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Dyne Therapeutics (DYN) director-linked Atlas funds sell 777K shares under 10b5-1 plan

Filing Impact
(Very High)
Filing Sentiment
(Very Negative)
Form Type
4

Rhea-AI Filing Summary

Dyne Therapeutics, Inc. director-affiliated venture funds completed open-market sales of a combined 777,451 shares of common stock on July 6–7, 2026. The trades, at weighted-average prices between about $22.79 and $23.62 per share, were executed under a Rule 10b5-1 trading plan adopted on March 19, 2026.

The shares were sold by Atlas-managed funds, including Atlas Venture Fund XI and Atlas Venture Opportunity Funds, in which director Jason P. Rhodes participates through general partner entities. He disclaims Section 16 beneficial ownership beyond any pecuniary interest. After the transactions, these funds continue to hold multimillion-share positions, such as 4,099,069 shares in one Atlas vehicle.

Positive

  • None.

Negative

  • None.
Insider Rhodes Jason P
Role Director
Sold 777,451 shs ($17.86M)
Type Security Shares Price Value
Sale Common Stock 124,379 $23.17 $2.88M
Sale Common Stock 29,587 $23.62 $699K
Sale Common Stock 62,543 $23.17 $1.45M
Sale Common Stock 14,844 $23.62 $351K
Sale Common Stock 49,193 $23.17 $1.14M
Sale Common Stock 11,665 $23.62 $276K
Sale Common Stock 5,000 $23.61 $118K
Sale Common Stock 253,039 $22.79 $5.77M
Sale Common Stock 127,182 $22.79 $2.90M
Sale Common Stock 100,019 $22.79 $2.28M
Holdings After Transaction: Common Stock — 4,099,069 shares (Indirect, See footnote)
Footnotes (1)
  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 $22.4163 to $23.25 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) through (8). 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 $22.4572 to $23.4553 inclusive. The price reported in Column 4 is a weighted average price. These securities were sold in multiple transactions at prices ranging from $23.46 to $23.8628 inclusive. The price reported in Column 4 is a weighted average price. These securities were sold in multiple transactions at prices ranging from $23.50 to $23.794 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.
Total shares sold 777,451 shares Net open-market sales on July 6–7, 2026
July 6 sale price $22.7900 per share One tranche of indirect open-market sales
July 7 sale price (example) $23.1700 per share One of several open-market sale prices
Highest reported average range low $23.46 per share Lower end of one weighted-average price range
Largest post-sale holding 4,099,069 shares Shares of Dyne common stock held by one Atlas fund after sales
Another post-sale holding 1,154,994 shares Post-transaction balance for another Atlas-affiliated holder
10b5-1 plan adoption date March 19, 2026 Date the trading plan governing these sales was adopted
Rule 10b5-1 trading plan regulatory
"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 regulatory
"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 held by Atlas Venture Fund XI, except to the extent of his pecuniary interest therein, if any."
general partner financial
"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."
A general partner is the person or firm that runs an investment partnership and legally represents it — they make the day-to-day decisions, choose which assets to buy or sell, and are responsible for the partnership’s obligations. Investors care because the general partner’s judgment, risk-taking and fee and profit-sharing arrangements determine both the potential returns and the level of exposure to losses; think of the GP as the ship’s captain whose skill and honesty shape the voyage’s outcome.
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Form 4 Insider Transactions: What Each Field Means →

FAQ

What did Dyne Therapeutics (DYN) disclose in Jason Rhodes' latest Form 4?
Dyne Therapeutics reported that venture funds affiliated with director Jason P. Rhodes sold a total of 777,451 shares of common stock in open-market transactions on July 6–7, 2026, at weighted-average prices around $22.79–$23.62 per share.

Were the Dyne Therapeutics (DYN) insider sales made under a Rule 10b5-1 plan?
Yes. The filing states the shares were sold under a Rule 10b5-1 trading plan adopted on March 19, 2026. Such pre-arranged plans are designed to allow insiders to sell shares on a scheduled basis, reducing the impact of timing decisions.

Who actually sold Dyne Therapeutics (DYN) shares in this Form 4 for Jason Rhodes?
The sales were made by Atlas Venture Fund XI and Atlas Venture Opportunity Funds I and II, plus AVA XI LP, not by Rhodes personally. He is a member of their general partner entities and disclaims Section 16 beneficial ownership except for any pecuniary interest.

How many Dyne Therapeutics (DYN) shares did the director-affiliated funds sell and at what prices?
Across ten open-market transactions, the Atlas-affiliated funds sold 777,451 shares of Dyne Therapeutics common stock. Reported weighted-average sale prices ranged from approximately $22.4163 to $23.8628 per share, as detailed in several weighted-average price footnotes.

Do the funds linked to Dyne Therapeutics (DYN) director Jason Rhodes still hold shares after these sales?
Yes. Post-transaction balances show continued large positions, including 4,099,069 shares in one Atlas fund and over 1.1 million shares in another. These holdings reflect the shares remaining after the July 6–7, 2026 open-market sales.

How does Jason Rhodes describe his ownership interest in Dyne Therapeutics (DYN) through Atlas funds?
The filing explains that the shares are held by Atlas-managed funds and general partner entities. Jason Rhodes is a member of these general partners and disclaims Section 16 beneficial ownership of the funds’ Dyne shares, except to the extent of any pecuniary interest he may have.
SEC Form 4
FORM 4UNITED 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)
XDirector10% Owner
Officer (give title below)Other (specify below)
2a. Foreign Trading Symbol
3. Date of Earliest Transaction (Month/Day/Year)
07/06/2026		6. Individual or Joint/Group Filing (Check Applicable Line)
XForm 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)
CodeVAmount(A) or (D)Price
Common Stock07/06/2026S(1)253,039D$22.79(2)4,223,448ISee footnote(3)
Common Stock07/06/2026S(1)127,182D$22.79(2)1,217,537ISee footnote(4)
Common Stock07/06/2026S(1)100,019D$22.79(2)875,912ISee footnote(5)
Common Stock07/07/2026S(1)124,379D$23.17(6)4,099,069ISee footnote(3)
Common Stock07/07/2026S(1)29,587D$23.62(7)4,069,482ISee footnote(3)
Common Stock07/07/2026S(1)62,543D$23.17(6)1,154,994ISee footnote(4)
Common Stock07/07/2026S(1)14,844D$23.62(7)1,140,150ISee footnote(4)
Common Stock07/07/2026S(1)49,193D$23.17(6)826,719ISee footnote(5)
Common Stock07/07/2026S(1)11,665D$23.62(7)815,054ISee footnote(5)
Common Stock07/07/2026S5,000D$23.61(8)2,962ISee footnote(9)
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)
CodeV(A)(D)Date ExercisableExpiration DateTitleAmount 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 $22.4163 to $23.25 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) through (8).
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 $22.4572 to $23.4553 inclusive.
7. The price reported in Column 4 is a weighted average price. These securities were sold in multiple transactions at prices ranging from $23.46 to $23.8628 inclusive.
8. The price reported in Column 4 is a weighted average price. These securities were sold in multiple transactions at prices ranging from $23.50 to $23.794 inclusive.
9. 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-Fact07/08/2026
** Signature of Reporting PersonDate
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