Pricing Information Provided Orally by Underwriters The number of Underwritten Shares purchased by the Underwriters is 17,150,000. The number of Option Shares is 2,572,500. The public offering price per share is $17.50. Written Testing-the-Waters Communications None. Form of Lock-Up Agreement January , 2024 XXXXXX XXXXXXX & CO. LLC X.X. XXXXXX SECURITIES LLC XXXXXXXXX LLC As Representatives of the several Underwriters listed in Schedule 1 to the Underwriting Agreement referred to below c/x Xxxxxx Xxxxxxx & Co. LLC 0000 Xxxxxxxx New York, New York 10036 c/o X.X. Xxxxxx Securities LLC 000 Xxxxxxx Xxxxxx New York, New York 10179 c/x Xxxxxxxxx LLC 000 Xxxxxxx Xxxxxx New York, New York 10022 Ladies and Gentlemen: The undersigned understands that you, as representatives (the “Representatives”) of the several Underwriters, propose to enter into an underwriting agreement (the “Underwriting Agreement”) with Dyne Therapeutics, Inc., a Delaware corporation (the “Company”), providing for the public offering (the “Public Offering”) by the several Underwriters named in Schedule 1 to the Underwriting Agreement (the “Underwriters”), of common stock, par value $0.0001 per share (the “Common Stock”), of the Company (the “Securities”). Capitalized terms used herein and not otherwise defined shall have the meanings set forth in the Underwriting Agreement. In consideration of the Underwriters’ agreement to purchase and make the Public Offering of the Securities, and for other good and valuable consideration receipt of which is hereby acknowledged, the undersigned xxxxxx agrees that, without the prior written consent of Xxxxxx Xxxxxxx & Co. LLC, X.X. Xxxxxx Securities LLC and Xxxxxxxxx LLC on behalf of the Underwriters, the undersigned will not, and will not cause any direct or indirect affiliate to, during the period beginning on the date of this letter agreement (this “Letter Agreement”) and ending at the close of business 60 days after the date of the final prospectus supplement relating to the Public Offering (the “Prospectus”) (such period, the “Restricted Period”), (1) offer, pledge, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to purchase, lend, or otherwise transfer or dispose of, directly or indirectly, any shares of Common Stock or any securities convertible into or exercisable or exchangeable for Common Stock (including without limitation, Common Stock or such other securities which may be deemed to be beneficially owned by the undersigned in accordance with the rules and regulations of the Securities and Exchange Commission and securities which may be issued upon exercise of a stock option or warrant) (collectively with the Common Stock, the “Lock-Up Securities”), (2) enter into any hedging, swap or other agreement or transaction that transfers, in whole or in part, any of the economic consequences of ownership of the Lock-Up Securities, whether any such transaction described in clause (1) or (2) above is to be settled by delivery of Lock-Up Securities, in cash or otherwise, (3) make any demand for or exercise any right with respect to the registration of any Lock-Up Securities, or (4) publicly disclose the intention to do any of the foregoing. Notwithstanding the foregoing, the undersigned may:
(a) transfer or dispose of the undersigned’s Lock-Up Securities:
(i) as a bona fide gift or gifts, or for bona fide estate planning purposes,
(ii) by will, other testamentary document or intestacy,
(iii) to any trust for the direct or indirect benefit of the undersigned or the immediate family of the undersigned, or if the undersigned is a trust, to a trustor or beneficiary of the trust or to the estate of a beneficiary of such trust (for purposes of this Letter Agreement, “immediate family” shall mean any relationship by blood, current or former marriage, domestic partnership or adoption, not more remote than first cousin),
(iv) to a corporation, partnership, limited liability company, trust or other entity of which the undersigned and/or one or more members of the immediate family of the undersigned are, directly or indirectly, the legal and beneficial owner of all of the outstanding equity securities or similar interests,
(v) to a nominee or custodian of a person or entity to whom a disposition or transfer would be permissible under clauses (i) through (iv) above,
(vi) if the undersigned is a corporation, partnership, limited liability company, trust or other business entity, (A) to another corporation, partnership, limited liability company, trust or other business entity that is an affiliate (as defined in Rule 405 promulgated under the Securities Act of 1933, as amended) of the undersigned, or to any investment fund or other entity controlling, controlled by, managing or managed by or under common control with the undersigned or affiliates of the undersigned (including, for the avoidance of doubt, where the undersigned is a partnership, to its general partner or a successor partnership or fund, or any other funds managed by such partnership), or (B) as part of a distribution or other transfer to general or limited partners, members or shareholders of, or other holders of equity in, the undersigned,
(vii) by operation of law, such as pursuant to a qualified domestic order, divorce settlement, divorce decree, separation agreement or court order,
(viii) to the Company from an employee or other service provider of the Company upon death, disability or termination of employment or service relationship, in each case, of such employee or service provider,
(ix) as part of a sale of the undersigned’s Lock-Up Securities acquired in the Public Offering (other than, in the case of an officer or director of the Company, any Securities such officer or director may purchase in the Public Offering) or in open market transactions after the closing date for the Public Offering,
(x) to the Company in connection with the vesting, settlement, or exercise of restricted stock units, options, warrants or other rights to purchase shares of Common Stock (including, in each case, by way of “net” or “cashless” exercise), including for the payment of exercise price and tax and remittance payments due as a result of the vesting, settlement, or exercise of such restricted stock units, options, warrants or rights, provided that any such shares of Common Stock received upon such exercise, vesting or settlement shall be subject to the terms of this Letter Agreement, and provided further that any such restricted stock units, options, warrants or rights are held by the undersigned pursuant to an agreement or equity award granted under a stock incentive plan or other equity award plan or other arrangement, each such agreement, plan or arrangement which is described in the Registration Statement, the Pricing Disclosure Package and the Prospectus,
(xi) pursuant to a bona fide third-party tender offer, merger, consolidation or other similar transaction that is approved by the Board of Directors of the Company and made to all holders of the Company’s capital stock involving a Change of Control (as defined below) of the Company (for purposes hereof, “Change of Control” shall mean the transfer (whether by tender offer, merger, consolidation or other similar transaction), in one transaction or a series of related transactions, to a person or group of affiliated persons, of shares of capital stock if, after such transfer, such person or group of affiliated persons would hold at least a majority of the outstanding voting securities of the Company (or the surviving entity)); provided that in the event that such tender offer, merger, consolidation or other similar transaction is not completed, the undersigned’s Lock-Up Securities shall remain subject to the provisions of this Letter Agreement, or