[Form 4] Dyne Therapeutics, Inc. Insider Trading Activity

Filing Impact

(Very High)

Filing Sentiment

(Very Negative)

Form Type

Rhea-AI Filing Summary

Dyne Therapeutics director-affiliated funds reported open-market sales of 384,549 shares of common stock at prices generally around $18–$19 per share. The trades on April 23–27 were executed under a Rule 10b5-1 trading plan adopted on March 19, 2026.

The shares were sold by Atlas Venture funds and related partnerships, including Atlas Venture Opportunity Fund II, Atlas Venture Fund XI, AVA XI LP, and Atlas Venture Opportunity Fund I. Jason P. Rhodes is a member of the relevant general partner entities and disclaims Section 16 beneficial ownership except to the extent of any pecuniary interest.

Insider Trade Summary 10b5-1

Net Seller: 384,549 shares ($7,101,120)

Net Sell 12 txns

Insider Rhodes Jason P

Role null

Sold 384,549 shs ($7.10M)

Type	Security	Shares	Price	Value
Sale	Common Stock	45,709	$18.15	$830K
Sale	Common Stock	90,943	$18.15	$1.65M
Sale	Common Stock	894	$18.15	$16K
Sale	Common Stock	35,947	$18.15	$652K
Sale	Common Stock	36,345	$18.48	$672K
Sale	Common Stock	72,310	$18.48	$1.34M
Sale	Common Stock	710	$18.48	$13K
Sale	Common Stock	28,583	$18.48	$528K
Sale	Common Stock	19,261	$19.19	$370K
Sale	Common Stock	38,322	$19.19	$735K
Sale	Common Stock	377	$19.19	$7K
Sale	Common Stock	15,148	$19.19	$291K

Holdings After Transaction: Common Stock — 1,637,302 shares (Indirect, See footnote)

Footnotes (1)

Shares were sold pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on March 19, 2026. The price reported in Column 4 is a weighted average price. These securities were sold in multiple transactions at prices ranging from $19.00 to $19.45 inclusive. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of securities sold at each separate price within the range set forth in this footnote. The shares are owned directly by Atlas Venture Opportunity Fund II, L.P. ("AVOF II"). Atlas Venture Associates Opportunity II, LP ("AVAO II LP") is the general partner of AVOF II. Atlas Venture Associates Opportunity II, LLC ("AVAO II LLC") is the general partner of AVAO II LP. The Reporting Person is a member of AVAO II LLC and disclaims Section 16 beneficial ownership of such securities held by AVOF II, except to the extent of his pecuniary interest therein, if any. The shares are held directly by Atlas Venture Fund XI, L.P. ("Atlas Venture Fund XI"). The general partner of Atlas Venture Fund XI is Atlas Venture Associates XI, L.P. ("AVA XI LP"). Atlas Venture Associates XI, LLC ("AVA XI LLC") is the general partner of AVA XI LP. The Reporting Person is a member of AVA XI LLC and disclaims Section 16 beneficial ownership of such securities held by Atlas Venture Fund XI, except to the extent of his pecuniary interest therein, if any. The shares are held directly by AVA XI LP. AVA XI LLC is the general partner of AVA XI LP. The Reporting Person is a member of AVA XI LLC and disclaims Section 16 beneficial ownership of the securities held by AVA XI LP, except to the extent of his pecuniary interest therein, if any. The shares are held directly by Atlas Venture Opportunity Fund I, L.P. ("AVOF I"). The general partner of AVOF I is Atlas Venture Associates Opportunity I, L.P. ("AVAO I LP"). Atlas Venture Associates Opportunity I, LLC ("AVAO I LLC") is the general partner of AVAO I LP. The Reporting Person is a member of AVAO I LLC and disclaims Section 16 beneficial ownership of such securities held by AVOF I, except to the extent of his pecuniary interest therein, if any. The price reported in Column 4 is a weighted average price. These securities were sold in multiple transactions at prices ranging from $18.1272 to $19.035 inclusive. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of securities sold at each separate price within the range set forth in this footnote. The price reported in Column 4 is a weighted average price. These securities were sold in multiple transactions at prices ranging from $18.00 to $18.445 inclusive. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of securities sold at each separate price within the range set forth in this footnote.

Form 4 Insider Transactions: What Each Field Means →

04/27/2026 - 06:15 PM

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

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

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Rhodes Jason P

(Last)

(First)

(Middle)

C/O DYNE THERAPEUTICS, INC.

830 WINTER ST.

(Street)

WALTHAM

MASSACHUSETTS

02451

(City)

(State)

(Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
Dyne Therapeutics, Inc. [ DYN ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director	10% Owner
	Officer (give title below)	Other (specify below)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
04/23/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

