered less execution risk than the Proposal from Party A and directed Vigil’s management and its advisors to negotiate an exclusivity agreement with an exclusivity period ending no later than April 23, 2025, and to communicate to Party A that the parties needed to pause discussions and negotiations. Representatives of Goodwin then reviewed with the Transaction Committee the terms of Centerview’s engagement agreement. The Transaction Committee, pursuant to their delegated authority from the Board of Directors, thereafter authorized Vigil to finalize and execute the engagement letter with Centerview on substantially the terms presented at the meeting. On April 10, 2025, Vigil and Centerview entered into the related engagement letter.

On April 8, 2025, Vigil provided representatives of Sanofi and its advisors access to a virtual data room to facilitate Sanofi’s corporate due diligence with respect to Vigil. Thereafter, Sanofi sent a further list of requested due diligence items to Vigil. In addition to its review of the data room, during the days that followed, Sanofi and its advisors participated in multiple conference calls with senior management and representatives of Vigil as part of their due diligence investigation on topics including intellectual property, research and development, regulatory, commercial, manufacturing, human resources, tax, finance and accounting, and legal due diligence. Sanofi and its advisors continued to perform due diligence through the execution of the Merger Agreement.

Also on April 8, 2025, the Company entered into an amendment to a confidentiality agreement, dated October 11, 2024 with Sanofi, which confidentiality agreement was initially entered into by the Company and Sanofi for the purpose of evaluating a potential licensing or other partnering transaction between the parties, which confidentiality agreement was further amended on April 10, 2025, for the purpose of providing the protocols by which certain highly sensitive information of Vigil would be accessible to a specified subset of Sanofi’s advisors. The confidentiality agreement and amendments did not include a standstill provision.

45

Later on April 8, 2025, Freshfields US LLP, outside counsel to Sanofi (“Freshfields”), sent an initial draft of an exclusivity agreement to Goodwin, which provided for an exclusivity period terminable upon the earlier of two weeks from the date of execution of the exclusivity agreement or the execution and delivery of a definitive transaction agreement. Representatives of Goodwin sent Freshfields a revised draft of the exclusivity agreement that night, which provided that the exclusivity period would terminate upon the earliest of (i) 11:59 p.m. ET on the date that is 14 days from the date of the Company’s execution of the exclusivity agreement, (ii) Sanofi’s written (a) reduction of the purchase price in the April 7 Sanofi Proposal or (b) change in form of consideration in the April 7 Sanofi Proposal in a manner adverse to the Company or the Company’s equityholders, (iii) Sanofi’s notification that it is no longer interested in pursuing a strategic transaction with the Company, (iv) Sanofi’s public announcement or commencement of a public offer to acquire the Company’s securities or assets or (v) the execution and delivery of a definitive transaction agreement. On April 9, 2025, Sanofi and the Company executed the exclusivity agreement, which provided that the exclusivity period would expire as set forth above.

Also on April 9, 2025, at the direction of the Transaction Committee, representatives of Centerview had a call with a senior representative of Party A, during which representatives of Centerview informed the senior representative of Party A that the parties needed to pause discussions and negotiations.

On April 10, 2025, Party D sent Vigil a revised term sheet for Party D to acquire an exclusive, sublicensable, license from the Company to import, use, distribute, promote, and sell VGL101 in all member states of the European Union and the European Economic Area for $40.0 million paid upon execution of the license agreement, up to $300.0 million payable upon the occurrence of nine specified milestones, and annual royalty payments, which Vigil did not respond to at that time to in accordance with the exclusivity agreement between the Company and Sanofi.

On April 11, 2025, representatives of Freshfields provided Goodwin with an initial draft of the Merger Agreement for the proposed transaction, which provided for the transaction to be structured as a cash tender offer followed immediately by a back-end merger, and included, among other things, (i) a definition of “Material Adverse Effect,” which generally defines the standard for closing risk, without exceptions for regulatory, clinical or similar events or developments, (ii) the treatment of outstanding Company equity awards in connection with the Transactions, (iii) limitations on the efforts and obligations of Sanofi to obtain required antitrust approvals, (iv) the right of the Company to accept a Superior Offer after providing Sanofi with a right to match such proposal, (v) a termination fee equal to 4.5% of the equity value of the Company at the offered price (including the maximum value of the CVRs) payable by the Company in certain circumstances, (vi) a reverse termination fee of 4.5% of the equity value of the Company at the offered price (including the maximum value of the CVRs) payable by Sanofi in the event the Merger Agreement is terminated due to an order prohibiting the transaction that arises under the HSR Act equal to the value of the termination fee payable by the Company and (vii) the request for Dr. Booth, Atlas Venture, and an additional significant stockholder of the Company to execute a tender and support agreement in favor of Sanofi.

On April 14, 2025, the Transaction Committee held a meeting at which other members of the Board of Directors, members of Vigil management, and representatives of Centerview and Goodwin were present. Members of senior management updated the Board of Directors on the due diligence process, timing considerations and transaction status generally.

Also on April 14, 2025, representatives of Goodwin sent to representatives of Freshfields a revised Merger Agreement which provided, among other things, (i) a Termination Fee of 3.0%, (ii) a Reverse Termination Fee of 6.0%, (iii) revisions to the definition of Material Adverse Effect, and (iv) that Dr. Booth, Atlas Venture and Dr. Magovčević-Liebisch would execute a tender and support agreement in favor of Sanofi.

Also on April 14, 2025, representatives of Freshfields provided Goodwin with an initial draft of the form of tender and support agreement, which provided, among other things, that the signatories agree to tender the shares of Company common stock beneficially owned by them to the purchaser in the tender offer.

46

On April 15, 2025, representatives of Freshfields provided Goodwin with an initial draft of the CVR Agreement which provided, among other things, payment of additional $4.00 in cash per share in the form of CVRs, $2.00 of which would be payable upon the fifth patient dosed in the first Phase 3 study of VG-3927 for the treatment of Alzheimer’s disease, so long as such dosing occurred by December 31, 2031, and $2.00 of which would be payable upon the full approval by the FDA of VGL101 so long as such approval occurred by December 31, 2032.

On April 17, 2025, representatives of Freshfields provided Goodwin with a revised draft of the Merger Agreement which provided, among other things, (i) a Termination Fee of 4.0%, (ii) a Reverse Termination Fee of 5.0%, and (iii) revisions to the definition of Material Adverse Effect.

On April 18, 2025, representatives of Goodwin provided Freshfields with a revised draft of the Merger Agreement which provided, among other things, (i) a Termination Fee of 3.25%, (ii) a Reverse Termination Fee of 6.0%, and (iii) revisions to the definition of Material Adverse Effect.

Also on April 18, 2025, a senior representative of Sanofi called a representative of Centerview and informed Centerview that as a result of Sanofi’s due diligence exercise, Sanofi was not interested in acquiring VGL101, but reaffirmed the offered price per share in the April 7 Sanofi Proposal for Vigil and its small molecule TREM2 agonist platform, including VG-3927 (the “April 18 Proposal”).

Between April 18, 2025 and April 23, 2025, several meetings were held between members of Vigil management, representatives from Centerview and Goodwin, senior representatives from Sanofi, and representatives from Freshfields to discuss a potential path forward given the feedback Sanofi conveyed on April 18, 2025 that Sanofi was not interested in acquiring VGL101.

On April 22, 2025, the Board of Directors held a meeting at which representatives of Centerview and Goodwin were present. Dr. Magovčević-Liebisch provided an update regarding the April 18 Proposal and the possible solutions that had been discussed between the representatives and advisors of the Company and Sanofi on how to divest VGL101 from the transaction with Sanofi. The participants discussed the fact that the exclusivity period with Sanofi would expire on April 23, 2025 and noted that the March 18 Party A Proposal was conditioned upon Vigil’s and Amgen’s agreement to amend the Amgen License in a way that was suitable to Party A but which the Board of Directors believed might not be amenable to Amgen, which would present more execution risk than returning VGL101 to Amgen under the Amgen License. The participants also noted that the other parties that would most likely to be interested in and capable of pursuing a strategic transaction with the Company, Party B and Party C, had each indicated in March 2025 that they were not interested in pursuing a potential transaction to acquire the Company and that delaying the discussions with Sanofi to reengage with Party B and Party C could jeopardize the potential transaction with Sanofi, which the Board of Directors viewed as a significant risk given the low likelihood that Party B or Party C would have a renewed interest in a potential strategic transaction with the Company. The Board of Directors also discussed the meaningful premium being offered by Sanofi and how the challenging market conditions would make fundraising as a standalone company on acceptable terms, in the near term or at all particularly difficult if the transaction with Sanofi did not proceed. The Board of Directors also discussed the feedback Vigil and Centerview had received from potential strategic parties around VGL101, the expected timing for announcing the upcoming data read-out for the Phase 2 IGNITE open-label clinical trial, the low likelihood of finding a third party to finance or partner around VGL101 ahead of such read-out and that a return of the platform to Amgen would be the most prudent course of action for Vigil, its stockholders and for the VGL101 assets. Following discussion, the Board of Directors determined to continue to pursue a sale transaction with Sanofi, but on a non-exclusive basis, and directed the Company’s advisors to prepare a draft letter agreement to be signed by the Company and Amgen pursuant to which the rights to VGL101 would be returned to Amgen, and to contact Amgen to see whether Amgen would be amenable to executing such a letter agreement.

47

Also on April 22, 2025, as directed by the Board of Directors, Goodwin sent Freshfields a proposal of the terms by which the rights to VGL101 would be returned to Amgen. On April 23, 2025, Freshfields sent Goodwin comments to such terms.

On April 24, 2025, as directed by the Board of Directors, Dr. Magovčević-Liebisch had a call with a senior representative of Amgen, during which Dr. Magovčević-Liebisch asked the senior representative of Amgen whether Amgen would be amenable to discussing entering into a letter agreement to be signed by the Company and Amgen pursuant to which the rights to VGL101 would be returned to Amgen. The senior representative of Amgen confirmed that Amgen would be open to such discussions.

Between April 24, 2025 and May 21, 2025, Vigil and Goodwin conducted multiple conference calls and exchanged drafts of the Amgen Consent with Amgen, on the one hand, and with Sanofi and Freshfields, on the other hand, to finalize the terms by which VGL101 would be returned to Amgen prior to the closing of the transaction between Vigil and Sanofi. Among other items, the parties negotiated the scope of the intellectual property rights to be transferred and/or licensed to Amgen, timing considerations relative to the closing of the transaction between Vigil and Sanofi, and the process for the delivery of the Phase 2 data related to VGL101, the transfer of regulatory files for VGL101, and the process by which Amgen could elect to have the Company wind-down clinical studies of VGL101.

On April 26, 2025, Freshfields sent a revised draft of the Merger Agreement to Goodwin, which provided for the transaction to be structured as a single-step merger, rather than a cash tender offer followed immediately by a back-end merger, which change in structure Freshfields indicated was due to the additional time that would likely be needed to finalize the return of VGL101 to Amgen, which was included as a closing condition in the revised draft of the Merger Agreement. The draft Merger Agreement also provided, among other things, (i) a Termination Fee of 3.9%, (ii) a Reverse Termination Fee of 5.1%, and (iii) revisions to the definition of Material Adverse Effect.

Also on April 26, 2025, Freshfields sent a revised draft of the CVR Agreement to Goodwin, which reflected different payment milestones with respect to the CVRs than were included in the April 7 Sanofi Proposal, including changes to remove the milestone with respect to the full approval by the FDA of VGL101 by December, 2032 and to replace it with a milestone with respect to the first commercial sale of VG-3927.

On April 28, 2025, Goodwin sent a revised draft of the Merger Agreement to Freshfields. Thereafter, between April 28, 2025 and May 14, 2025, Goodwin, on behalf of Vigil, and Freshfields, on behalf of Sanofi, conducted a number of conference calls and exchanged drafts of the Merger Agreement. Among other items, the parties negotiated (i) the amounts of the Termination Fee and the Reverse Termination Fee, (ii) the definition of “Company Material Adverse Effect,” (iii) Vigil’s representations, warranties and interim operating covenants, (iv) the provisions relating to the rights of the Board of Directors to change its recommendation to stockholders with respect to the transaction with Sanofi and to accept a “Superior Offer,” and (v) the covenants regarding employee benefit matters applicable to Vigil employees generally. In addition, Vigil reached out to Sanofi regarding initial proposals for transaction bonus and severance programs for Vigil employees as authorized by the Compensation Committee of the Board of Directors, which included a transaction bonus pool and severance guidelines for non-executive employees to be honored by Sanofi for one year following the Closing.

