SEC Form 4

FORM 4		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 or Section 30(h) of the Investment Company Act of 1940	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response: 0.5
X	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person* RA CAPITAL MANAGEMENT, L.P. (Last) (First) (Middle) 200 BERKELEY STREET 18TH FLOOR (Street) BOSTON MA 02116 (City) (State) (Zip)	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)
	3. Date of Earliest Transaction (Month/Day/Year) 09/21/2020
	4. If Amendment, Date of Original Filed (Month/Day/Year)	6. Individual or Joint/Group Filing (Check Applicable Line) Form filed by One Reporting Person X Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	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		2,145,045	A	(1)	2,145,045(2)	I	See footnote(3)(4)
Common Stock	09/21/2020		P		660,000(5)	A	$19	2,805,045(6)	I	See footnote(3)(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 (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	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 (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (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: 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			7,114,905	(1)	(1)	Common Stock	2,145,045(2)	$0	0	I	See footnote(3)(4)

1. Name and Address of Reporting Person* RA CAPITAL MANAGEMENT, L.P. (Last) (First) (Middle) 200 BERKELEY STREET 18TH FLOOR (Street) BOSTON MA 02116 (City) (State) (Zip)

1. Name and Address of Reporting Person* Kolchinsky Peter (Last) (First) (Middle) 200 BERKELEY STREET 18TH FLOOR (Street) BOSTON MA 02116 (City) (State) (Zip)

1. Name and Address of Reporting Person* Shah Rajeev M. (Last) (First) (Middle) 200 BERKELEY STREET 18TH FLOOR (Street) BOSTON MA 02116 (City) (State) (Zip)

Explanation of Responses:

1. 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. Includes (a) 1,458,068 shares held by RA Capital Healthcare Fund L.P. (the "Fund"), (b) 150,716 shares held in a separately managed account (the "Account") and (c) 536,261 shares held by RA Capital Nexus Fund, L.P. (the "Nexus Fund").

3. RA Capital Management, L.P. (the "Adviser") is the investment manager for the Fund, the Nexus Fund and the Account. The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. The Adviser, the Adviser GP, Dr. Kolchinsky, and Mr. Shah may be deemed indirect beneficial owners of the reported securities for purposes of Section 13(d) of the Securities Exchange Act of 1934 (the "Act").

4. They disclaim beneficial ownership of any of the reported securities for the purpose of determining whether they are subject to Section 16 of the Act, however, in reliance on Rule 16a-1(a)(1)(v) and (vii). To the extent that they might be deemed subject to Section 16, they disclaim beneficial ownership of securities held by the Fund and the Nexus Fund for purposes of Rule 16a-1(a)(2), except to the extent of their pecuniary interest therein, and disclaim any pecuniary interest in securities held in the Account for purposes of Rule 16a-1(a)(2).

5. Includes (a) 570,747 shares held by the Fund, (b) 57,453 shares held by the Account, and (c) 31,800 shares held by the Nexus Fund, in each case acquired in the Issuer's initial public offering.

6. Includes (a) 2,028,815 shares held by the Fund, (b) 208,169 shares held by the Account, and (c) 568,061 shares held by the Nexus Fund.

	/s/ Peter Kolchinsky, Manager of RA Capital Management, L.P.	09/23/2020
	/s/ Peter Kolchinsky, individually	09/23/2020
	/s/ Rajeev Shah, individually	09/23/2020
	** Signature of Reporting Person	Date
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* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
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