Director at Dyne Therapeutics (DYN) receives grant of 35,152 stock options

Rhea-AI Filing Summary

Dyne Therapeutics director Catherine Stehman-Breen received a new stock option grant as part of her compensation. On June 5, 2026 she was awarded options to purchase 35,152 shares of Dyne Therapeutics common stock at an exercise price of $17.04 per share.

The option vests in full on the earlier of June 5, 2027 or the company’s 2027 Annual Meeting of Stockholders, as long as she continues to serve. Following this grant, she holds 35,152 stock options directly under this award, which expire on June 4, 2036.

Insider Trade Summary

1 transaction reported

Mixed 1 txn

Insider Stehman-Breen Catherine

Role null

Type	Security	Shares	Price	Value
Grant/Award	Stock option (right to buy)	35,152	$0.00	--

Holdings After Transaction: Stock option (right to buy) — 35,152 shares (Direct, null)

Footnotes (1)

1. [object Object]

Key Figures

Option grant size: 35,152 options Exercise price: $17.04 per share Underlying shares: 35,152 shares +2 more

5 metrics

Option grant size 35,152 options Stock option grant on June 5, 2026

Exercise price $17.04 per share Conversion or exercise price of options

Underlying shares 35,152 shares Common stock underlying the option grant

Post-grant option holdings 35,152 options Total options following transaction under this award

Option expiration date June 4, 2036 Expiration of granted stock options

Key Terms

Stock option (right to buy), exercise price, vest in full, Annual Meeting of Stockholders, +1 more

5 terms

Stock option (right to buy) financial

"security_title: Stock option (right to buy)"

exercise price financial

"conversion_or_exercise_price: 17.0400"

The exercise price is the fixed amount at which you can buy or sell an asset, like a stock, when using an options contract. It matters because it helps determine whether exercising the option will be profitable or not, depending on the current market price. Think of it as the set price you agree on today to buy or sell later.

vest in full financial

"The shares underlying the option are scheduled to vest in full"

Annual Meeting of Stockholders financial

"the Issuer's 2027 Annual Meeting of Stockholders"

expiration date financial

"expiration_date: 2036-06-04T00:00:00.000Z"

The expiration date is the deadline after which a financial contract, such as an option or a futures agreement, is no longer valid or can be exercised. It matters to investors because it determines the timeframe during which they can take action or benefit from the contract, similar to how a coupon or a food item has a limited period of usefulness. Once the expiration date passes, the contract loses its value or ability to be used.

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Form 4 Insider Transactions: What Each Field Means →

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).

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^*

Stehman-Breen Catherine

(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)

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
06/05/2026

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

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
Stock option (right to buy)	$17.04	06/05/2026		A		35,152		(1)	06/04/2036	Common Stock	35,152	$0.00	35,152	D

Explanation of Responses:

1. This option was granted on June 5, 2026. The shares underlying the option are scheduled to vest in full on the earlier of (i) June 5, 2027 or (ii) the date of the Issuer's 2027 Annual Meeting of Stockholders, subject to continued service.

	/s/ Ron Caponigro, Attorney-in-Fact	06/09/2026
	** 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)

FAQ

What insider transaction did Dyne Therapeutics (DYN) report for Catherine Stehman-Breen?

Dyne Therapeutics reported that director Catherine Stehman-Breen received a stock option grant for 35,152 shares. These options give her the right to buy common stock at a fixed price, reflecting routine equity-based director compensation at the company.

How many Dyne Therapeutics (DYN) options were granted and at what exercise price?

Stehman-Breen was granted options on 35,152 underlying shares of Dyne Therapeutics common stock at an exercise price of $17.04 per share. This fixed price is what she must pay per share if she chooses to exercise the options.

When do Catherine Stehman-Breen’s Dyne Therapeutics (DYN) stock options vest?

The options are scheduled to vest in full on the earlier of June 5, 2027 or the date of Dyne Therapeutics’ 2027 Annual Meeting of Stockholders. Vesting is conditioned on her continued service with the company until that vesting date.

When do the newly granted Dyne Therapeutics (DYN) options to Stehman-Breen expire?

The stock options granted to Stehman-Breen expire on June 4, 2036. After this expiration date she can no longer exercise them, so the long term of the option provides an extended window to choose when to purchase shares.

Is the Dyne Therapeutics (DYN) Form 4 transaction a purchase or a compensation award?

The Form 4 shows a compensation-related grant, coded as an “A” transaction for a grant or award acquisition. It is not an open-market stock purchase; instead it reflects the company awarding stock options as part of director compensation.