Also on April 28, 2025, the Transaction Committee held a meeting at which other members of the Board of Directors, members of Vigil management, and representatives of Centerview and Goodwin were present. Dr. Magovčević-Liebisch and representatives of Goodwin provided an update to the Transaction Committee regarding the status of the transaction documents, including the proposed changes to the payment milestones for the CVRs and the status of the negotiations with each of Amgen and Sanofi regarding the Amgen Consent. The participants then discussed the fact that the exclusivity period with Sanofi expired on April 23, 2025 and discussed that the March 18 Party A Proposal was conditioned upon Vigil’s and Amgen’s agreement to amend the Amgen License in a way that was suitable to Party A (but that the Board of Directors believed may not be

48

amendable to Amgen), and that the other parties that would most likely to be interested in pursuing a strategic transaction with the Company, Party B and Party C, each indicated in March 2025 that they were not interested in acquiring the Company, and that Party B and Party C had each previously noted that they were not interested in acquiring VGL101. The participants also discussed the risk that Sanofi would discontinue negotiations if Sanofi believed the Company re-engaged other parties in discussions regarding a potential strategic transaction. Following discussion, the Transaction Committee determined to continue negotiations with Sanofi, as a sale transaction was in the best interest of Vigil’s stockholders given the current macro-economic conditions and financial trends and the fundraising that would be needed to support the Company’s operations as a standalone entity in the near future, and a sale transaction with Sanofi presented a lower execution risk than a sale transaction with the other most likely buyers.

Also on April 28, 2025, Goodwin sent Freshfields a revised draft of the form of voting and support agreement, which, among other things, reflected the change in structure from a two-step tender offer to a one-step merger with a stockholder vote.

On May 13, 2025, Vigil sent Party D a revised term sheet for Party D to acquire an exclusive, sublicensable, license from the Company to import, use, distribute, promote, and sell VGL101 in all member states of the European Union and the European Economic Area for $45.0 million paid upon execution of the license agreement, up to $300.0 million payable upon the occurrence of nine specified milestones, and annual royalty payments.

On May 14, 2025, a senior representative of Sanofi had a call with representatives of Centerview, during which the senior representative of Sanofi indicated that, although Sanofi was ascribing no value to the VGL101 assets, the complexities around the return of VGL101 to Amgen and the duration of the negotiation of the Amgen Consent were having a negative impact on the value that Sanofi was willing to pay to acquire Vigil, and the senior representative of Sanofi noted that Sanofi was considering terminating discussions with Vigil. The senior representative of Sanofi communicated that Sanofi would continue discussions with Vigil, but that the revised offer from Sanofi was still $8.00 per share in cash in upfront consideration but with only $2.00 in cash per share in the form of a CVR, which would be payable upon the approval of the first commercial sale of VG-3927 (the “May 14 Sanofi Proposal”). The senior representative of Sanofi further indicated that the May 14 Sanofi Proposal was contingent on the Company not making any material changes to the revised draft of the Merger Agreement that would be sent by Freshfields to Goodwin later that day, which would include a termination right in favor of Sanofi that would allow Sanofi to terminate the Merger Agreement if the Wind-Down Activities were not completed by a to be specified date.

Also on May 14, 2025, Freshfields sent a revised draft of the Merger Agreement to Goodwin, which provided for, among other things, (i) a termination right in favor of Sanofi that would allow Sanofi to terminate the Merger Agreement if, in the event of an Amgen Wind-Down Election, the Wind-Down Activities were not completed by a to be specified date, (ii) a closing condition in favor of Sanofi that would allow Sanofi to not close the Merger if, in the event of an Amgen Wind-Down Election, the Wind-Down Activities were not completed or whether or not an Amgen Wind-Down Election is made, the transfer to Amgen of all regulatory filings pursuant to the terms of the Amgen Consent did not occur, (iii) a Termination Fee of 3.75%, and (iv) a Reverse Termination Fee of 5.25%.

On May 15, 2025, the Transaction Committee held a meeting at which other members of the Board of Directors, members of Vigil management and representatives of Centerview and Goodwin were present. At this meeting, Dr. Magovčević-Liebisch and representatives of Centerview provided an update regarding the discussions between Sanofi and Vigil, including the feedback received that the decrease in the value of the CVRs in the offer price from a maximum of $4.00 per share of Company common stock to $2.00 per share of Company common stock was driven by the negative impact on the value that Sanofi was willing to pay to acquire Vigil due to the complexities around the return of VGL101 to Amgen and the duration of the negotiation of the Amgen Consent. Representatives from Centerview also reported on their conversation with Sanofi regarding the May 14

49

Sanofi Proposal, including that the representative from Sanofi noted that Sanofi considered terminating discussions with the Company, and that the May 14 Sanofi Proposal was contingent on the Company not making any material changes to the revised draft of the Merger Agreement that was sent by Freshfields to Goodwin on May 14, 2025, which included a termination right in favor of Sanofi that would allow Sanofi to terminate the Merger Agreement if the Amgen Wind-Down Activities were not completed by a to be specified date. Dr. Magovčević-Liebisch provided an update regarding Vigil management’s expected timing considerations to complete the Wind-Down Activities. Following discussion, representatives of Goodwin provided an update regarding the status of the negotiation of the Amgen Consent. The Transaction Committee then discussed potential responses to Sanofi regarding the May 14 Sanofi Proposal and related process considerations, including that (i) Sanofi had decreased the maximum value of the CVRs from up to $4.00 per share of Company common stock in the April 7 Sanofi Proposal, which, along with the $8.00 per share in cash in upfront consideration, Sanofi had previously characterized as the highest price that it was able to pay to acquire Vigil, to an offer of $2.00 per share of Company common stock in a CVR in the March 8th Proposal, which CVR decrease Sanofi had communicated was related to the Amgen Consent and the complexities around returning VGL101, (ii) Sanofi had substantially completed its due diligence and the Merger Agreement was substantially negotiated on terms reasonably acceptable to Vigil, (iii) Sanofi’s proposal was fully financed, (iv) there was a risk of Sanofi terminating discussions if the Board of Directors did not make a decision to proceed with a transaction at that time, (v) the low likelihood of finding a third party to finance or partner around VGL101, (vi) the partnering or fundraising that would be required if the Company continued as a standalone entity, and (vi) that a return of the platform to Amgen would be the most prudent course of action for Vigil, its stockholders and for the VGL101 assets. After discussion, the Transaction Committee determined that it was in the best interests of Vigil and its stockholders to proceed with a transaction with Sanofi at the price proposed in the May 14 Sanofi Proposal.

Also on May 15, 2025, Goodwin sent a revised draft of the Merger Agreement to Freshfields. Thereafter, between May 15, 2025 and May 21, 2025, Goodwin, on behalf of Vigil, and Freshfields, on behalf of Sanofi, conducted multiple conference calls and exchanged drafts of the Merger Agreement.

On May 16, 2025, Party D sent the Company a revised term sheet for Party D to acquire an exclusive, sublicensable, license from the Company to import, use, distribute, promote, and sell VGL101 in all member states of the European Union and the European Economic Area for $45.0 million paid upon execution of the license agreement, up to $300.0 million payable upon the occurrence of nine specified milestones, and annual royalty payments VGL101.

On May 17, 2025, the Board of Directors held a meeting at which members of Vigil management and representatives of Centerview and Goodwin were present. Dr. Magovčević-Liebisch provided an update on the status of the transaction documents, including the Amgen Consent. Representatives of Goodwin reminded the Board of Directors of its fiduciary duties under Delaware law in connection with a sale of the company for cash, which had been discussed with the Board of Directors throughout the process. Representatives of Goodwin then communicated that the Merger Agreement, the voting and support agreement and the CVR Agreement were near final form, but the Amgen Consent was still being negotiated. Representatives of Goodwin then reviewed the current terms of the transaction documents. Representatives of Centerview then reviewed with the Board of Directors Centerview’s preliminary financial analysis of the Merger Consideration.

Also at this meeting, the Board of Directors reviewed and discussed Vigil management’s standalone, long-range financial projections for 2025 through 2043, including the underlying assumptions and related risks (see the “Projections” in the section of this proxy statement titled “The Merger—Certain Unaudited Prospective Financial Information”). Following discussion of these matters, the Board of Directors approved the Projections for the reliance and use by Centerview in connection with providing its financial analysis and preparing any opinion as requested by the Board of Directors.

On May 20, 2025, representatives of Vigil and Goodwin had a call with representatives of Party D to discuss the proposal sent by Party D to Vigil on May 16, 2025. During the call, the parties noted that there

50

remained a number of material outstanding items regarding the potential license. Based on the call, and due to the conditions and assumptions included in Party D’s proposal, including that Party D’s proposal was subject to Party D’s diligence as Party D had only reviewed publicly available information and that Party D’s proposal assumed that the data from the ongoing Phase 2 IGNITE open-label clinical trial study would be sufficient for filing to and obtaining a Marketing Authorization from European authorities, the Company viewed the execution risk of a transaction with Party D as high.

During the day on May 21, 2025, representatives of Goodwin, on behalf of Vigil, and Freshfields, on behalf of Sanofi, finalized the open items in the Merger Agreement and the other transaction documents related to the Merger. Vigil, Goodwin, Amgen, Sanofi, and Freshfields also finalized the open items in the Amgen Consent.

Later on May 21, 2025, the Board of Directors, the Compensation Committee of the Board of Directors and the Transaction Committee held a joint meeting at which all members of the Board of Directors, members of Vigil management, as well as representatives of Centerview and Goodwin were in attendance. Dr. Magovčević-Liebisch provided a status update regarding negotiations with Sanofi. Representatives of Goodwin summarized the changes to the transaction documents, including the Merger Agreement, a proposed execution version of which was provided to and reviewed by the Board of Directors prior to the meeting, and the Amgen Consent since the May 17, 2025 meeting of the Board of Directors. Representatives of Goodwin also reviewed the relationship disclosure letter provided by Centerview regarding relationship between Centerview and Sanofi. Following review of this information, the Board of Directors determined that none of the matters set forth in the disclosure letter would limit Centerview’s ability to act effectively as financial advisor to Vigil. In addition, at the request of the Board of Directors, representatives of Centerview reviewed with the Board of Directors Centerview’s financial analysis of the Merger Consideration, and rendered to the Board of Directors an oral opinion, which was subsequently confirmed by delivery of a written opinion dated May 21, 2025, to the effect that, as of the date of such opinion and based on and subject to the matters set forth therein, including the various assumptions made, procedures followed, matters considered and qualifications and limitations upon the review undertaken by Centerview in preparing its opinion as set forth therein, the Merger Consideration to be paid to the holders of shares of Company common stock (other than (i) any shares of Company common stock held by the Company or any wholly-owned subsidiary of the Company (or held in the Company’s treasury), (ii) any shares of Company common stock held by Sanofi or any direct or indirect wholly owned subsidiary of Sanofi, (iii) any dissenting shares, and (iv) any shares of Company common stock held by any affiliate of the Company or Sanofi) pursuant to the Merger Agreement was fair from a financial point of view to such holders (for a detailed discussion of Centerview’s opinion, please see the section of this proxy statement titled “Opinion of Centerview Partners LLC”). Following additional discussion and consideration of the Merger Agreement, the Merger and the other transactions contemplated by the Merger Agreement (including the factors described under the heading “Recommendation of the Board of Directors; Reasons for the Merger”), the Board of Directors unanimously (i) determined that the Merger Agreement and the Transactions, including the Merger, are advisable and fair to, and in the best interest of, the Company and its stockholders, (ii) approved the execution, delivery and performance by the Company of the Merger Agreement and the consummation by the Company of the Transactions, including the Merger, (iii) directed that the Merger Agreement be submitted to the stockholders of the Company for their adoption at the Special Meeting, (iv) resolved to recommend that the stockholders of the Company adopt the Merger Agreement and approve the Merger and (v) approved and declared advisable the Voting and Support Agreement and the transactions contemplated thereby.

Thereafter, in the evening of May 21, 2025, Vigil, Sanofi, and Merger Sub executed the Merger Agreement.

Thereafter, later in the evening of May 21, 2025, Vigil and Sanofi each issued a press release announcing the execution of the Merger Agreement.

Recommendation of the Board of Directors; Reasons for the Merger

The Board of Directors, after careful review and consideration and consultation with its financial and legal advisors, and upon the unanimous recommendation of the Transaction Committee, unanimously (i) determined

51

that the Merger Agreement and the Transactions, including the Merger, are advisable and fair to, and in the best interest of, the Company and its stockholders, (ii) approved the execution, delivery and performance by the Company of the Merger Agreement and the consummation by the Company of the Transactions, including the Merger, (iii) directed that the Merger Agreement be submitted to the stockholders of the Company for their adoption at the Special Meeting, (iv) recommended that the stockholders of the Company adopt the Merger Agreement and approve the Merger and (v) approved and declared advisable the Voting and Support Agreements and the transactions contemplated thereby. Accordingly, the Board of Directors unanimously recommends that the Company stockholders vote “FOR” the Transaction Proposal and “FOR” the Adjournment Proposal.

In evaluating the Merger Agreement and the Transactions, including the Merger, each of the Transaction Committee and the Board of Directors consulted with the Company’s management and legal and financial advisors. In the course of reaching its determination that the terms of the Merger Agreement and the Transactions, including the Merger, are advisable and fair to the Company’s stockholders, and in the best interests of, the Company and its stockholders and to recommend that the Company’s stockholders vote in favor of the Transaction Proposal, each of the Transaction Committee and the Board of Directors reviewed, evaluated, and considered a significant amount of information and numerous factors and benefits of the Merger, each of which the Transaction Committee and the Board of Directors believed supported its determination and recommendation. As a result, for the reasons set forth below, the Board of Directors unanimously recommends, upon the unanimous recommendation of the Transaction Committee, that the stockholders of the Company vote in favor of the Transaction Proposal:

Premium to Market Price. Each of the Transaction Committee and the Board of Directors considered:

Certainty of Upfront Value. Each of the Transaction Committee and the Board of Directors considered that the consideration to be paid in the Merger will consist primarily of upfront cash, which provides liquidity and certainty of value to the Company’s stockholders. Taking into account the various risks that the Company would face by continuing to pursue its current business and financial plans, each of the Transaction Committee and the

52

Board of Directors believed that this certainty of value was compelling compared to the uncertain long-term value creation potential of the Company’s business.

