Dyne Therapeutics director-linked funds sell 106K shares

Dyne Therapeutics, Inc. reported that investment entities associated with director Jason P. Rhodes sold a total of 106,723 shares of its common stock in open-market transactions.

Rhea-AI Filing Summary

Dyne Therapeutics, Inc. reported that investment entities associated with director Jason P. Rhodes sold a total of 106,723 shares of its common stock in open-market transactions. The sales occurred on May 4–6, 2026 at weighted average prices around $18.00–$18.18 per share under a Rule 10b5-1 trading plan.

The trades were executed by Atlas Venture-managed funds and related partnerships that hold Dyne shares indirectly for investors. After these transactions, the entities still hold multi-million-share positions in Dyne across several funds, while Rhodes disclaims beneficial ownership beyond any pecuniary interest.

Insider Trade Summary 10b5-1

Net Seller: 106,723 shares

Net Sell 12 txns

Insider Rhodes Jason P

Role Director

Sold 106,723 shs ($1.94M)

Type	Security	Shares	Price	Value
Sale	Common Stock	21,926	$18.18	$399K
Sale	Common Stock	43,621	$18.18	$793K
Sale	Common Stock	428	$18.18	$8K
Sale	Common Stock	17,244	$18.18	$313K
Sale	Common Stock	3,056	$18.03	$55K
Sale	Common Stock	6,081	$18.03	$110K
Sale	Common Stock	60	$18.03	$1K
Sale	Common Stock	2,403	$18.03	$43K
Sale	Common Stock	3,136	$18.00	$56K
Sale	Common Stock	6,241	$18.00	$112K
Sale	Common Stock	61	$18.00	$1K
Sale	Common Stock	2,466	$18.00	$44K

Holdings After Transaction: Common Stock — 1,136,810 shares (Indirect, See footnote)

Footnotes (8)

1. F1. Shares were sold pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on March 19, 2026.
2. F2. 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 $18.0206 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. F3. 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. F4. 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. F5. 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. F6. 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. F7. 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 $18.0831 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. F8. 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 $18.89 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.

Key Figures

Total shares sold: 106,723 shares Sale price range (set 1): $18.00–$18.0206 per share Sale price range (set 2): $18.00–$18.0831 per share +5 more

8 metrics

Total shares sold 106,723 shares Open-market sales by Atlas Venture entities on May 4–6, 2026

Sale price range (set 1) $18.00–$18.0206 per share Weighted-average range for one group of transactions

Sale price range (set 2) $18.00–$18.0831 per share Weighted-average range for another transaction group

Sale price range (set 3) $18.00–$18.89 per share Weighted-average range for additional sales

Remaining holding in one fund 4,883,494 shares Post-transaction indirect holding for an Atlas Venture entity

Remaining holding in second fund 1,549,288 shares Post-transaction indirect holding for another Atlas Venture entity

Remaining holding in third fund 1,136,810 shares Post-transaction indirect holding in a separate Atlas-related entity

Small remaining indirect block 7,962 shares Post-transaction balance in a smaller Atlas-related account

Key Terms

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

5 terms

Rule 10b5-1 trading plan financial

"Shares were sold pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person"

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.

Section 16 beneficial ownership financial

"disclaims Section 16 beneficial ownership of such securities held by AVOF II"

weighted average price financial

"The price reported in Column 4 is a weighted average price"

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.

pecuniary interest financial

"except to the extent of his pecuniary interest therein, if any"

open-market sale financial

"transaction_action": "open-market sale""

An open-market sale is when a shareholder sells existing shares directly on a public exchange to any willing buyer, rather than through a private deal. Think of it like putting goods on a busy market stall where price is set by supply and demand; for investors it matters because such sales increase available supply, can put short-term downward pressure on the stock price, and signal changes in liquidity or investor confidence.

FAQ

What insider transactions did Dyne Therapeutics (DYN) disclose in this Form 4?

Dyne Therapeutics disclosed that entities associated with director Jason P. Rhodes sold 106,723 common shares. The open-market transactions occurred on May 4–6, 2026 at weighted average prices near $18 per share, reflecting planned portfolio activity rather than a new company financing.

Who actually sold the Dyne Therapeutics (DYN) shares reported for Jason P. Rhodes?

The reported sales were made by Atlas Venture-managed funds and related partnerships, not by Jason P. Rhodes personally. Footnotes state the shares are held by entities such as Atlas Venture Opportunity Fund II and Atlas Venture Fund XI, with Rhodes disclaiming Section 16 beneficial ownership except for any pecuniary interest.

Were the Dyne Therapeutics (DYN) insider sales made under a Rule 10b5-1 plan?

Yes. A footnote explains the shares were sold pursuant to a Rule 10b5-1 trading plan adopted by the reporting person. Such plans pre-arrange trading instructions, indicating these sales were scheduled in advance rather than timed in response to short-term developments at Dyne Therapeutics.

What prices were received for the Dyne Therapeutics (DYN) insider share sales?

Reported prices are weighted averages, with transactions on different days executed in tight ranges. Footnotes note sales between $18.00 and $18.0206, $18.00 and $18.0831, and $18.00 and $18.89 per share, reflecting multiple small trades around the reported average prices.

How many Dyne Therapeutics (DYN) shares do the Atlas Venture entities still hold after these sales?

Post-transaction, the filing shows remaining indirect holdings such as 4,883,494 shares, 1,549,288 shares, 1,136,810 shares, and 7,962 shares in different Atlas Venture funds and partnerships. These figures indicate the entities continue to own sizeable positions in Dyne Therapeutics after the reported sales.

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

No. Footnotes state the shares are owned directly by various Atlas Venture funds and partnerships. Rhodes is a member of their general partners and explicitly disclaims Section 16 beneficial ownership of those securities, except to the extent of his pecuniary interest in the investment entities.

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Accepted by SEC EDGAR 05/06/2026 - 05:09 PM Learn about SEC filing dates

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).

X

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)
05/04/2026

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)
			Code	V	Amount	(A) or (D)	Price
Common Stock	05/04/2026		S(1)		3,136	D	$18(2)	1,574,270	I	See footnote(3)
Common Stock	05/04/2026		S(1)		6,241	D	$18(2)	4,933,196	I	See footnote(4)
Common Stock	05/04/2026		S(1)		61	D	$18(2)	8,450	I	See footnote(5)
Common Stock	05/04/2026		S(1)		2,466	D	$18(2)	1,156,457	I	See footnote(6)
Common Stock	05/05/2026		S(1)		3,056	D	$18.03(7)	1,571,214	I	See footnote(3)
Common Stock	05/05/2026		S(1)		6,081	D	$18.03(7)	4,927,115	I	See footnote(4)
Common Stock	05/05/2026		S(1)		60	D	$18.03(7)	8,390	I	See footnote(5)
Common Stock	05/05/2026		S(1)		2,403	D	$18.03(7)	1,154,054	I	See footnote(6)
Common Stock	05/06/2026		S(1)		21,926	D	$18.18(8)	1,549,288	I	See footnote(3)
Common Stock	05/06/2026		S(1)		43,621	D	$18.18(8)	4,883,494	I	See footnote(4)
Common Stock	05/06/2026		S(1)		428	D	$18.18(8)	7,962	I	See footnote(5)
Common Stock	05/06/2026		S(1)		17,244	D	$18.18(8)	1,136,810	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)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

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 $18.00 to $18.0206 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 $18.00 to $18.0831 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 $18.89 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	05/06/2026
	** 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)