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)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Common Stock	04/23/2026		S⁽¹⁾		19,261	D	$19.19⁽²⁾	1,719,356	I	See footnote⁽³⁾
Common Stock	04/23/2026		S⁽¹⁾		38,322	D	$19.19⁽²⁾	5,221,857	I	See footnote⁽⁴⁾
Common Stock	04/23/2026		S⁽¹⁾		377	D	$19.19⁽²⁾	11,286	I	See footnote⁽⁵⁾
Common Stock	04/23/2026		S⁽¹⁾		15,148	D	$19.19⁽²⁾	1,270,556	I	See footnote⁽⁶⁾
Common Stock	04/24/2026		S⁽¹⁾		36,345	D	$18.48⁽⁷⁾	1,683,011	I	See footnote⁽³⁾
Common Stock	04/24/2026		S⁽¹⁾		72,310	D	$18.48⁽⁷⁾	5,149,547	I	See footnote⁽⁴⁾
Common Stock	04/24/2026		S⁽¹⁾		710	D	$18.48⁽⁷⁾	10,576	I	See footnote⁽⁵⁾
Common Stock	04/24/2026		S⁽¹⁾		28,583	D	$18.48⁽⁷⁾	1,241,973	I	See footnote⁽⁶⁾
Common Stock	04/27/2026		S⁽¹⁾		45,709	D	$18.15⁽⁸⁾	1,637,302	I	See footnote⁽³⁾
Common Stock	04/27/2026		S⁽¹⁾		90,943	D	$18.15⁽⁸⁾	5,058,604	I	See footnote⁽⁴⁾
Common Stock	04/27/2026		S⁽¹⁾		894	D	$18.15⁽⁸⁾	9,682	I	See footnote⁽⁵⁾
Common Stock	04/27/2026		S⁽¹⁾		35,947	D	$18.15⁽⁸⁾	1,206,026	I	See footnote⁽⁶⁾

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)
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)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)

Explanation of Responses:

1. Shares were sold pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on March 19, 2026.

2. The price reported in Column 4 is a weighted average price. These securities were sold in multiple transactions at prices ranging from $19.00 to $19.45 inclusive. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of securities sold at each separate price within the range set forth in this footnote.

3. The shares are owned directly by Atlas Venture Opportunity Fund II, L.P. ("AVOF II"). Atlas Venture Associates Opportunity II, LP ("AVAO II LP") is the general partner of AVOF II. Atlas Venture Associates Opportunity II, LLC ("AVAO II LLC") is the general partner of AVAO II LP. The Reporting Person is a member of AVAO II LLC and disclaims Section 16 beneficial ownership of such securities held by AVOF II, except to the extent of his pecuniary interest therein, if any.

4. The shares are held directly by Atlas Venture Fund XI, L.P. ("Atlas Venture Fund XI"). The general partner of Atlas Venture Fund XI is Atlas Venture Associates XI, L.P. ("AVA XI LP"). Atlas Venture Associates XI, LLC ("AVA XI LLC") is the general partner of AVA XI LP. The Reporting Person is a member of AVA XI LLC and disclaims Section 16 beneficial ownership of such securities held by Atlas Venture Fund XI, except to the extent of his pecuniary interest therein, if any.

5. The shares are held directly by AVA XI LP. AVA XI LLC is the general partner of AVA XI LP. The Reporting Person is a member of AVA XI LLC and disclaims Section 16 beneficial ownership of the securities held by AVA XI LP, except to the extent of his pecuniary interest therein, if any.

6. The shares are held directly by Atlas Venture Opportunity Fund I, L.P. ("AVOF I"). The general partner of AVOF I is Atlas Venture Associates Opportunity I, L.P. ("AVAO I LP"). Atlas Venture Associates Opportunity I, LLC ("AVAO I LLC") is the general partner of AVAO I LP. The Reporting Person is a member of AVAO I LLC and disclaims Section 16 beneficial ownership of such securities held by AVOF I, except to the extent of his pecuniary interest therein, if any.

7. The price reported in Column 4 is a weighted average price. These securities were sold in multiple transactions at prices ranging from $18.1272 to $19.035 inclusive. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of securities sold at each separate price within the range set forth in this footnote.

8. The price reported in Column 4 is a weighted average price. These securities were sold in multiple transactions at prices ranging from $18.00 to $18.445 inclusive. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of securities sold at each separate price within the range set forth in this footnote.

	/s/ Ommer Chohan, Attorney-in-Fact	04/27/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)

Source: View Original Filing on SEC EDGAR

FAQ

What did the Dyne Therapeutics (DYN) Form 4 filing report for Jason P. Rhodes?

The Form 4 reports open-market sales totaling 384,549 Dyne Therapeutics shares by investment funds associated with director Jason P. Rhodes. All transactions involved common stock and were executed over several days at prices in the high teens per share.

Who actually sold the Dyne Therapeutics (DYN) shares in this Form 4?

The shares were sold by Atlas Venture investment funds and related partnerships, including Atlas Venture Opportunity Fund II, Atlas Venture Fund XI, AVA XI LP, and Atlas Venture Opportunity Fund I. Rhodes is a member of the general partner entities rather than the direct shareowner.

Were the Dyne Therapeutics (DYN) insider sales pre-planned under Rule 10b5-1?

Yes. The filing states the shares were sold under a Rule 10b5-1 trading plan adopted by the reporting person on March 19, 2026. Such plans schedule trades in advance, making the timing more routine rather than discretionary.

At what prices were the Dyne Therapeutics (DYN) shares sold in this Form 4?

The reported weighted average prices were around $18–$19 per share. Footnotes note multiple trades, including ranges of $19.00–$19.45, $18.1272–$19.035, and $18.00–$18.445, with detailed price breakdowns available on request from the issuer or SEC staff.

How many Dyne Therapeutics (DYN) shares do the reporting funds still hold after these sales?

The Form 4 shows multi-million share positions remaining in several Atlas funds. Examples include 5,058,604 shares following one sale and 5,149,547 shares after another, indicating continued sizeable indirect holdings associated with the reporting structures.

Does Jason P. Rhodes claim full beneficial ownership of the Dyne (DYN) shares sold?

No. The Form 4 repeatedly states that Rhodes disclaims Section 16 beneficial ownership of shares held by the Atlas funds and partnerships, except to the extent of his pecuniary interest through his membership in the general partner entities.