Opportunity to Realize Additional Value. Each of the Transaction Committee and the Board of Directors considered the fact that, in addition to the upfront cash consideration of $8.00, holders of Company common stock have an opportunity to realize additional value if the Milestone (as defined below) set forth in the CVR Agreement (as defined below) is achieved within the time period prescribed therein, through an additional cash payment of $2.00, net to the holder and without interest thereon, per CVR. Each of the Transaction Committee and the Board of Directors considered that Parent and its affiliates (i) are obligated to use Diligent Efforts (as defined in the CVR Agreement) to achieve the Milestone by December 31, 2035 and (ii) have extensive resources, capabilities and experience in biopharmaceutical product development and commercialization, particularly as such experience, capabilities and resources relate to the potential achievement of the Milestone compared to the Company’s stand-alone capabilities.

The Company’s Operating and Financial Condition and Prospects. Each of the Transaction Committee and the Board of Directors considered the Company’s operating and financial performance and its prospects, including certain financial projections for the Company prepared by Company’s management, which reflect an application of various assumptions of management, as further discussed in the section titled “The Merger—Certain Unaudited Prospective Financial Information.” Each of the Transaction Committee and the Board of Directors considered the Company’s business and financial plans, including the risks and uncertainties associated with achieving and executing on Company’s business and financial plans in the short- and long-term, as well as the general risks of market conditions that could reduce the price of the Company common stock. Among the potential risks and uncertainties identified by the Transaction Committee and the Board of Directors were:

53

Potential Strategic Alternatives. Each of the Transaction Committee and the Board of Directors reviewed the possible alternatives to the Merger, including the possibility of continuing to operate the Company as an independent company, the potential benefits and risks of these alternatives to the Company and its stockholders and the timing and likelihood of effecting such alternatives. Taking into account the risks of execution as well as business, competitive, industry and market risks, each of the Transaction Committee and the Board of Directors considered that none of the possible alternatives were reasonably likely to present superior opportunities for the Company to create greater value for the Company’s stockholders.

VGL101 Development Risks. Each of the Transaction Committee and the Board of Directors considered the status and prospects for the Company’s current product candidates, programs and pipeline, in particular, VGL101. Each of the Transaction Committee and the Board of Directors considered the risk that future development of VGL101 may be limited or may not be possible at all. Each of the Transaction Committee and the Board of Directors further considered (i) the low likelihood of finding a third party to finance or partner around VGL101 ahead of the Phase 2 IGNITE data read-out, which was expected in the second quarter of 2025, particularly in light of feedback received from potential strategic parties, (ii) the terms of the Amgen Consent (as defined below) and (iii) the Company’s ability to, pursuant to the terms of the Amgen Consent, return VGL101 to Amgen as the original licensor.

Negotiation Process. Each of the Transaction Committee and the Board of Directors considered the fact that the terms of the Merger Agreement were the result of robust arm’s-length negotiations conducted by the Company with the knowledge and at the direction of the Board of Directors (including through the Transaction Committee) and with the assistance of its financial and legal advisors. Each of the Transaction Committee and the Board of Directors also considered the enhancements that the Company and its advisors were able to obtain as a result of robust arm’s-length negotiations with Parent, including the increase in the upfront cash consideration offered by Parent from the time of its initial expression of interest to the end of the negotiations and the inclusion of provisions in the Merger Agreement that increase the likelihood of completing the Transaction. Each of the Transaction Committee and the Board of Directors believes, based on the Company’s negotiations with Parent and input from the Company’s management, that the Merger Consideration was the highest amount of consideration per share of Company common stock that Parent was willing to pay and that the Merger Agreement contained the most favorable terms on significant points to the Company to which Parent was willing to agree.

Potentially Interested Counterparties. Each of the Transaction Committee and the Board of Directors considered the process conducted by the Company, with the assistance of representatives of Centerview, to identify potential buyers taking into account the expected interest of such parties in neurological pharmaceuticals generally, their financial capability to consummate a transaction of this size and nature, regulatory considerations and their ability to move quickly, decisively and efficiently in a process. In particular, each of the Transaction Committee and the Board of Directors considered the recent discussions conducted by the Company with other industry participants and the outcome of those discussions, including the proposal by a potential strategic counterparty with terms contingent upon an amendment to the Amgen License that was not likely to be agreed upon by Amgen and potential counterparties who were only interested in pursuing potential licensing or asset purchase transactions. Each of the Transaction Committee and the Board of Directors also considered that should any potential counterparty be interested in pursuing a transaction on terms more favorable to the Company and its stockholders than those contemplated by the Merger Agreement, such counterparty would be able to pursue such an offer for the Company despite the Company’s entry into an Merger Agreement with Parent.

Business Reputation of Parent. Each of the Transaction Committee and the Board of Directors considered the business reputation and capabilities of Parent and its management and the substantial financial resources of Parent, which the Transaction Committee and the Board of Directors believed supported the conclusion that a transaction with Parent was likely to be completed in a timely and orderly manner.

54

Voting and Support Agreements. Each of the Transaction Committee and the Board of Directors considered that the Supporting Stockholders that held, in the aggregate, approximately 16.2% of the total voting power of the outstanding shares of Company common stock as of May 21, 2025, entered into Voting and Support Agreements obligating each of them during the term of such agreement, among other things, to vote their shares of Company common stock in favor of the Merger Agreement, the Merger and the other transactions contemplated by the Merger Agreement, and, subject to certain exceptions, not to transfer any of their shares of Company common stock that are subject to the Voting and Support Agreements. Each of the Transaction Committee and the Board of Directors further considered that the Voting and Support Agreements would terminate in certain circumstances, including upon a valid termination of the Merger Agreement or with notice following an adverse amendment to the Merger Agreement made without consent of the Supporting Stockholder.

Opinion of Financial Advisor. The Board of Directors considered the oral opinion of Centerview rendered to the Board of Directors, including all members of the Transaction Committee, on May 21, 2025, which was subsequently confirmed by delivery of a written opinion dated such date, that, as of such date and based upon and subject to the various assumptions made, procedures followed, matters considered, and qualifications and limitations upon the review undertaken by Centerview in preparing its opinion, the Merger Consideration to be paid to the holders of shares of Company common stock (other than Excluded Shares) pursuant to the Merger Agreement was fair, from a financial point of view, to such holders, as more fully described in the section of this proxy statement titled “The Merger—Opinion of Centerview Partners LLC.”

The Merger Agreement; Ability to Consider, Receive and Respond to Unsolicited Proposals; Receive a Reverse Termination Fee in the Event the Merger Agreement is Terminated Under Certain Circumstances. Each of the Transaction Committee and the Board of Directors considered the provisions of the Merger Agreement, including (i) the ability of the Company under certain circumstances to entertain unsolicited proposals for an acquisition that constitute or could reasonably be expected to lead to an offer that is superior to the Merger prior to the approval of the Company stockholders, (ii) the ability of the Board of Directors under certain circumstances to withdraw or modify its recommendation that the Company’s stockholders vote in favor of the Transaction Proposal and to terminate the Merger Agreement in order to accept a Superior Offer (as defined below) and enter into a definitive agreement with respect to such Superior Offer, (iii) the $22,246,157 Termination Fee payable by the Company under certain circumstances, which the Transaction Committee and the Board of Directors believed was reasonable relative to termination fees in transactions of a similar size, would not likely preclude competing bids and (iv) the $31,144,620 Reverse Termination Fee payable by Parent in the event the Merger Agreement is terminated as a result of certain conditions related to antitrust laws not being satisfied.

Conditions to the Consummation of the Merger; Likelihood of Completion. Each of the Transaction Committee and the Board of Directors considered the likelihood of completing the Merger, particularly in light of the terms of the Merger Agreement, including (i) the conditions to the Merger being specific and limited, (ii) the exceptions contained within the “Material Adverse Effect” definition, which generally defines the standard for closing risk, (iii) the likelihood of obtaining regulatory approvals and (iv) the End Date (as defined below) under the Merger Agreement, which is anticipated to allow for sufficient time to consummate the Merger. Each of the Transaction Committee and the Board of Directors also considered the fact that there is no financing condition to the completion of the Merger.

Dissenters’ Rights. Each of the Transaction Committee and the Board of Directors considered the availability of statutory dissenters’ rights to the Company’s stockholders who object to the Merger and otherwise comply with all required procedures under Section 262.

Product Development and Commercialization Risks. Each of the Transaction Committee and the Board of Directors assessed the Company’s ability to develop and commercialize products as a standalone company in order to create stockholder value in excess of the Merger Consideration, given the risks and uncertainties in the Company’s business, including that:

55

Independence. The Transaction Committee consists solely of independent and disinterested directors of the Board of Directors. None of members of the Transaction Committee were or are officers or employees of the Company.

Stockholder Approval. Each of the Transaction Committee and the Board of Directors considered that approval of the Transaction Proposal requires the affirmative vote of the holders of a majority of the outstanding shares of Company common stock entitled to vote on the Transaction Proposal.

In the course of its deliberations, the Board also considered a variety of material risks and other countervailing factors related to entering into the Merger Agreement, including, but not limited to, the following (which are not necessarily presented in order of relative importance):

56

The foregoing discussion of the information and factors considered by the Transaction Committee and the Board of Directors in reaching its conclusions and recommendations is not intended to be exhaustive but includes the material reasons and factors considered by the Transaction Committee and the Board of Directors. In view of the wide variety of reasons and factors considered, each of the Transaction Committee and the Board of Directors did not find it practicable to, and did not, quantify, rank or otherwise assign any relative or specific weights to the various specific factors considered in reaching its determination and making its recommendation. In addition, each of the Transaction Committee and the Board of Directors did not reach any specific conclusion with respect to any of the factors or reasons considered. Instead, each of the Transaction Committee and the Board of Directors conducted an overall review of the factors and reasons described above and determined that, in the aggregate, the potential benefits considered outweighed the potential risks or possible negative consequences of the Merger.

The foregoing discussion of the reasoning of the Board of Directors (including the Transaction Committee) and certain information presented in this section is forward-looking in nature and, therefore, the information should be read in light of the factors discussed in the section of this proxy statement titled “Cautionary Statement Regarding Forward-Looking Statements.” For the reasons described above, and in light of other factors that the Transaction Committee and the Board of Directors believed were appropriate to consider, the Board of Directors

57

approved the Merger Agreement and the Transactions, including the Merger, and recommends that the Company’s stockholders vote in favor of the Transaction Proposal.

Opinion of Centerview Partners LLC

The Company retained Centerview as financial advisor to the Company in connection with the Merger. In connection with this engagement, the Board of Directors requested that Centerview evaluate the fairness, from a financial point of view, to the holders of shares of Company common stock (other than Excluded Shares) of the Merger Consideration proposed to be paid to such holders pursuant to the Merger Agreement. On May 21, 2025, Centerview rendered to the Board of Directors its oral opinion, which was subsequently confirmed by delivery of a written opinion dated May 21, 2025, that, as of such date and based upon and subject to the assumptions made, procedures followed, matters considered, and qualifications and limitations upon the review undertaken by Centerview in preparing its opinion, the Merger Consideration proposed to be paid to the holders of shares of Company common stock (other than Excluded Shares) pursuant to the Merger Agreement was fair, from a financial point of view, to such holders.

The full text of Centerview’s written opinion, dated May 21, 2025, which describes the assumptions made, procedures followed, matters considered, and qualifications and limitations upon the review undertaken by Centerview in preparing its opinion, is attached as Annex B to this proxy statement and is incorporated herein by reference. The summary of the written opinion of Centerview set forth below is qualified in its entirety by the full text of Centerview’s written opinion attached as Annex B to this proxy statement. Centerview’s financial advisory services and opinion were provided for the information and assistance of the Board of Directors (in their capacity as directors and not in any other capacity) in connection with and for purposes of its consideration of the Merger and Centerview’s opinion addressed only the fairness, from a financial point of view, as of the date thereof, to the holders of shares of Company common stock (other than Excluded Shares) of the Merger Consideration to be paid to such holders pursuant to the Merger Agreement. Centerview’s opinion did not address any other term or aspect of the Merger Agreement or the Merger and does not constitute a recommendation to any stockholder of the Company as to how such stockholder or other person should vote with respect to the Merger or otherwise act with respect to the Merger or any other matter.

You should carefully read the full text of Centerview’s written opinion in its entirety for a description of the assumptions made, procedures followed, matters considered, and qualifications and limitations upon the review undertaken by Centerview in preparing its opinion.

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

58

Centerview also participated in discussions with members of the senior management and representatives of the Company regarding their assessment of the Internal Data, and conducted such financial studies and analyses and took into account such information as Centerview deemed appropriate.

