Were the Dyne Therapeutics (DYN) share sales by entities linked to Jason P. Rhodes pre-planned?

Yes. The filing states the shares were sold under a Rule 10b5-1 trading plan adopted on March 19, 2026. Such plans allow pre-arranged trading schedules, indicating the timing of these sales was set in advance rather than decided opportunistically.

Atlas funds linked to Dyne (DYN) director sell 504,695 shares

Q: How many Dyne Therapeutics (DYN) shares were sold in Jason P. Rhodes' latest Form 4?

Jason P. Rhodes reported affiliated entities selling 504,695 shares of Dyne Therapeutics common stock. These were open-market transactions across June 26 and June 29, 2026, and are reported as indirect holdings through various Atlas Venture funds.

Q: Who actually holds the Dyne Therapeutics (DYN) shares reported in Jason P. Rhodes' Form 4?

The shares are held by Atlas Venture Fund XI , Atlas Venture Opportunity Fund I and II , and related partnerships such as AVA XI LP . Rhodes is a member of related general partners and disclaims Section 16 beneficial ownership except for his pecuniary interest.

Filing Impact

(Very High)

Filing Sentiment

(Very Negative)

Form Type

Rhea-AI Filing Summary

Dyne Therapeutics, Inc. director Jason P. Rhodes reported that investment entities associated with him sold a total of 504,695 shares of common stock in open-market transactions on June 26 and June 29, 2026.

The shares were sold at weighted-average prices around $21.14–$21.28, within disclosed ranges from $21.00 up to $21.61, under a Rule 10b5-1 trading plan adopted on March 19, 2026. The transactions were executed by Atlas Venture and related funds, and Rhodes disclaims Section 16 beneficial ownership of these securities except to the extent of his pecuniary interest. Following the sales, individual Atlas-affiliated entities continue to report sizeable indirect holdings, including 4,579,456 and 1,396,475 shares of Dyne Therapeutics common stock.

Insider Trade Summary 10b5-1

Net Seller: 504,695 shares ($10,712,550)

Net Sell 7 txns

Insider Rhodes Jason P

Role null

Sold 504,695 shs ($10.71M)

Type	Security	Shares	Price	Value
Sale	Common Stock	102,969	$21.14	$2.18M
Sale	Common Stock	51,756	$21.14	$1.09M
Sale	Common Stock	40,702	$21.14	$860K
Sale	Common Stock	162,954	$21.28	$3.47M
Sale	Common Stock	81,903	$21.28	$1.74M
Sale	Common Stock	64,411	$21.28	$1.37M
holding	Common Stock	--	--	--

Holdings After Transaction: Common Stock — 4,476,487 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 $21.00 to $21.61 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 ranges set forth in footnotes (2) and (6). 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 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 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 $21.00 to $21.3247 inclusive. 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.

Key Figures

Total shares sold: 504,695 shares June 29 sale block 1: 40,702 shares at $21.14 June 29 sale block 2: 51,756 shares at $21.14 +4 more

7 metrics

Total shares sold 504,695 shares Net common-stock sales reported in this Form 4

June 29 sale block 1 40,702 shares at $21.14 Open-market sale of common stock on June 29, 2026

June 29 sale block 2 51,756 shares at $21.14 Open-market sale of common stock on June 29, 2026

June 29 sale block 3 102,969 shares at $21.14 Open-market sale of common stock on June 29, 2026

June 26 sale block 1 64,411 shares at $21.28 Open-market sale of common stock on June 26, 2026

Largest post-transaction holding 4,579,456 shares Indirect common-stock holding for one Atlas-affiliated entity

Second-largest post-transaction holding 1,396,475 shares Indirect common-stock holding for another Atlas-affiliated entity

Key Terms

Rule 10b5-1 trading plan, weighted average price, Section 16 beneficial ownership, pecuniary interest

4 terms

Rule 10b5-1 trading plan financial

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

A Rule 10b5-1 trading plan is a pre-arranged schedule that allows company insiders to buy or sell stock at specific times, even if they have inside information. It helps prevent accusations of unfair trading by making these transactions look planned and transparent, rather than sneaky or illegal.

weighted average price financial

"The price reported in Column 4 is a weighted average price. These securities were sold in multiple transactions..."

