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Dyne Therapeutics (DYN) director's preset stock sale via Atlas funds

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

Rhea-AI Filing Summary

Dyne Therapeutics director Jason P. Rhodes reported indirect sales of 2,586,928 shares of Common Stock of DYN on August 13–14, 2026. The shares were sold primarily by Atlas Venture-affiliated funds at weighted average prices around $25–$26.20 per share, pursuant to a Rule 10b5-1 trading plan adopted on July 13, 2026. The footnotes state that the shares are held by various Atlas Venture funds and partnerships, and Rhodes disclaims Section 16 beneficial ownership except to the extent of his pecuniary interest.

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Insider Rhodes Jason P
Role Director
Sold 2,586,928 shs ($65.18M)
Type Security Shares Price Value
Sale Common Stock F1, F6, F3 1,359,674 $25.00 $33.99M
Sale Common Stock F1, F6, F4 478,377 $25.00 $11.96M
Sale Common Stock F1, F6, F5 322,465 $25.00 $8.06M
Sale Common Stock F1, F2, F3 268,354 $26.20 $7.03M
Sale Common Stock F1, F2, F4 94,415 $26.20 $2.47M
Sale Common Stock F1, F2, F5 63,643 $26.20 $1.67M
holding Common Stock F7 -- -- --
Holdings After Transaction: Common Stock — 431,908 shares (Indirect, See footnote)
Footnotes (7)
  1. F1. Shares were sold pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on July 13, 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 $25.8788 to $26.48 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. F3. 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. F4. 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. F5. 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. F6. The price reported in Column 4 is a weighted average price. These securities were sold in multiple transactions at prices ranging from $25.00 to $25.8916 inclusive.
  7. F7. 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 2,586,928 shares Aggregate sellShares across six non-derivative sales reported for August 13–14, 2026
Sale dates August 13–14, 2026 Transaction dates for reported common stock sales
Per-share price (row level) $25.00 per share Price field for August 14, 2026 sales, footnote-qualified as weighted average
Per-share price (row level) $26.20 per share Price field for August 13, 2026 sales, footnote-qualified as weighted average
Weighted price range (Footnote 2) $25.8788–$26.48 Range for multiple transactions referenced in Footnote (2)
Weighted price range (Footnote 6) $25.00–$25.8916 Range for multiple transactions referenced in Footnote (6)
10b5-1 plan adoption date July 13, 2026 Date Jason P. Rhodes adopted the Rule 10b5-1 trading plan used for these sales
Rule 10b5-1 trading plan regulatory
"Shares were sold pursuant to a Rule 10b5-1 trading plan adopted"
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"
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
"disclaims Section 16 beneficial ownership of such securities"
pecuniary interest financial
"except to the extent of his pecuniary interest therein, if any"

FAQ

What did DYN director Jason P. Rhodes report in this Form 4 filing?
Jason P. Rhodes reported indirect sales of 2,586,928 DYN common shares on August 13–14, 2026. The sales were executed by Atlas Venture-affiliated funds at weighted average prices in the mid‑$20s per share under a Rule 10b5-1 trading plan.

At what prices were the DYN shares sold in this Form 4 for DYN?
Reported sales occurred at weighted average prices, with ranges of $25.00–$25.8916 and $25.8788–$26.48 per share. Some rows list $25.00 and $26.20, but the filing notes aggregated, multiple‑transaction pricing within those ranges.

Were the DYN share sales by Jason P. Rhodes under a Rule 10b5-1 plan?
Yes. The filing states the shares were sold pursuant to a Rule 10b5-1 trading plan adopted by Jason P. Rhodes on July 13, 2026. This indicates a pre‑arranged trading program rather than discretionary, real‑time trading decisions.

Did Jason P. Rhodes sell DYN shares directly or indirectly in this filing?
All reported sales are labeled as indirect ownership and tied to Atlas Venture funds and partnerships. Footnotes explain that these entities, not Rhodes personally, hold the shares, and he disclaims Section 16 beneficial ownership beyond any pecuniary interest.

Which entities associated with Jason P. Rhodes sold DYN shares in this Form 4?
The filing attributes holdings and sales to Atlas Venture Fund XI, L.P., Atlas Venture Opportunity Fund I, L.P., and Atlas Venture Opportunity Fund II, L.P., as well as AVA XI LP, with Atlas general partner entities managing these funds.

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Form 4 Insider Transactions: What Each Field Means →
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.
1560 TRAPELO ROAD
(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)
08/13/2026		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 Stock08/13/2026S(1)268,354D$26.2(2)3,801,128ISee footnote(3)
Common Stock08/13/2026S(1)94,415D$26.2(2)1,045,735ISee footnote(4)
Common Stock08/13/2026S(1)63,643D$26.2(2)751,411ISee footnote(5)
Common Stock08/14/2026S(1)1,359,674D$25(6)2,441,454ISee footnote(3)
Common Stock08/14/2026S(1)478,377D$25(6)567,358ISee footnote(4)
Common Stock08/14/2026S(1)322,465D$25(6)428,946ISee footnote(5)
Common Stock2,962ISee 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)
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 July 13, 2026.
2. The price reported in Column 4 is a weighted average price. These securities were sold in multiple transactions at prices ranging from $25.8788 to $26.48 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 $25.00 to $25.8916 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-Fact08/17/2026
** 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