Centerview assumed, without independent verification or any responsibility therefor, the accuracy and completeness of the financial, legal, regulatory, tax, accounting and other information supplied to, discussed with, or reviewed by Centerview for purposes of its opinion and, with the consent of the Board of Directors, Centerview relied upon such information as being complete and accurate. In that regard, Centerview assumed, at the Board of Directors’ direction, that the Internal Data (including, without limitation, the Projections) were reasonably prepared on bases reflecting the best currently available estimates and judgments of the management of the Company as to the matters covered thereby and Centerview relied, at the direction of the Board of Directors, on the Internal Data for purposes of Centerview’s analysis and opinion. Centerview expressed no view or opinion as to the Internal Data or the assumptions on which it was based. In addition, at the Company’s direction, Centerview did not make any independent evaluation or appraisal of any of the assets or liabilities (contingent, derivative, off-balance-sheet or otherwise) of the Company, nor was Centerview furnished with any such evaluation or appraisal, and was not asked to conduct, and did not conduct, a physical inspection of the properties or assets of the Company. Centerview assumed, at the direction of the Board of Directors, that the final executed Merger Agreement and the final executed CVR Agreement would not differ in any respect material to Centerview’s analysis or opinion from the execution version of the Merger Agreement and the final form of CVR Agreement attached thereto reviewed by Centerview. Centerview also assumed, at the direction of the Board of Directors, that the Merger will be consummated on the terms set forth in the Merger Agreement and the CVR Agreement and in accordance with all applicable laws and other relevant documents or requirements, without delay or the waiver, modification or amendment of any term, condition or agreement, the effect of which would be material to Centerview’s analysis or Centerview’s opinion and that, in the course of obtaining the necessary governmental, regulatory and other approvals, consents, releases and waivers for the Merger, no delay, limitation, restriction, condition or other change will be imposed, the effect of which would be material to Centerview’s analysis or Centerview’s opinion. Centerview did not evaluate and did not express any opinion as to the solvency or fair value of the Company, or the ability of the Company to pay its obligations when they come due, or as to the impact of the Merger on such matters, under any state, federal or other laws relating to bankruptcy, insolvency or similar matters. Centerview is not a legal, regulatory, tax or accounting advisor, and Centerview expresses no opinion as to any legal, regulatory, tax or accounting matters.

Centerview expressed no view as to, and its opinion did not address, the Company’s underlying business decision to proceed with or effect the Merger, or the relative merits of the Merger as compared to any alternative business strategies or transactions that might be available to the Company or in which the Company might engage. Centerview’s opinion was limited to and addressed only the fairness, from a financial point of view, as of the date of Centerview’s written opinion, to the holders of shares of Company common stock (other than Excluded Shares) of the Merger Consideration to be paid to such holders pursuant to the Merger Agreement. Centerview was not asked to, and Centerview did not express any view on, and its opinion did not address, any other term or aspect of the Merger Agreement, the CVR Agreement, or the Merger, including, without limitation, the structure or form of the Merger, the form or terms of the CVR with respect to transferability, illiquidity or otherwise or any other agreements or arrangements contemplated by the Merger Agreement or entered into in connection with or otherwise contemplated by the Merger, including, without limitation, the Amgen Consent (as defined in the Merger Agreement) and all transactions, arrangements, and actions contemplated thereby, the fairness of the Merger or any other term or aspect of the Merger to, or any consideration to be received in connection therewith by, or the impact of the Merger on, the holders of any other class of securities, creditors or other constituencies of the Company or any other party. In addition, Centerview expressed no view or opinion as to the fairness (financial or otherwise) of the amount, nature or any other aspect of any compensation to be paid

59

or payable to any of the officers, directors or employees of the Company or any party, or class of such persons in connection with the Merger, whether relative to the Merger Consideration to be paid to the holders of shares of Company common stock pursuant to the Merger Agreement or otherwise. Centerview’s opinion was necessarily based on financial, economic, monetary, currency, market and other conditions and circumstances as in effect on, and the information made available to Centerview as of, the date of Centerview’s written opinion, and Centerview does not have any obligation or responsibility to update, revise or reaffirm its opinion based on circumstances, developments or events occurring after the date of Centerview’s written opinion. Centerview’s opinion does not constitute a recommendation to any stockholder of the Company or any other person as to how such stockholder or other person should vote with respect to the Merger or otherwise act with respect to the Merger or any other matter. Centerview’s financial advisory services and its opinion were provided for the information and assistance of the Board of Directors (in their capacity as directors and not in any other capacity) in connection with and for purposes of its consideration of the Merger. The issuance of Centerview’s opinion was approved by the Centerview Partners LLC Fairness Opinion Committee.

Summary of Centerview Financial Analysis

The following is a summary of the material financial analyses prepared and reviewed with the Board of Directors in connection with Centerview’s opinion, dated May 21, 2025. The summary set forth below does not purport to be a complete description of the financial analyses performed or factors considered by, and underlying the opinion of, Centerview, nor does the order of the financial analyses described represent the relative importance or weight given to those financial analyses by Centerview. Centerview may have deemed various assumptions more or less probable than other assumptions, so the reference ranges resulting from any particular portion of the analyses summarized below should not be taken to be Centerview’s view of the actual value of the Company. In performing its analyses, Centerview made numerous assumptions with respect to industry performance, general business and economic conditions and other matters, many of which are beyond the control of the Company or any other parties to the Merger. None of the Company, Parent, Merger Sub or Centerview or any other person assumes responsibility if future results are materially different from those discussed. Any estimates contained in these analyses are not necessarily indicative of actual values or predictive of future results or values, which may be significantly more or less favorable than as set forth below. In addition, analyses relating to the value of the Company do not purport to be appraisals or reflect the prices at which the Company may actually be sold. Accordingly, the assumptions and estimates used in, and the results derived from, the financial analyses are inherently subject to substantial uncertainty. Except as otherwise noted, the following quantitative information, to the extent that it is based on market data, is based on market data as it existed on or before May 20, 2025 (the last trading day before the date on which the transaction was publicly announced) and is not necessarily indicative of current market conditions.

Analysis of Merger Consideration

Centerview conducted an analysis of the Merger Consideration to be paid to the holders of shares of Company common stock (other than Excluded Shares) pursuant to the Merger Agreement and the CVR Agreement. Such Merger Consideration is equal, on a per share of Company common stock basis, to an amount in cash equal to $8.00, without interest, taken together (and not separately) with one CVR representing the right to receive $2.00, without interest, upon achievement, if any, of the Milestone in accordance with the terms and conditions of the CVR Agreement as described more fully in the section of this proxy statement titled “The Merger Agreement—Contingent Value Rights Agreement.”

For analytical purposes, assuming that for one CVR, the holder thereof receives a payment equal to $2.00 upon the achievement of the Milestone, based solely on the assessments of the Company’s management as to the probability of realizing the Milestone Payment (as defined in the CVR Agreement) and the estimated timing of achievement of the Milestone, and discounting the probability-adjusted Milestone Payment under the CVR Agreement back to the valuation date of June 30, 2025 using the midpoint of a range of discount rates from

60

15.0% to 16.5% based on Centerview’s analysis of the Company’s weighted average cost of capital, Centerview calculated an illustrative risk-adjusted net present value for one CVR of $0.14.

Solely for purposes of the financial analyses summarized in this section below, the term “Implied Consideration Value” refers to an aggregate assumed implied per share value of $8.14 per share of Company common stock, equal, on a per share basis, to $8.00 upfront consideration plus the illustrative risk-adjusted net present value of the CVR of $0.14, based on the midpoint of the range of discount rates, as set forth above. However, there is no guarantee that any of the conditions for the Milestone Payment pursuant to the CVR Agreement will be satisfied, and if satisfied, when such conditions will be satisfied.

Discounted Cash Flow Analysis

Centerview performed a discounted cash flow analysis of the Company based on the Projections, which reflect certain assumptions and projected future financing needs of the Company. A discounted cash flow analysis is a traditional valuation methodology used to derive a valuation of an asset or set of assets by calculating the “present value” of estimated future cash flows of the asset or set of assets. “Present value” refers to the current value of future cash flows and is obtained by discounting those future cash flows by a discount rate that takes into account macroeconomic assumptions and estimates of risk, the opportunity cost of capital, expected returns and other appropriate factors.

In performing this analysis, Centerview calculated a range of equity values for the shares of Company common stock by (a) discounting to present value, as of June 30, 2025, using discount rates ranging from 15.0% to 16.5% (based on Centerview’s analysis of the Company’s weighted average cost of capital) and using a mid-year convention: (i) the forecasted risk-adjusted, after-tax unlevered free cash flows of the Company over the period beginning on July 1, 2025 and ending on December 31, 2043, as set forth in the Projections, (ii) an implied terminal value of the Company, calculated by Centerview by assuming that (as directed by Company management) the Company’s unlevered free cash flows would decline in perpetuity after December 31, 2043 at a rate of free cash flow decline of 50% year over year, (iii) tax savings from usage of the Company’s estimated federal net operating losses, as set forth in the Projections, and (iv) the net impact of assumed equity raises in 2025 and the period from 2026 through 2030, as set forth in the Projections, and (b) adding to the foregoing results the Company’s cash balance of $67 million (including investments) as of June 30, 2025, as set forth in the Internal Data.

Centerview then calculated a range of implied equity values per share of Company common stock by dividing the result of the foregoing calculations by the Company’s fully diluted outstanding shares of Company common stock of approximately 91.8 million to 92.8 million calculated on a treasury stock method basis (taking into account outstanding stock options, restricted stock units, pre-funded warrants and near-term equity financing and the impact of equity raises in 2025) as of May 20, 2025 (the last trading day before the date on which the transaction was publicly announced) and as set forth in the Internal Data. The resulting range of implied equity values per share of Company common stock was $4.40 to $5.40, rounded to the nearest $0.05. Centerview then compared this range to the Implied Consideration Value of $8.14 per share to be paid to the holders of shares of Company common stock (other than Excluded Shares) pursuant to the Merger Agreement and the CVR Agreement.

Other Factors

Centerview noted for the Board of Directors certain additional factors solely for reference and informational purposes only, including, among other things, the following:

61

General

The preparation of a financial opinion is a complex analytical process involving various determinations as to the most appropriate and relevant methods of financial analysis and the application of those methods to the particular circumstances and, therefore, a financial opinion is not readily susceptible to summary description. In arriving at its opinion, Centerview did not draw, in isolation, conclusions from or with regard to any factor or analysis that it considered. Rather, Centerview made its determination as to fairness on the basis of its experience and professional judgment after considering the results of all of the analyses.

Centerview’s financial analyses and opinion were only one of many factors taken into consideration by the Board of Directors in its evaluation of the Merger. Consequently, the analyses described above should not be viewed as determinative of the views of the Board of Directors or management of the Company with respect to the Merger Consideration or as to whether the Board of Directors would have been willing to determine that a different consideration was fair. The consideration for the Merger was determined through arm’s-length negotiations between the Company and Parent and was approved by the Board of Directors. Centerview provided advice to the Company during these negotiations. Centerview did not, however, recommend any specific amount of consideration to the Company or the Board of Directors or that any specific amount of consideration constituted the only appropriate consideration for the Merger.

Centerview is a securities firm engaged directly and through affiliates and related persons in a number of investment banking, financial advisory and merchant banking activities. In the two years prior to the date of its written opinion, except for its current engagement, Centerview had not been engaged to provide financial advisory or other services to the Company, and Centerview did not receive any compensation from the Company during such period. In the two years prior to the date of Centerview’s written opinion, Centerview’s UK affiliate, Centerview Partners UK LLP (“Centerview UK”), provided, and is currently providing, financial advisory services unrelated to the Company to Parent, in connection with certain strategic matters, including the sale of its autoimmune drug, Enjaymo, to Recordati in 2024, and Centerview UK received between $10 million and $15 million in compensation from Parent for the financial advisory services that it provided in connection with the Enjaymo transaction. Centerview UK has not signed an engagement agreement with Parent relating to the other financial services that it is currently providing to Parent, but may do so in the future. Accordingly, it is uncertain whether Centerview UK will receive any fees in relation to such other financial services that it is currently providing to Parent and any fees that might be received in connection with such services cannot be quantified at this time. Centerview may provide financial advisory and other services to or with respect to the Company, Parent or their respective affiliates in the future, for which Centerview may receive compensation. Certain (i) of Centerview’s and its affiliates’ directors, officers, members and employees, or family members of such persons, (ii) of Centerview’s affiliates or related investment funds and (iii) investment funds or other

62

persons in which any of the foregoing may have financial interests or with which they may co-invest, may at any time acquire, hold, sell or trade, in debt, equity and other securities or financial instruments (including derivatives, bank loans or other obligations) of, or investments in, the Company, Parent, or any of their respective affiliates, or any other party that may be involved in the Merger.

The Company selected Centerview as its financial advisor in connection with the Merger based on Centerview’s reputation and experience in the biopharmaceutical industry and expertise and qualifications in transactions of this nature. Centerview is an internationally recognized investment banking firm that has substantial experience in transactions similar to the Merger.

In connection with Centerview’s services as the financial advisor to the Company, the Company has agreed to pay Centerview an aggregate fee of approximately $14.3 million, $1 million of which was payable upon the rendering of Centerview’s opinion and $13.3 million of which is payable contingent upon consummation of the Merger. In addition, the Company has agreed to reimburse certain of Centerview’s expenses arising, and to indemnify Centerview against certain liabilities that may arise, out of Centerview’s engagement.

