Dyne Therapeutics CMO sells 887 shares for taxes

Dyne Therapeutics, Inc. Chief Medical Officer Douglas Kerr reported an automatic sale of 887 shares of common stock at a weighted average price of $18.33 per share.

Rhea-AI Filing Summary

Dyne Therapeutics, Inc. Chief Medical Officer Douglas Kerr reported an automatic sale of 887 shares of common stock at a weighted average price of $18.33 per share. The shares were sold to satisfy tax withholding obligations tied to the vesting of restricted stock units granted on December 4, 2024, under a binding contract consistent with the Rule 10b5-1 affirmative defense. After this transaction, he holds 169,155 shares, including 145,313 unvested restricted stock units.

Insider Trade Summary 10b5-1

Net Seller: 887 shares

Net Sell 1 txn

Insider Kerr Douglas

Role Chief Medical Officer

Sold 887 shs ($16K)

Type	Security	Shares	Price	Value
Sale	Common Stock	887	$18.33	$16K

Holdings After Transaction: Common Stock — 169,155 shares (Direct)

Footnotes (3)

1. F1. 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.
2. F2. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $18.00 to $18.70, 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. F3. Includes 145,313 unvested RSUs.

Key Figures

Shares sold: 887 shares Weighted average sale price: $18.33 per share Post-transaction holdings: 169,155 shares +2 more

5 metrics

Shares sold 887 shares Automatic sale on June 16, 2026 to satisfy tax withholding

Weighted average sale price $18.33 per share Common stock sale associated with RSU vesting

Post-transaction holdings 169,155 shares Common stock held by Douglas Kerr after the sale

Unvested RSUs included 145,313 RSUs Unvested restricted stock units within total holdings

Sale price range $18.00–$18.70 per share Multiple transactions underlying the weighted average price

Key Terms

restricted stock units, Rule 10b5-1, weighted average price, tax withholding obligations

4 terms

restricted stock units financial

"Represents shares automatically sold ... in connection with the vesting of restricted stock units granted to the Reporting Person on December 4, 2024."

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

Rule 10b5-1 regulatory

"provided for in a restricted stock unit agreement constituting a "binding contract" consistent with the affirmative defense to liability under Rule 10b5-1"

Rule 10b5-1 is a regulation that allows company insiders to buy or sell their shares at predetermined times, even if they have access to non-public information. It acts like setting a schedule in advance for transactions, helping prevent accusations of unfair trading. This rule provides a way for insiders to plan trades transparently, giving investors confidence that these transactions are not based on hidden information.

weighted average price financial

"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $18.00 to $18.70"

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.

tax withholding obligations financial

"shares automatically sold ... to satisfy tax withholding obligations in connection with the vesting of restricted stock units"

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What insider transaction did Dyne Therapeutics (DYN) report for Douglas Kerr?

Dyne Therapeutics reported that Chief Medical Officer Douglas Kerr automatically sold 887 common shares. The sale covered tax withholding obligations from vesting restricted stock units granted on December 4, 2024, rather than a discretionary open-market trade.

At what price were Douglas Kerr’s Dyne Therapeutics (DYN) shares sold?

The reported weighted average sale price was $18.33 per Dyne Therapeutics share. Footnotes explain the 887 shares were sold in multiple trades within a price range from $18.00 to $18.70 per share.

Why were Dyne Therapeutics (DYN) shares sold by the CMO on this Form 4?

The shares were sold automatically to satisfy tax withholding obligations from vesting restricted stock units. A restricted stock unit agreement provided for the sale as a binding contract consistent with the Rule 10b5-1 affirmative defense, indicating it was not a discretionary trade.

How many Dyne Therapeutics (DYN) shares does Douglas Kerr hold after the sale?

Following the reported transaction, Douglas Kerr holds 169,155 Dyne Therapeutics common shares. This total includes 145,313 unvested restricted stock units that remain subject to vesting conditions under the company’s equity compensation arrangements.

Was Douglas Kerr’s Dyne Therapeutics (DYN) share sale under a Rule 10b5-1 plan?

The filing states the automatic sale is provided for in a restricted stock unit agreement constituting a binding contract consistent with the affirmative defense under Rule 10b5-1. This indicates the sale was pre-arranged rather than a timing-based discretionary decision.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 06/17/2026 - 04:08 PM EDT 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^*

Kerr Douglas

(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)

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
06/16/2026

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	06/16/2026		S(1)		887	D	$18.33(2)	169,155(3)	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 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.

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 $18.00 to $18.70, 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. Includes 145,313 unvested RSUs.

	/s/ Ron Caponigro, Attorney-in-Fact	06/17/2026
	** 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)