Sec Form 4 Filing - VV Manager II, LLC @ Dyne Therapeutics, Inc. - 2020-09-21

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person VV Manager II, LLC 2. Issuer Name and Ticker or Trading Symbol Dyne Therapeutics, Inc. [ DYN] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 40 BROAD STREET, SUITE 201 3. Date of Earliest Transaction (MM/DD/YY) 09/21/2020 (Street) BOSTON, MA02109 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 09/21/2020 C 2,087,130 A 2,087,130 I See footnotes ( 2 ) ( 3 ) Common Stock 09/21/2020 P 792,995 A $ 19 2,880,125 I See footnotes ( 2 ) ( 3 ) Common Stock 09/21/2020 C 57,916 A 57,916 I See footnote ( 4 ) Common Stock 09/21/2020 P 22,005 A $ 19 79,921 I See footnote ( 4 )

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Series B Preferred Stock ( 1 ) 09/21/2020 C 6,922,803 ( 1 ) ( 1 ) Common Stock 2,087,130 $ 0 0 I See footnotes ( 2 ) ( 3 ) Series B Preferred Stock ( 1 ) 09/21/2020 C 192,102 ( 1 ) ( 1 ) Common Stock 57,916 $ 0 0 I See footnote ( 4 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other VV Manager II, LLC 40 BROAD STREET, SUITE 201 BOSTON, MA02109 X Vida Ventures II, LLC 40 BROAD STREET, SUITE 201 BOSTON, MA02109 X VIDA VENTURES II-A, LLC 40 BROAD STREET, SUITE 201 BOSTON, MA02109 X Signatures Vida Ventures II, LLC By: VV Manager II, LLC, its Manager, By: /s/ Stefan Vitorovic, its Managing Director 09/23/2020 Signature of Reporting Person Date Vida Ventures II-A, LLC By: VV Manager II, LLC, its Manager, By: /s/ Stefan Vitorovic, its Managing Director 09/23/2020 Signature of Reporting Person Date VV Manager II, LLC, By: /s/ Stefan Vitorovic, its Managing Director 09/23/2020 Signature of Reporting Person Date

Explanation of Responses:

( 1 )On September 21, 2020, the Series B Preferred Stock automatically converted into Common Stock on a 3.3169-for-one basis without payment of further consideration upon closing of the initial public offering of the Issuer's common stock. The shares had no expiration date. ( 2 )The shares are held directly by Vida Ventures II, LLC ("Vida II"). VV Manager II, LLC ("VV Manager II") is the manager of Vida II. Arie Belldegrun, Fred Cohen, and Leonard Potter are the members of the management committee of VV Manager II (the "Management Committee") and Stefan Vitorovic, Arjun Goyal, Helen Kim, Rajul Jain, and Joshua Kazam are the members of the investment committee of VV Manager II (the "Investment Committee"). ( 3 )(Continued from Footnote 2) Each of the Management Committee, the Investment Committee and the respective members thereof may be deemed to share voting and dispositive power over the shares held by Vida II. VV Manager II, the Management Committee, the Investment Committee and each member of each of the Management Committee and Investment Committee disclaims beneficial ownership over the securities held of record by Vida II and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interest therein. ( 4 )The shares are held directly by Vida Ventures II-A, LLC ("Vida II-A"). VV Manager II is the manager of Vida II-A. Each of the Management Committee ,the Investment Committee and the respective members thereof may be deemed to share voting and dispositive power over the shares held by Vida II-A. VV Manager II, the Management Committee, the Investment Committee and each member of each of the Management Committee and Investment Committee disclaims beneficial ownership over the securities held of record by Vida II-A and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interest therein.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

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