Certain Unaudited Prospective Financial Information

The Company does not, as a matter of course, publicly disclose forecasts or projections as to future performance, earnings or other financial results due to the inherent unpredictability of projections and their underlying assumptions and estimates and the inherent difficulty of accurately predicting financial performance for future periods. However, in connection with its strategic planning process and at the direction of the Board of Directors, the Company’s management prepared long-range projections, reflecting the best currently available estimates and judgments of the Company management’s on a risk-adjusted basis for the third and fourth quarters of fiscal year 2025 through fiscal year 2043 of the Company on a stand-alone basis and without giving effect to the Transactions, including the Merger (the “Projections”). These Projections reflect a risk- and probability-adjusted outlook and were based on certain internal assumptions about the probability of commercial success of certain of the Company’s product candidates and programs, including with respect to VGL101 and VG-3927, potential licensing arrangements and strategic partnerships with respect to the Company’s product candidates and programs, epidemiology, sales ramp, market size, market share, market penetration, pricing, reimbursement, duration of therapy, competition, market exclusivity, estimated costs and expenses, effective tax rate and utilization of net operating losses, ability to raise future capital, and other relevant factors, all of which are difficult to predict and many of which are beyond the Company’s control, relating to the Company and its product candidates. The Projections were developed solely using the information available to the Company’s management at the time the Projections were created and are based on estimates, assumptions and judgments made by the Company’s management at the time of their preparation and speak only as of such time.

The Projections were provided to and considered by the Board of Directors and the Transaction Committee in connection with their respective evaluations of the Merger in comparison to the Company’s other strategic alternatives. The Projections also were provided to Centerview, and the Board of Directors directed Centerview to use the Projections for purposes of rendering of its opinion to the Board of Directors and in performing the related financial analysis as described in the section of this proxy statement titled “The Merger—Opinion of Centerview Partners LLC”. The Projections were not provided to Parent. The Projections were the only financial projections with respect to the Company used by Centerview in performing its financial analysis.

Cautionary Note About the Projections

The Projections, while necessarily presented with numerical specificity, are necessarily based on numerous variables and assumptions that are inherently uncertain, including as a result of the Company not currently having any marketed products, and many of which are beyond the Company’s control. The Projections are based on estimates, assumptions and judgments made by the Company’s management, based on information available at the time the Projections were developed, with respect to industry performance and competition, regulatory

63

conditions, general business, economic, market and financial conditions, and matters specific to the Company’s product candidates, all of which are difficult to predict and many of which are beyond the Company’s control. As a result, there can be no assurance that the Projections accurately reflect future trends or accurately estimate the future market for any of the Company’s product candidates. The Projections also reflect assumptions as to certain business decisions that are subject to change. Important factors that may affect actual results and result in the Projections not being achieved include, but are not limited to: (i) the success of clinical trials (including the funding therefor, anticipated patient enrollment, clinical outcomes, timing or associated costs); (ii) the prevailing treatment algorithm, (iii) regulatory approvals and related timelines; (iv) market size and market acceptance of the Company’s products; (v) the Company’s research, pre-clinical and clinical development of potential products and product candidates for different indications; (vi) risks related to the Company’s efforts to scale up its global supply chains and impact on gross margins; (vii) the impact of competitive products and pricing; (viii) the effect of regulatory actions; (ix) the availability of partnering arrangements on favorable terms or at all; (x) the effect of global economic conditions; (xi) conditions in the financing markets and access to sufficient capital; (xii) changes in applicable laws, rules and regulations; (xiii) accuracy of certain accounting assumptions; (xiv) changes in actual or projected cash flows; (xv) changes in applicable laws, rules and regulations; and (xvi) other risk factors described in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2024 and subsequent Quarterly Reports filed on Form 10-Q and Current Reports on Form 8-K, as well as the section of this proxy statement titled “Cautionary Statement Regarding Forward-Looking Statements” in this proxy statement. In addition, the Projections may be affected by the Company’s ability to achieve strategic goals, objectives and targets over the applicable period. Further, the Projections cover multiple years and, by their nature, become subject to greater uncertainty with each successive year. Accordingly, there can be no assurance that the Projections will be realized, and actual results may vary materially from those shown.

Modeling and forecasting the future development and commercialization of drug candidates by a clinical-stage company is a highly speculative endeavor. In addition to the various limitations described above, there can be no assurance of the approval, or timing of approval, of any of the Company’s product candidates, and it is possible that other therapeutic scenarios will be preferable. There also can be no assurance that the Company will obtain the approvals necessary for the commercialization of its product candidates, or that the Company’s competitors will not commercialize products that are safer, more effective, or more successfully marketed and sold than any product that the Company may market or commercialize. Since the Projections cover a long period of time, the Projections by their nature are unlikely to anticipate each circumstance that will have an effect on the Company. The Projections were not prepared with a view toward complying with the United States generally accepted accounting principles (“GAAP”), the published guidelines of the SEC regarding projections or the guidelines established by the American Institute of Certified Public Accountants for preparation and presentation of prospective financial information. Neither the Company’s independent registered public accounting firm nor any other independent accountant, has audited, reviewed, compiled or performed any procedures with respect to the Projections or expressed any opinion or any form of assurance related thereto.

The Projections were not prepared with a view toward public disclosure. The inclusion of the Projections in this proxy statement should not be regarded as an indication that the Company or any of its affiliates, advisors, officers, directors or representatives considered or consider the Projections to be predictive of actual future events, and the Projections should not be relied upon as such or construed as financial guidance. Neither the Company nor any of its affiliates assumes any responsibility for the accuracy of the Projections. Neither the Company nor any of its affiliates, advisors, officers, directors or representatives can give any assurance that actual results will not differ from the Projections, and none of them undertakes any obligation to update or otherwise revise or reconcile the Projections to reflect circumstances existing after the date the Projections were generated or to reflect the occurrence of future events even in the event that any or all of the assumptions underlying the Projections are shown to be in error. Neither the Company nor any of its affiliates, advisors, officers, directors or representatives has made or makes any representation or warranty to any stockholder of the Company regarding the ultimate performance of the Company compared to the information contained in the Projections, the likelihood that the Projections will be achieved, the results of the Company’s clinical trials, the timing and approval of commercial launch of any of the Company’s products, the effectiveness or marketability

64

of the Company’s product candidates, or the overall future performance of the Company. The Projections were prepared based on the Company’s continued operation as a stand-alone company and do not take into account the Transactions, or the effect of any business or strategic decision or action that has been or will be taken as a result of the execution of the Merger Agreement. The Projections are subjective in many respects and, thus, are subject to interpretation.

Certain of the measures included in the Projections, including unlevered free cash flow, are financial measures that are not calculated in accordance with GAAP. Such non-GAAP financial measures should not be viewed as a substitute for GAAP financial measures, and may be different from non-GAAP financial measures used by other companies. Furthermore, there are limitations inherent in non-GAAP financial measures, because they exclude charges and credits that are required to be included in a GAAP presentation. Accordingly, non-GAAP financial measures should be considered together with, and not as an alternative to, financial measures prepared in accordance with GAAP. The SEC rules, which otherwise would require a reconciliation of a non-GAAP financial measure to a GAAP financial measure, do not apply to non-GAAP financial measures provided to a board of directors or financial advisors in connection with a proposed business combination transaction such as the proposed Merger. In addition, reconciliations of non-GAAP financial measures to a GAAP financial measure were not provided to or relied upon by the Board of Directors in connection with its evaluation of the Merger or Centerview in connection with its financial analysis and opinion. Accordingly, the Company has not provided a reconciliation of the financial measures included in the Projections to the relevant GAAP financial measures.

The summary of the information below is included solely to give Company stockholders access to the information that was made available to Centerview and the Board of Directors, as described above, and is not included in this proxy statement in order to influence any Company stockholder to make any investment decision with respect to the Merger. In light of the foregoing factors and uncertainties inherent in the Projections, Company stockholders are cautioned not to place undue, if any, reliance on the summary of the Projections set forth below.

At the direction of the Board of Directors, the Company’s management calculated unlevered free cash flow as set forth below, which calculation has been reviewed and approved by the Board of Directors for reliance upon and use by Centerview in connection with the rendering of its opinion to the Board of Directors and in performing the related financial analyses as described in the section of this proxy statement titled “The Merger—Opinion of Centerview Partners LLC.” For purposes of calculating the discounted cash flow, the Projections assumed (i) estimated federal net operating losses of $319 million as of June 30, 2025 and estimated future losses and (ii) the net impact of assumed equity raises of $80 million in the third and fourth quarters of fiscal year 2025 and $1,300,000,000 in fiscal years 2026 through 2030 including a 10% discount and a 5% spread.

65

On the same basis as the Projections, the Company’s management also estimated the probability of success for achieving the Milestone set forth in the CVR Agreement to be a 16% probability of achieving the Milestone in advance of the end date of the Milestone Period (as defined below). The Board of Directors directed Centerview to use such estimated probability of success in Centerview’s analyses of the Merger Consideration in connection with and for purposes of rendering its opinion to the Board of Directors and in performing the related financial analysis as described in the section of this proxy statement titled “The Merger—Opinion of Centerview Partners LLC.” There can be no assurance that the Milestone will be achieved or that any payment with respect to the Milestone will be made.

THE COMPANY DOES NOT INTEND TO UPDATE OR OTHERWISE REVISE OR RECONCILE THE PROJECTIONS TO REFLECT CIRCUMSTANCES EXISTING AFTER THE DATE THE PROJECTIONS WERE GENERATED OR TO REFLECT THE OCCURRENCE OF FUTURE EVENTS, EVEN IN THE EVENT THAT ANY OR ALL OF THE ASSUMPTIONS UNDERLYING THE PROJECTIONS ARE SHOWN TO BE IN ERROR.

Interests of Company Executive Officers and Directors in the Transactions

In considering the recommendation of the Board of Directors that Company stockholders vote in favor of the Transaction Proposal, the Company stockholders should be aware that executive officers and directors of the Company may have certain interests in the Merger that are different from, or in addition to, the interests of the Company’s stockholders generally. The members of the Board of Directors were aware of and considered these potential interests, among other matters, in reaching the determination to approve and adopt the Merger Agreement and other related agreements and recommend to Company stockholders that they vote in favor of the Transaction Proposal as more fully discussed in the section of this proxy statement titled “The Merger—Recommendation of the Board of Directors; Reasons for the Merger.”

The Company’s current executive officers and non-employee directors and their respective positions are as follows:

66

Treatment of Company Equity Awards

Treatment of Company Options

The Merger Agreement provides that, as of the Effective Time, by virtue of the Merger and without any further action on the part of any holder of any Company Options, Parent, Merger Sub, or the Company:

The following table sets forth, for each of the Company’s executive officers and non-employee directors, (i) the aggregate number of shares of Company common stock underlying vested Company Options held by such individual as of June 11, 2025, (ii) the aggregate number of shares of Company common stock underlying unvested Company Options held by such individual as of June 11, 2025 and (iii) the estimated value that the executive officers and non-employee directors will receive in respect of such Company Options in connection with the Merger. Company Options held by the Company’s executive officers and directors with an exercise price that is equal to or greater than $10.00 per share will be cancelled for no consideration and are therefore not included in the table below. The following table assumes that no Company Options will be exercised between June 11, 2025 and the closing of the Merger. For each individual, the estimated aggregate value set forth below equals the product of (a) the Closing Amount plus the maximum amount payable for one CVR (i.e., a maximum total amount of $10.00 per share), less the weighted average exercise price of such individual’s unvested and vested Company Options that have an exercise price that is less than $10.00 per share, multiplied by (b) the total number of shares of Company common stock subject to such Company Options. Any differences in the value totals shown below relative to the component amounts are due to rounding adjustments and use of the weighted average exercise price to calculate the estimated aggregate payouts.

67

Treatment of Company RSUs

The Merger Agreement provides that, as of the Effective Time, by virtue of the Merger and without any further action on the part of the holder of any Company RSUs, Parent, Merger Sub, or the Company:

The following table sets forth, for each of the Company’s executive officers and non-employee directors, (i) the aggregate number of share of Company common stock underlying Company RSUs held by such individual as of June 11, 2025, and (ii) the estimated value that the executive officers and non-employee directors will receive in respect of such Company RSUs in connection with the Merger. The estimated aggregate values set forth below are based on the Closing Amount plus the maximum amount payable for one CVR (i.e., a maximum total amount of $10.00 per share), multiplied by the total number of shares of Company common stock subject to each applicable Company RSU award.

68

Employment Agreements with Executive Officers

We have entered into employment agreements with each of our executive officers (each, an “Employment Agreement”) that provide for specified payments and benefits in connection with a termination of employment in certain circumstances. Each Employment Agreement provides for certain payments and benefits if the executive’s employment with the Company is terminated by the Company without “cause,” or by the executive officer for “good reason,” in each case, upon or within twelve (12) months following a “change in control” (as defined in the applicable Employment Agreement) (any such termination, a “CIC Termination”). The Merger will qualify as a change in control under the Employment Agreements.

