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

Rhea-AI Filing Summary

Insider sales to satisfy RSU tax withholding reduced Johanna Friedl-Naderer's direct holdings in Dyne Therapeutics (DYN). On 09/04/2025 she reported automatic sales of 894 shares at a weighted average price of $13.27 (transactions ranged $13.08–$13.50) tied to RSUs that vested from a September 3, 2024 grant. On 09/05/2025 she reported automatic sales of 144 shares at $13.41 related to RSUs from a December 4, 2024 grant.

After these transactions her reported beneficial ownership declined from 95,017 to 94,873 shares. The filings state the sales were automatic to satisfy tax withholding and executed under a binding arrangement consistent with a Rule 10b5-1 plan; 74,514 RSUs remain unvested.

Positive

• Sales were executed under a documented plan consistent with Rule 10b5-1, indicating pre-arranged, non-discretionary trades
• Full disclosure of weighted-average pricing and offer to provide detailed per-trade prices enhances transparency
• Large unvested RSU balance (74,514 shares) indicates ongoing alignment with company performance

Negative

• Reported beneficial ownership decreased from 95,017 to 94,873 shares following the automatic sales
• Cashless share sales to cover tax withholding reduce immediate economic stake, though impact appears small

Insights

Corporate Governance Expert

TL;DR: Routine, pre-arranged insider sales for tax withholding; governance and disclosure appear compliant.

The Form 4 shows automatic disposition of equity to satisfy tax obligations upon RSU vesting, executed under a documented arrangement referenced as consistent with Rule 10b5-1. The reporting includes weighted-average pricing and a commitment to provide granular price breakdowns on request, which supports transparency. The remaining unvested RSU balance is disclosed, allowing stakeholders to see continued alignment via future equity vesting. There is no indication of discretionary trading or other governance concerns in the filing.

Executive Compensation Analyst

TL;DR: Sales are administrative (tax withholding) and represent a small change in economic ownership.

The transactions—894 shares and 144 shares—are explicitly tied to tax withholding on RSU vesting from two separate grants. The reported prices and the note that the sales were automatic indicate these were not performance-driven sales. The existence of 74,514 unvested RSUs suggests significant future equity compensation remains, preserving long-term incentive alignment despite the modest decline in reported beneficial ownership.

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^*

Friedl-Naderer Johanna

(Last) (First) (Middle)

C/O DYNE THERAPEUTICS, INC.

1560 TRAPELO ROAD

(Street)

WALTHAM MA 02451

(City) (State) (Zip)

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

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

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

3. Date of Earliest Transaction (Month/Day/Year)
09/04/2025

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

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

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

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	09/04/2025		S(1)		894	D	$13.27(2)	95,017	D
Common Stock	09/05/2025		S(3)		144	D	$13.41	94,873(4)	D

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. Represents shares automatically sold by the Reporting Person to satisfy tax withholding obligations in connection with the vesting of restricted stock units granted to the Reporting Person on September 3, 2024. The automatic sale of the Reporting Person's shares is provided for in a restricted stock unit agreement constituting a "binding contract" consistent with the affirmative defense to liability under Rule 10b5-1 and the sale does not represent a discretionary trade by the Reporting Person.

2. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $13.08 to $13.50, inclusive. The Reporting Person undertakes 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 shares sold at each separate price within the range set forth in this footnote of this Form 4.

3. Represents shares automatically sold by the Reporting Person to satisfy tax withholding obligations in connection with the vesting of restricted stock units granted to the Reporting Person on December 4, 2024. The automatic sale of the Reporting Person's shares is provided for in a restricted stock unit agreement constituting a "binding contract" consistent with the affirmative defense to liability under Rule 10b5-1 and the sale does not represent a discretionary trade by the Reporting Person.

4. Includes 74,514 unvested RSUs.

	/s/ Ron Caponigro, Attorney-in-Fact	09/08/2025
	** 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.

FAQ

Why did Johanna Friedl-Naderer sell Dyne Therapeutics (DYN) shares on 09/04/2025 and 09/05/2025?

The Form 4 states the sales were automatic transactions to satisfy tax withholding obligations arising from the vesting of restricted stock units granted on September 3, 2024 and December 4, 2024.

How many shares did the reporting person sell and at what prices?

She sold 894 shares on 09/04/2025 at a weighted average price of $13.27 (range $13.08–$13.50) and 144 shares on 09/05/2025 at $13.41.

What was the reporting person's beneficial ownership after these transactions?

Following the reported sales, beneficial ownership was 94,873 shares, down from 95,017 shares prior to the 09/05/2025 transaction.

Were the trades discretionary or part of a pre-arranged plan?

The filing explains the sales were provided for in a restricted stock unit agreement constituting a binding contract consistent with the affirmative defense under Rule 10b5-1, and did not represent discretionary trades.

How many unvested RSUs remain for the reporting person?

The Form 4 discloses 74,514 unvested RSUs included in the reported holdings.