Weighted average price is the average price of a security where each trade or component is counted according to its size, so bigger trades pull the average more than smaller ones. Think of it like calculating the average cost of a grocery haul where items you bought more of have greater influence on the final per-item cost. Investors use it to understand the true average price paid or received, judge execution quality, and compare trading performance against market movement.

Section 16 beneficial ownership financial

"The Reporting Person is a member of AVA XI LLC and disclaims Section 16 beneficial ownership of such securities..."

pecuniary interest financial

"disclaims Section 16 beneficial ownership of such securities... except to the extent of his pecuniary interest therein, if any."

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Form 4 Insider Transactions: What Each Field Means →

Available on EDGAR 06/30/2026 - 07:05 PM Accepted by SEC EDGAR 06/30/2026 - 07:05 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)
06/26/2026

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	06/26/2026		S⁽¹⁾		162,954	D	$21.28⁽²⁾	4,579,456	I	See footnote⁽³⁾
Common Stock	06/26/2026		S⁽¹⁾		81,903	D	$21.28⁽²⁾	1,396,475	I	See footnote⁽⁴⁾
Common Stock	06/26/2026		S⁽¹⁾		64,411	D	$21.28⁽²⁾	1,016,633	I	See footnote⁽⁵⁾
Common Stock	06/29/2026		S⁽¹⁾		102,969	D	$21.14⁽⁶⁾	4,476,487	I	See footnote⁽³⁾
Common Stock	06/29/2026		S⁽¹⁾		51,756	D	$21.14⁽⁶⁾	1,344,719	I	See footnote⁽⁴⁾
Common Stock	06/29/2026		S⁽¹⁾		40,702	D	$21.14⁽⁶⁾	975,931	I	See footnote⁽⁵⁾
Common Stock								7,962	I	See footnote⁽⁷⁾

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 $21.00 to $21.61 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 ranges set forth in footnotes (2) and (6).

3. 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.

4. 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.

5. 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.

6. The price reported in Column 4 is a weighted average price. These securities were sold in multiple transactions at prices ranging from $21.00 to $21.3247 inclusive.

7. 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.

	/s/ Ommer Chohan, Attorney-in-Fact	06/30/2026
	** 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

How many Dyne Therapeutics (DYN) shares were sold in Jason P. Rhodes' latest Form 4?

Jason P. Rhodes reported affiliated entities selling 504,695 shares of Dyne Therapeutics common stock. These were open-market transactions across June 26 and June 29, 2026, and are reported as indirect holdings through various Atlas Venture funds.

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

The reported sales occurred at weighted-average prices around $21.14–$21.28 per share. Footnotes state the individual trades took place within ranges from $21.00 up to $21.61, and from $21.00 up to $21.3247 per share.

Who actually holds the Dyne Therapeutics (DYN) shares reported in Jason P. Rhodes' Form 4?

The shares are held by Atlas Venture Fund XI, Atlas Venture Opportunity Fund I and II, and related partnerships such as AVA XI LP. Rhodes is a member of related general partners and disclaims Section 16 beneficial ownership except for his pecuniary interest.

How many Dyne Therapeutics (DYN) shares remain held by the Atlas-affiliated entities after the reported sales?

After the transactions, individual Atlas-affiliated entities report sizeable indirect positions, including 4,579,456 shares and 1,396,475 shares of Dyne Therapeutics common stock. These figures reflect holdings for separate entities as disclosed in the post-transaction ownership columns.

Does Jason P. Rhodes' Form 4 indicate any derivative security exercises for Dyne Therapeutics (DYN)?

No derivative exercises are shown in this Form 4; all listed trades involve common stock as non-derivative securities. The derivative summary section is empty, indicating no options, warrants, or other derivatives were exercised in the reported transactions.