Upon a CIC Termination, each executive officer is entitled to receive the following payments and benefits:

All of the severance payments and benefits payable pursuant to the Employment Agreements in the event of a CIC Termination in connection with the Merger are subject to, among other things, the executive officer’s timely execution and non-revocation of a general release of claims in favor of the Company and related parties. The Employment Agreements also provide that if payments and benefits payable to each executive officer in connection with a change in control would be subject to the excise tax on golden parachutes imposed under Section 4999 of the Code, then those payments or benefits will be reduced if such reduction would result in a higher net after-tax benefit to the executive officer.

The following table sets forth the potential amounts payable to the Company’s executive officers upon a CIC Termination under the Employment Agreements, other than the value of accelerated Company Options and Company RSUs, which are set forth above.

69

Section 280G Payments

In connection with the Merger, the Company may enter into gross-up agreements, on terms reasonably acceptable to Parent, with certain individuals, including the executive officers, who would otherwise be subject to an excise tax pursuant to the provisions of Sections 280G and 4999 of the Code, with the aggregate amount of all such tax gross-ups not to exceed $2,430,000. The tax gross-up payments, if any, would generally be paid to the relevant taxing authorities to place the executive officers in the same after-tax position as if the excise tax did not apply to them.

Potential Future Parent Arrangements

Certain of the Company’s executive officers may continue to provide employment or other services to Parent after the Effective Time and may enter into new agreements, arrangements or understandings with Parent to set forth the terms and compensation of such post-Effective Time service. As of the date of this proxy statement, no such agreements, arrangements or understandings with Parent exist.

Continuing Employee Benefits

The Merger Agreement provides that, for a period of one year following the Effective Time, Parent will provide, or cause to be provided, to each employee of the Company who is employed by the Company as of immediately prior to the Effective Time and who continues to be employed by the Surviving Corporation (or any affiliate thereof) during such one-year period (each, a “Continuing Employee”) (i) a base salary (or base wages, as the case may be) and a target annual cash incentive compensation opportunity that are, for each component, no less favorable than those provided to such Continuing Employee immediately prior to the Effective Time, and (ii) broad-based employee benefits (excluding equity and equity-based awards (including with respect to the Company ESPP), severance, defined benefit pension benefits, retiree medical benefits and nonqualified deferred compensation, retention, transaction and change in control plans, programs, perquisites and arrangements)) that are substantially comparable in the aggregate to those provided to such Continuing Employee immediately prior to the Effective Time. In addition, for a period of one year following the Effective Time, Parent will provide, or cause to be provided, to each Continuing Employee who suffers a termination of employment under circumstances that would have given the Continuing Employee a right to severance payments and benefits under certain agreements and arrangements in effect immediately prior to the Closing with severance payments and benefits no less favorable than those that would have been provided to such Continuing Employee under the applicable agreement or arrangement.

Indemnification and Insurance

Pursuant to the terms of the Merger Agreement, the Company’s executive officers and directors will be entitled to certain ongoing indemnification. See the section of this proxy statement titled “The Merger Agreement—Indemnification of Officers and Directors” beginning on page 103 for a description of such ongoing indemnification and coverage obligations.

Material U.S. Federal Income Tax Consequences of the Merger

This section describes the material U.S. federal income tax consequences of the Merger.

70

This section applies solely to persons that hold shares of Company common stock as capital assets for tax purposes. This section addresses only U.S. federal income taxation and does not discuss all of the tax consequences that may be relevant to a holder in light of such holder’s individual circumstances, including non-U.S., state or local tax consequences, estate and gift tax consequences, and tax consequences arising under the Medicare contribution tax on net investment income or the alternative minimum tax. This section does not address tax considerations applicable to holders subject to special rules, including:

This section is based on the Internal Revenue Code of 1986, as amended (the “Code”), its legislative history, existing and proposed regulations, published rulings and court decisions, all as of the date of this proxy statement. These laws are subject to change, possibly on a retroactive basis. Any such change could alter the tax consequences to the holders as described herein.

This discussion is intended to provide only a general summary of the material U.S. federal income tax consequences of the Merger to holders of shares of the Company’s common stock. It is not intended to be a complete analysis or description of all potential U.S. federal income tax consequences of the Merger. The U.S. federal income tax laws are complex and subject to varying interpretations. Accordingly, the Internal Revenue Service (the “IRS”) may not agree with the tax consequences described in this proxy statement.

If an entity or arrangement treated as a partnership for U.S. federal income tax purposes holds shares of Company common stock, the tax treatment of a partner in such partnership generally will depend on the status of the partner and activities of the partnership. Holders that are partners of a partnership holding shares of Company common stock should consult their own tax advisors.

We have not sought, and do not intend to seek, any ruling from the IRS with respect to the statements made and the conclusions reached in the following summary, and no assurance can be given that the IRS will agree with the views expressed herein, or that a court will not sustain any challenge by the IRS in the event of litigation.

71

HOLDERS ARE URGED TO CONSULT WITH THEIR OWN TAX ADVISORS AS TO THE TAX CONSEQUENCES OF THE MERGER IN THEIR PARTICULAR CIRCUMSTANCES, INCLUDING THE APPLICABILITY AND EFFECT OF U.S. FEDERAL (INCLUDING THE ALTERNATIVE MINIMUM TAX), STATE, LOCAL OR NON-U.S. AND OTHER TAX LAWS AND OF CHANGES IN THOSE LAWS.

For purposes of this discussion, the term “U.S. holder” means a beneficial owner of shares of Company common stock that is, for U.S. federal income tax purposes:

A “Non-U.S. holder” is a beneficial owner (other than a partnership) of shares of Company common stock that is not a U.S. holder.

U.S. Holders

Tax Consequences of the Merger

The receipt of cash and CVRs by a U.S. holder in exchange for shares of Company common stock will be a taxable transaction for U.S. federal income tax purposes.

The amount of gain or loss a U.S. holder recognizes, and the timing and potential character of a portion of such gain or loss, depends on the U.S. federal income tax treatment of the CVRs, with respect to which there is a significant amount of uncertainty. The installment method of reporting any gain attributable to receipt of a CVR generally will not be available with respect to the disposition of shares of Company common stock pursuant to the Merger because the shares of Company common stock are traded on an established securities market.

There is no legal authority directly addressing the U.S. federal income tax treatment of the receipt of the CVRs in connection with the Merger. The receipt of the CVRs as part of the Merger Consideration might be treated as a “closed transaction” or as an “open transaction” for U.S. federal income tax purposes.

Pursuant to U.S. Treasury Regulations dealing with contingent payment obligations analogous to the CVRs, if the fair market value of the CVRs is “reasonably ascertainable,” a U.S. holder should treat the transaction as a “closed transaction” and treat the fair market value of the CVRs as part of the consideration received in the Merger for purposes of determining gain or loss. On the other hand, if the fair market value of the CVRs cannot be reasonably ascertained, a U.S. holder should treat the transaction as an “open transaction” for purposes of determining gain or loss. These U.S. Treasury Regulations state that only in “rare and extraordinary” cases would the value of contingent payment obligations not be reasonably ascertainable. The following paragraphs discuss the U.S. federal income tax consequences of the receipt of cash and CVRs in exchange for shares of Company common stock in the event it is treated as an “open transaction” and, alternatively, in the event it is treated as a “closed transaction.” There is no authority directly addressing whether contingent payment rights with characteristics similar to the rights under a CVR should be treated as “open transactions” or “closed transactions,” and such question is inherently factual in nature. The CVRs also may be treated as debt instruments for U.S. federal income tax purposes. However, as such treatment is unlikely, the discussion below does not address the tax consequences of such a characterization.

72

It is possible that either Parent or the Company may be required to take a position for income tax, withholding, and/or information reporting purposes that the Merger, including the receipt of the CVRs as part of the Merger, is either a “closed transaction” or an “open transaction.” U.S. holders are urged to consult their tax advisors regarding the proper characterization, method of tax accounting and tax reporting with respect to receipt of a CVR under the “closed transaction” method or “open transaction” method, as applicable to their respective case.

Treatment as Open Transactions

If the transaction is treated as an “open transaction” for U.S. federal income tax purposes, the fair market value of the CVRs would not be treated as additional consideration received for the shares of Company common stock at the time the CVRs are received, and the U.S. holder would have no tax basis in the CVRs. As such, a U.S. holder would generally recognize capital gains upon consummation of the Merger if, and to the extent, the cash received exceeds such U.S. holder’s basis in the shares of Company common stock surrendered with respect thereto.

The U.S. holder would then take payments under the CVRs into account when made or deemed made in accordance with the U.S. holder’s regular method of accounting for U.S. federal income tax purposes. A portion of any payments made more than one year after the Merger would be treated as interest income under Section 483 of the Code (as discussed below under the section titled “—U.S. Holders—Imputed Interest”) and the balance, in general, as additional consideration for the disposition of the shares of Company common stock.

Payments of cash pursuant to the CVRs that are not treated as imputed interest will generally result in capital gain to the U.S. holder if, and to the extent, such amounts (plus the cash received) exceed the U.S. holder’s adjusted tax basis in the shares of Company common stock. A U.S. holder may recognize capital loss if the amounts received do not equal or exceed the U.S. holder’s adjusted basis in the shares of Company common stock, although it is possible that such holder may not be able to recognize such loss until the resolution of all contingencies under the CVRs or possibly until such holder’s abandonment of the holder’s CVRs. Capital gain or loss recognized in the transaction must be determined separately for each identifiable block of shares of Company common stock (i.e., shares of Company common stock acquired at the same cost in a single transaction). Any such capital gain or loss will be long-term if the shares of Company common stock were held for more than one year prior to such disposition. The deductibility of capital losses is subject to certain limitations.

Treatment as Closed Transaction

If the receipt of the CVRs is treated as, or determined to be, part of a “closed transaction” for U.S. federal income tax purposes, then a U.S. holder of shares of Company common stock generally would recognize capital gain or loss, taking into account the “reasonably ascertainable” fair market value of the CVR determined on the date of the consummation of the Merger, as applicable, as an additional amount realized. It is possible that the trading value of Company’s common stock would be considered along with other factors in determining whether the value of the CVR is reasonably ascertainable. A U.S. holder’s initial tax basis in a CVR received in the Merger would equal the fair market value of such CVR as determined for U.S. federal income tax purposes. The holding period for a CVR would begin on the day following the date of the Effective Time.

The character of any gain, income or loss recognized with respect to a payment on a CVR is uncertain. Such payments may be treated as payments with respect to a sale or exchange of a capital asset or as giving rise to ordinary income, including in part as imputed interest, as described more fully below. Parent intends to treat any payment received by a U.S. holder in respect of a CVR (except to the extent any portion of such payment is required to be treated as imputed interest, as discussed below under the section titled “—U.S. Holders—Imputed Interest”) as an amount realized on the disposition of the applicable CVR by the U.S. holder. Under this method of reporting, a U.S. holder should recognize gain equal to the difference between such payment (less any portion

73

of such payment required to be treated as imputed interest, as described above) and the U.S. holder’s adjusted tax basis in the applicable CVR and, if the CVR expires without the Milestone being achieved, loss equal to the U.S. holder’s adjusted tax basis in the applicable CVR. A U.S. holder’s adjusted basis in a CVR generally will equal the CVR’s fair market value when the CVR was received pursuant to the Merger. The gain or loss will be long-term capital gain or loss if the U.S. holder has held the applicable CVR (or possibly the share of Company common stock in respect of which such CVR was received) for more than one year at the time of such payment or expiry. The deductibility of capital losses is subject to limitations.

Imputed Interest

Under either the “closed transaction” or “open transaction” treatment, if any payment with respect to a CVR is made more than one year after the Effective Time, a portion of any such payments made more than six (6) months after the Effective Date may be treated as imputed interest that is ordinary income to a U.S. holder under Section 483 of the Code. The portion of any payment made with respect to a CVR treated as imputed interest will be determined at the time such payment is made and generally should equal the excess of (1) the amount of the CVR payment over (2) the present value of such amount as of the Effective Time, calculated using the applicable federal rate as the discount rate. The applicable federal rate is published monthly by the IRS. A U.S. holder must include in its taxable income interest imputed pursuant to Section 483 of the Code using such holder’s regular method of accounting for U.S. federal income tax purposes.

Non-U.S. Holders

Tax Consequences of the Merger

Any gain recognized on the receipt of the Merger Consideration pursuant to the Merger by a Non-U.S. holder generally will not be subject to U.S. federal income tax unless:

Gain described in the first bullet point above generally will be subject to U.S. federal income tax on a net income basis at the regular rates. A Non-U.S. holder that is a corporation also may be subject to a branch profits tax at a rate of 30% (or such lower rate specified by an applicable income tax treaty) on such effectively connected gain, as adjusted for certain items.

Gain described in the second bullet point above will be subject to U.S. federal income tax at a rate of 30% (or such lower rate specified by an applicable income tax treaty), which may be offset by U.S. source capital losses of the Non-U.S. holder (even though the individual is not considered a resident of the United States), provided the Non-U.S. holder has timely filed U.S. federal income tax returns with respect to such losses.

With respect to the third bullet point above, the Company does not expect that it is, or anticipate becoming, a USRPHC. Even if the Company were a USRPHC, gain arising from the sale or other taxable disposition by a Non-U.S. holder of shares of Company common stock will not be subject to U.S. federal income tax if such stock is “regularly traded,” as defined by applicable U.S. Treasury Regulations, on an established securities market, and such Non-U.S. holder owned, actually and constructively, 5% or less of such stock throughout the shorter of the five-year period ending on the date of the sale or other taxable disposition or the Non-U.S. holder’s holding period, or if another exception from these rules under the Code applies.

