Dyne Therapeutics (DYN) CEO John Cox granted large RSU and option awards

Rhea-AI Filing Summary

Dyne Therapeutics CEO and President John Cox reported new equity awards in the company’s stock. On February 12, 2026, he received 180,000 shares of common stock in the form of restricted stock units that vest quarterly over four years starting May 12, 2026.

He was also granted a stock option for 285,000 shares of common stock at an exercise price of $16 per share, vesting in equal monthly installments over four years through February 12, 2030. Following these awards, he directly beneficially owns 376,877 shares of common stock, which include unvested RSUs.

Additional holdings of 18,000 shares of common stock in each of four separate trusts are reported as indirect ownership, with each trust held for the benefit of a child of the reporting person.

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

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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^*

Cox John

(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)

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

3. Date of Earliest Transaction (Month/Day/Year)
02/12/2026

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	02/12/2026		A		180,000(1)	A	$0	376,877(2)	D
Common Stock								18,000	I	By Trust #1(3)
Common Stock								18,000	I	By Trust #2(3)
Common Stock								18,000	I	By Trust #3(3)
Common Stock								18,000	I	By Trust #4(3)

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)	$16	02/12/2026		A		285,000		(4)	02/11/2036	Common Stock	285,000	$0	285,000	D

Explanation of Responses:

1. Consists of shares of Common Stock issuable under 180,000 restricted stock units ("RSUs"). Each RSU represents the right to receive one share of Common Stock upon vesting. These RSUs are scheduled to vest in equal quarterly installments over four years with the first installment vesting on May 12, 2026.

2. Includes 288,976 unvested RSUs.

3. These shares are held in a trust for the benefit of a child of the Reporting Person.

4. This option was granted on February 12, 2026. The shares underlying the option are scheduled to vest over four years in equal monthly installments through February 12, 2030.

	/s/ Ron Caponigro, Attorney-in-Fact	02/17/2026
	** 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).
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FAQ

What did Dyne Therapeutics (DYN) CEO John Cox report in this Form 4?

John Cox reported new equity awards from Dyne Therapeutics. He received 180,000 restricted stock units and a stock option for 285,000 shares, both granted on February 12, 2026, significantly increasing his reported beneficial ownership position in the company’s common stock.

How many Dyne Therapeutics (DYN) RSUs were granted to John Cox and how do they vest?

John Cox received 180,000 restricted stock units from Dyne Therapeutics. Each RSU represents one share of common stock and is scheduled to vest in equal quarterly installments over four years, with the first installment vesting on May 12, 2026, subject to continued service conditions.

What are the key terms of John Cox’s Dyne Therapeutics stock option grant?

John Cox was granted a stock option to purchase 285,000 shares of Dyne Therapeutics common stock at an exercise price of $16. The option vests in equal monthly installments over four years and is scheduled to fully vest by February 12, 2030, assuming applicable conditions are met.

How many Dyne Therapeutics shares does John Cox beneficially own after these transactions?

After the reported grants, John Cox beneficially owns 376,877 shares of Dyne Therapeutics common stock directly. This total includes 288,976 unvested restricted stock units, indicating a substantial portion of his position is subject to future vesting over time.

What indirect Dyne Therapeutics (DYN) holdings related to John Cox are disclosed?

The filing discloses four indirect positions of 18,000 Dyne Therapeutics shares each. These shares are held by separate trusts, described as being for the benefit of a child of John Cox, and are reported as indirect beneficial ownership associated with those trusts.

When do John Cox’s new Dyne Therapeutics equity awards start and finish vesting?

The 180,000 RSUs begin vesting on May 12, 2026, in equal quarterly installments over four years. The 285,000-share stock option vests in equal monthly installments and is scheduled to complete vesting by February 12, 2030, based on the grant terms.