74

Generally, any portion of a payment made to a Non-U.S. holder with respect to a CVR that is treated as imputed interest (as discussed above under the section titled “—U.S. Holders—Imputed Interest”) may be subject to withholding at a rate of 30%, unless such Non-U.S. holder establishes its entitlement to exemption from or a reduced rate of withholding under an applicable income tax treaty by providing the appropriate documentation (generally, IRS Form W-8BEN or W-8BEN-E) to the applicable withholding agents.

Non-U.S. holders should consult their tax advisors regarding potentially applicable income tax treaties that may provide for different rules.

Information Reporting, Backup Withholding and FATCA Withholding

U.S. Holders

A U.S. holder may be subject to information reporting and backup withholding when such holder receives proceeds from the sale or other taxable disposition of the shares of Company common stock in the Merger. Certain U.S. holders are exempt from backup withholding, including corporations and certain tax-exempt organizations. A U.S. holder will be subject to backup withholding if such holder is not otherwise exempt and:

Backup withholding is not an additional tax. Any amounts withheld under the backup withholding rules may be allowed as a refund or a credit against a U.S. holder’s U.S. federal income tax liability, provided the required information is timely furnished to the IRS.

U.S. holders should consult their tax advisors regarding their qualification for an exemption from backup withholding and the procedures for obtaining such an exemption.

Non-U.S. Holders

Proceeds from the sale or other taxable disposition of the shares of Company common stock in the Merger within the United States or conducted through certain U.S.-related brokers generally will not be subject to backup withholding or information reporting, if the applicable withholding agent receives the certification described above and does not have actual knowledge or reason to know that such holder is a U.S. person, or the holder otherwise establishes an exemption. Proceeds from a sale or other taxable disposition of the shares of Company common stock in the Merger conducted through a non-U.S. office of a non-U.S. broker generally will not be subject to backup withholding or information reporting.

Copies of information returns that are filed with the IRS may also be made available under the provisions of an applicable treaty or agreement to the tax authorities of the country in which the Non-U.S. holder resides or is established.

Backup withholding is not an additional tax. Any amounts withheld under the backup withholding rules may be allowed as a refund or a credit against a Non-U.S. holder’s U.S. federal income tax liability, provided the required information is timely furnished to the IRS.

75

FATCA

Sections 1471 through 1474 of the Code (commonly referred to as “FATCA”) impose a U.S. federal withholding tax of 30% on certain payments made to a “foreign financial institution” (as specially defined under these rules) unless such institution enters into an agreement with the U.S. government to withhold on certain payments and to collect and provide to the U.S. tax authorities substantial information regarding certain U.S. account holders of such institution (which includes certain equity and debt holders of such institution, as well as certain account holders that are foreign entities with U.S. owners) or an exemption applies. FATCA also generally will impose a U.S. federal withholding tax of 30% on certain payments made to a non-financial foreign entity unless such entity provides the withholding agent a certification identifying certain direct and indirect U.S. owners of the entity or an exemption applies. An intergovernmental agreement between the United States and an applicable foreign country may modify these requirements. Under certain circumstances, a Non-U.S. holder might be eligible for refunds or credits of such taxes.

Under currently proposed Treasury Regulations, FATCA withholding would no longer apply to payments of gross proceeds from the sale or other disposition of property of a type that can generate U.S. source interest or dividends, including the Company common stock. Taxpayers generally may rely on these proposed Treasury Regulations until final Treasury Regulations are issued.

Non-U.S. holders should consult their tax advisors regarding the possible implications of the FATCA rules on their receipt of, and payments with respect to, the CVRs.

Regulatory Approvals

Under the terms of the Merger Agreement, the Company and Parent will use reasonable best efforts to obtain antitrust approvals, subject to certain limitations. The Merger cannot be completed until the waiting period (and any extension thereof) under the HSR Act applicable to the Merger or the Transactions has expired or been terminated. In addition to antitrust approval in the United States, the completion of the Merger may be subject to the receipt of certain regulatory approvals of other jurisdictions if in order to complete the Merger such approvals are required, or become required as a result of any regulatory authority asserting jurisdiction over the transaction.

On June 16, 2025, the Company and Parent filed notification of the proposed Merger with the Federal Trade Commission (the “FTC”) and the Department of Justice (the “DOJ”) under the HSR Act. The applicable waiting period under the HSR Act expired at 11:59 p.m., Eastern Time, on July 16, 2025.

Completion of the Merger may also be subject to the receipt of certain antitrust or competition approvals of other jurisdictions if in order to complete the Merger such approvals are required, or become required as a result of any regulatory authority asserting jurisdiction over the Merger.

At any time before or after consummation of the Merger, the DOJ or the FTC (notwithstanding the termination of the waiting period under the HSR Act) could take such action under antitrust laws as they deem necessary or desirable in the public interest, including seeking to enjoin the completion of the Merger and seeking divestiture of substantial assets of the Company or Parent. At any time before or after the completion of the Merger (and notwithstanding the termination of the waiting period under the HSR Act), any state or non-U.S. governmental entity could take such action under antitrust laws as it deems necessary or desirable in the public interest. Such action could include seeking to enjoin the completion of the Merger and seeking divestiture of substantial assets of the Company or Parent. Private parties may also seek to take legal action under antitrust laws under certain circumstances.

There can be no assurance that all of the regulatory approvals described above, or any other regulatory approvals that might be required to consummate the Merger, will be sought or obtained and, if obtained, there can be no assurance as to the timing of any approvals, ability to obtain the approvals on satisfactory terms or the absence of any litigation challenging such approvals. There can also be no assurance that the DOJ, the FTC or

76

any other governmental entity or any private party will not attempt to challenge the Merger on antitrust grounds, and, if such a challenge is made, there can be no assurance as to its result. For a description of the parties’ obligations with respect to regulatory approvals related to the Merger, see the section titled “The Merger Agreement—Filings; Other Actions; Notification” beginning on page 95 of this proxy statement.

Legal Proceedings

As of the date of this proxy statement, there are no legal proceedings pending challenging the Merger.

Delisting and Deregistration of the Company Common Stock

Upon completion of the Merger, the shares of Company common stock currently listed on the Nasdaq will cease to be listed on the Nasdaq and will subsequently be deregistered under the Exchange Act. The Company will also no longer file periodic reports with the SEC on account of the Company common stock.

Appraisal Rights

If the Merger is consummated, holders of record or beneficial owners of shares of Company common stock who (i) do not vote in favor of the Transaction Proposal, (ii) continuously hold (in the case of holders of record) or continuously own (in the case of beneficial owners) their applicable shares of Company common stock through the Effective Time, (iii) properly demand appraisal of their applicable shares, (iv) meet certain statutory requirements described in this proxy statement and (v) do not withdraw their demands or otherwise lose their rights to appraisal will be entitled to seek appraisal of their shares in connection with the Merger under Section 262 if certain conditions set forth in Section 262(g) of the DGCL are satisfied. The requirements under Section 262 for perfecting and exercising appraisal rights are described in further detail in the section of this proxy statement titled “Appraisal Rights,” which description is qualified in its entirety by Section 262, which is the relevant section of the DGCL regarding appraisal rights, a copy of which may be accessed without subscription or cost at the following publicly available website: https://delcode.delaware.gov/title8/c001/sc09/index.html#262.

Holders of record and beneficial owners of shares of Company common stock who are entitled to have their shares appraised by the Delaware Court of Chancery may receive payment in cash of the “fair value” of their shares of Company common stock, exclusive of any element of value arising from the accomplishment or expectation of the Merger, together with (unless the Delaware Court of Chancery in its discretion determines otherwise for good cause shown) interest on the amount determined by the Delaware Court of Chancery to be fair value from the Effective Time through the date of payment of the judgment at a rate of 5% over the Federal Reserve discount rate (including any surcharge) as established from time to time during the period between the Effective Time and the date of payment of the judgment, compounded quarterly (except that, if at any time before the entry of judgment in the proceeding, the Surviving Corporation makes a voluntary cash payment to persons entitled to appraisal, interest will accrue thereafter only upon the sum of (i) the difference, if any, between the amount so paid and the fair value of the shares as determined by the Delaware Court of Chancery and (ii) interest theretofore accrued, unless paid at that time). The Surviving Corporation is under no obligation to make such voluntary cash payment prior to such entry of judgment. Due to the complexity of the appraisal process, any persons who wish to seek appraisal of their shares are encouraged to seek the advice of legal counsel with respect to the exercise of appraisal rights. Persons considering seeking appraisal should be aware that the fair value of their shares as determined pursuant to Section 262 could be more than, the same as or less than the value of the consideration that they would receive pursuant to the Merger Agreement if they did not seek appraisal of their shares. For more information, see the section titled “Appraisal Rights—Determination of Fair Value” beginning on page 113 of this proxy statement.

To exercise appraisal rights, a holder of record or a beneficial owner of shares of Company common stock must (i) submit a written demand for appraisal of such holder’s shares or such beneficial owner’s shares of

77

Company common stock to Company before the vote is taken on the Transaction Proposal, (ii) not vote, in person or by proxy, in favor of the Transaction Proposal (whether by voting against the Transaction Proposal, abstaining or otherwise not voting with respect to the Transaction Proposal), (iii) continuously hold (in the case of holders of record) or continuously own (in the case of beneficial owners) the subject shares of Company common stock through the Effective Time and (iv) strictly comply with all other procedures for exercising appraisal rights under the DGCL. If you are a beneficial owner of shares of Company common stock and you wish to exercise appraisal rights in such capacity, in addition to the foregoing requirements, your demand for appraisal must also (i) reasonably identify the holder of record of the shares of Company common stock for which the demand is made, (ii) be accompanied by documentary evidence of your beneficial ownership of stock and a statement that such documentary evidence is a true and correct copy of what it purports to be and (iii) provide an address at which you consent to receive notices given by the Surviving Corporation hereunder and to be set forth on the verified list required by Section 262(f) of the DGCL. The failure to follow exactly the procedures specified under the DGCL may result in the loss of appraisal rights. The requirements under Section 262 for perfecting and exercising appraisal rights are described in further detail in the section of this proxy statement titled “Appraisal Rights,” which description is qualified in its entirety by Section 262, which is the relevant section of the DGCL regarding appraisal rights, a copy of which may be accessed without subscription or cost at the following publicly available website: https://delcode.delaware.gov/title8/c001/sc09/index.html#262.

78

VOTE ON ADJOURNMENT (PROPOSAL NO. 2)

The Company is requesting stockholders to approve a proposal to, as permitted under the terms of the Merger Agreement, adjourn the Special Meeting, from time to time, if necessary or appropriate, to solicit additional votes for the approval of the proposal to adopt the Merger Agreement if there are insufficient votes at the time of the Special Meeting to adopt the Merger Agreement.

If the Adjournment Proposal is approved, the Special Meeting may be adjourned by the Company as permitted under the terms of the Merger Agreement to any date, except that the Company will not adjourn the meeting for more than ten (10) business days past the originally scheduled date without Parent’s prior consent. Under the terms of the Merger Agreement, if this Adjournment Proposal is approved, the Company will reconvene the Special Meeting on the earliest practicable date on which the Board of Directors reasonably expects to have sufficient affirmative votes to adopt the Transaction Proposal. If the Special Meeting is adjourned for the purpose of soliciting additional votes, stockholders who have already submitted their proxies will be able to revoke them at any time prior to their use. If you return a proxy and do not indicate how you wish to vote on any proposal, your shares will be voted in favor of such proposal. The Company does not intend to call a vote on this proposal if the Transaction Proposal has been approved at a Special Meeting.

The Special Meeting may be adjourned to another place, date or time with the affirmative vote of the holders of a majority of the shares of Company common stock properly cast for and against the Adjournment Proposal at the Special Meeting and entitled to vote on the Adjournment Proposal. Approval of the Adjournment Proposal in a situation in which a quorum is not present or represented at the Special Meeting requires the affirmative vote of the holders of a majority of the shares of Company common stock present at the Special Meeting and entitled to vote on the Adjournment Proposal.

THE BOARD OF DIRECTORS UNANIMOUSLY RECOMMENDS THAT STOCKHOLDERS VOTE “FOR” THE ADJOURNMENT PROPOSAL.

79

THE MERGER AGREEMENT

Explanatory Note Regarding the Merger Agreement

This section describes the material terms of the Merger Agreement. The description of the Merger Agreement in this section and elsewhere in this proxy statement is qualified in its entirety by reference to the complete text of the Merger Agreement, a copy of which is attached as Annex A and is incorporated by reference into this proxy statement. This summary does not purport to be complete and may not contain all of the information about the Merger Agreement that is important to you. We encourage you to read the Merger Agreement carefully and in its entirety. Capitalized terms used but not defined in this proxy statement have the meanings ascribed to them in the Merger Agreement.

The Merger Agreement and this summary of its terms are included to provide you with information regarding its terms. It is not intended to provide any other factual information about the Company, Parent, Merger Sub or their respective subsidiaries or affiliates. The representations, warranties and covenants made in the Merger Agreement by the Company, Parent and Merger Sub were made solely to the parties to, and solely for the purposes of, the Merger Agreement and as of specific dates and were qualified and subject to important limitations agreed to by the Company, Parent and Merger Sub in connection with negotiating the terms of the Merger Agreement. In particular, in your review of the representations and warranties contained in the Merger Agreement and described in this summary, it is important to bear in mind that the representations and warranties were negotiated with the principal purposes of establishing the circumstances in which a party to the Merger Agreement may have the right not to consummate the Merger if the representations and warranties of the other party prove to be untrue due to a change in circumstance or otherwise, and allocating risk between the parties to the Merger Agreement, rather than establishing matters as facts. The representations and warranties may also be subject to a contractual standard of materiality different from those generally applicable to stockholders and reports and documents filed with the SEC and in some cases were qualified by the matters contained in the Disclosure Schedule, which disclosures were not reflected in the Merger Agreement. Moreover, information concerning the subject matter of the representations and warranties may have changed since the date of the Merger Agreement. Accordingly, the representations, warranties, covenants and other agreements in the Merger Agreement should not be read alone, and you should read the information provided elsewhere in this proxy statement and in our filings with the SEC regarding the Company and our business. See the section of this proxy statement titled “Where You Can Find Additional Information.” In addition, you should not rely on the representations, warranties and covenants or any description thereof as characterizations of the actual state of facts of the Company, Parent, Merger Sub or any of their respective subsidiaries or affiliates.

Effects of the Merger

The Merger Agreement provides that upon the terms and subject to the conditions of the Merger Agreement at the Effective Time, Merger Sub will be merged with and into the Company and the separate corporate existence of Merger Sub will cease. At the Effective Time, the Company will continue as the Surviving Corporation in the Merger and a wholly owned subsidiary of Parent.

In addition, after the Effective Time, Company common stock will be delisted from Nasdaq and will be deregistered under the Exchange Act.

Closing and Effective Time of the Merger

Unless otherwise mutually agreed in writing by the parties to the Merger Agreement, the closing of the Merger (the “Closing”) will take place at 8:00 a.m. Eastern Time on the second business day following the day on which all of the conditions to the Closing (as described under the section titled “The Merger Agreement—Conditions to the Merger” beginning on page 97 of this proxy statement) are satisfied or waived in accordance with the Merger Agreement (other than conditions that by their nature are to be satisfied at or immediately prior

80

to the Closing, but subject to the satisfaction or waiver of those conditions at or prior to the Closing). The date upon which the Closing actually occurs is referred to herein as the “Closing Date.” On the Closing Date, the parties will file a execute and deliver a certificate of merger with the Secretary of State for the State of Delaware for filing as provided under the DGCL. The Merger will become effective upon the filing and acceptance for record of the certificate of merger, or at such later time as may be agreed by the parties in writing and specified in the certificate of merger.

Directors and Officers; Certificate of Incorporation; Bylaws

At the Effective Time, the directors and officers of Merger Sub immediately prior to the Effective Time will be the directors and officers of the Surviving Corporation, respectively, in each case until their respective successors have been duly elected or appointed and qualified, or until their earlier death, disqualification, resignation or removal in accordance with the certificate of incorporation and bylaws of the Surviving Corporation. At the Effective Time, (i) the certificate of incorporation of the Company will be amended and restated in its entirety to read as set forth in Exhibit B to the Merger Agreement and (ii) the bylaws of the Company will be amended and restated in their entirety to be in the form of the bylaws of Merger Sub, as in effect immediately prior to the Effective Time (except that the name of the Surviving Corporation will be “Vigil Neuroscience, Inc.”).

Treatment of Company common stock and Company preferred stock

At the Effective Time, by virtue of the Merger and without any further action on the part of Parent, Merger Sub, the Company or any stockholder of the Company:

81

Treatment of Company Equity Awards and the Company ESPP

Treatment of Company Options

As of the Effective Time, by virtue of the Merger and without any further action on the part of the holder of any Company Options, Parent, Merger Sub, or the Company, each outstanding Company Option will be treated as follows:

Treatment of Company RSUs

As of the Effective Time, by virtue of the Merger and without any further action on the part of the holder of any Company RSUs, Parent, Merger Sub, or the Company, each outstanding Company RSU will be treated as follows:

Treatment of the Company ESPP

As soon as reasonably practicable following the date of the Merger Agreement, and in any event prior to the Effective Time, the Company will take all necessary actions, including obtaining any necessary determinations or

82

resolutions of the Board of Directors (or a committee thereof), as may be necessary or required under the Company ESPP and applicable legal requirements, to (i) ensure that no offering period under the Company ESPP will be authorized or commenced on or after the date of the Merger Agreement; and (ii) ensure that no further rights are granted under the Company ESPP after the Effective Time. Immediately prior to and effective as of the Effective Time (but subject to the consummation of the Transactions), the Company will terminate the Company ESPP.

Treatment of Company Warrants

Each Company Warrant that is outstanding immediately prior to the Effective Time will be cancelled as of the Effective Time in exchange for the right to receive (i) cash in an amount equal to the product of (a) the Warrant Shares and (b) the Closing Amount, and (ii) a number of CVRs equal to the total number of Warrant Shares as of immediately prior to the Effective Time.

Surrender and Payment Procedures

Prior to the Effective Time, Parent will designate Computershare Trust Company, N.A. (or another nationally recognized bank or trust company agreed to between Parent and Company) to act as paying agent (the “Paying Agent”) for the holders of shares of Company common stock in connection with the Merger and to receive the funds to which holders of shares of Company common stock will become entitled in accordance with the Merger Agreement. At or promptly following the Effective Time, Parent will deposit or cause to be deposited with the Paying Agent cash sufficient to make payment of the aggregate Closing Amount.

Promptly after the Effective Time (but in no event later than three (3) business days thereafter), the Surviving Corporation will cause to be mailed to each holder of record of shares of Company common stock entitled to receive Merger Consideration (i) a letter of transmittal and (ii) instructions describing how such holder may surrender his, her or its Certificates or non-certificated shares represented by book-entry (“Book-Entry Share”) in exchange for payment of the Merger Consideration.

Upon surrender of the certificates evidencing such shares of Company common stock (the “Certificate”) (or effective affidavits of loss in lieu thereof) or Book-Entry Shares to the Paying Agent in accordance with the terms of the letter of transmittal, duly executed and properly completed and such other documents as may be reasonably requested by the Paying Agent, the holder of such Certificates or Book-Entry Shares will be entitled to receive in exchange therefor the Merger Consideration for each share of Company common stock formerly evidenced by such Certificates or Book-Entry Shares, and such the Certificates and Book-Entry Shares will forthwith be cancelled.

Any portion of the funds (including any interest received with respect thereto) that remains not disbursed or pending disbursement as of the date that is twelve (12) months after the Effective Time may be delivered to the Company upon demand, and any such holder of shares of the Company common stock who has not exchanged shares of the Company common stock for the Merger Consideration will thereafter look only to the Surviving Corporation for payment of the Merger Consideration (subject to applicable abandoned property, escheat and other similar law). No interest will be paid or accrued on the Merger Consideration payable upon due surrender of the Certificates or Book-Entry Shares.

Contingent Value Rights Agreement

At or prior to the Effective Time, Parent will enter into a Contingent Value Rights Agreement with the a rights agent (the “Rights Agent”), in substantially the form attached as an exhibit to the Merger Agreement (the “CVR Agreement”). Pursuant to the Merger Agreement and the CVR Agreement, each CVR represents the contractual right of Holders (as defined in the CVR Agreement) to receive a contingent cash payment of $2.00 in cash, without interest, payable to the Rights Agent for the benefit of the holders of CVRs, if the First Commercial Sale (as defined in the CVR Agreement) of the Company’s clinical candidate VG-3927 (the “Milestone”) occurs between the Effective Time and December 31, 2035 (the “Milestone Period”).

83

If the Milestone occurs at any time prior to the expiration of the Milestone Period, then, at least ten (10) business days prior to the Milestone Payment Date (as defined in the CVR Agreement), Parent will deliver or cause to be delivered to the Rights Agent a written notice (the “Milestone Achievement Notice”) certifying the date of the satisfaction of the Milestone and that each Holder is entitled to receive the Milestone Payment Amount (as defined in the CVR Agreement) applicable to such Holder. The Rights Agent will promptly, and in any event within five (5) Business Days of receipt of the Milestone Achievement Notice and any letter of instruction reasonably required by the Rights Agent, send each Holder at its registered address a copy of such Milestone Achievement Notice and pay the Milestone Payment Amount, subject to any amounts deducted or withheld pursuant to Section 2.4(d) of the CVR Agreement, to each Holder that is not an Equity Award Holder. If the Milestone is achieved prior to the end of the Milestone Period, the Milestone Payment (as defined in the CVR Agreement) shall be paid to the Holders on a date selected by Parent, but in no event later than thirty (30) business days after the date on which the Milestone was achieved.

Any portion of the aggregate Milestone Payment Amounts that remain undistributed to the Holders on the date that is twelve (12) months after the date of the Milestone Achievement Notice shall be delivered by the Rights Agent to Parent and any Holder shall thereafter look only to Parent for payment of such Holder’s applicable Milestone Payment Amount, without interest, but such Holder shall have no greater rights against Parent than those accorded to general unsecured creditors of Parent under applicable Legal Requirements.

The right to the contingent consideration as evidenced by the CVR Agreement is a contractual right only. The CVRs will not be transferable, except in the limited circumstances specified in the CVR Agreement, will not be evidenced by certificate or other instrument and will not be registered for trading. The CVRs will not have any voting or dividend rights and will not represent any equity or ownership interest in Parent or the Company.

Under the CVR Agreement, during the Milestone Period, Parent is obligated to use Diligent Efforts (as defined in the CVR Agreement) to achieve the Milestone prior to the end of the Milestone. However, there can be no assurance that such First Commercial Sale will occur by December 31, 2035 and that the $2.00 CVR payment (or the Underwater Option CVR Payment (as defined in the CVR Agreement)) will be paid to CVR holders.

The CVR Agreement will terminate and be of no force or effect upon the earlier to occur (i) the payment by Parent of the Milestone Payment Amount required to be paid under the terms of the CVR Agreement and (ii) the expiration of the Milestone Period. For the avoidance of doubt (A) the termination of the CVR Agreement will not affect or limit the right to receive the Milestone Payment under Section 2.4 of the CVR Agreement to the extent earned but not paid prior to termination of the CVR Agreement and (B) the right of any Holder to receive the Milestone Payment, and all covenants and obligations of Parent and its affiliates with respect to the Milestone Payment, shall be irrevocably terminated and extinguished if the Milestone is not achieved prior to the expiration of the Milestone Period.

The CVR Agreement is subject to changes reasonably requested by the Rights Agent to which Parent and the Company consent in writing. Parent and the Company will cooperate, including by making changes to the form of CVR Agreement, as necessary and appropriate to ensure that the CVRs are not subject to registration under the Securities Act of 1933, as amended (the “Securities Act”), the Exchange Act or any applicable state securities or “blue sky” laws.

Representations and Warranties

Representations and Warranties of the Company

We have made customary representations and warranties in the Merger Agreement that are subject to exceptions and disclosures set forth in the Disclosure Schedule and disclosures contained certain documents filed

84

with or furnished to the SEC by the Company prior to the date of the Merger Agreement. These representations and warranties relate to, among other things:

85

Material Adverse Effect

Some of our representations and warranties are qualified to be, among other things, “materiality” or “Material Adverse Effect,” which means any event, change, occurrence, circumstance, development or effect (each, a “Change”) that, individually or in the aggregate, either (i) has had or would reasonably be expected to have a material adverse effect on the business, assets, condition (financial or otherwise) or results of operations of the Company and its subsidiaries, taken as a whole, or (ii) would prevent or materially delay the consummation by the Company of the Merger and the other transactions contemplated within the Merger Agreement. However, none of the following will be taken into account in determining whether is, or would reasonably likely to be, a Material Adverse Effect:

86

Except that, with respect to bullets 3, 4, 5, 9 and 11 above, any Change may be taken into account in determining whether there has been, or would be reasonably expected to be, a Material Adverse Effect to the extent such Change disproportionately affects the Company and its Subsidiaries relative to other participants in the industries in which they operate.

Representations and Warranties of Parent and Merger Sub

The Merger Agreement also contains customary representations and warranties made by Parent and Merger Sub that are subject, in some cases, to specified exceptions and qualifications contained in the Merger Agreement. The representations and warranties of Parent and Merger Sub relate to, among other things:

Conduct of Our Business Pending the Merger

Under the Merger Agreement, the Company has agreed that from the date of the Merger Agreement until the earlier of the Effective Time and the termination of the Merger Agreement (the “Pre-Closing Period”), except

87

(i) as required or otherwise expressly contemplated by the Merger Agreement or as required by applicable legal requirements, (ii) with the written consent of Parent which will not unreasonably withheld, conditioned or delayed or (iii) as set forth in the Disclosure Schedule, the Company will and will cause its subsidiaries to:

In addition, during the Pre-Closing Period, except as (i) as required or otherwise expressly contemplated by the Merger Agreement or as required by applicable legal requirements, (ii) with the written consent of Parent which will not unreasonably withheld, conditioned or delayed or (iii) as set forth in the Disclosure Schedule, the Company will not, and will cause its subsidiaries not to: