Dyne director buys shares, receives option grant

Dyne Therapeutics director Brian S. Posner reported two insider transactions.

Rhea-AI Filing Summary

Dyne Therapeutics director Brian S. Posner reported two insider transactions. He made an open-market purchase of 2,000 shares of common stock at $16.94 per share, bringing his directly held stake to 24,500 shares.

He also received a grant of stock options covering 35,152 shares of common stock with an exercise price of $17.04 per share. According to the disclosure, these options vest in full on the earlier of June 5, 2027 or the date of Dyne Therapeutics’ 2027 annual stockholders’ meeting, subject to his continued service.

Insider Trade Summary

Net Buyer: 2,000 shares

Net Buy 2 txns

Insider Posner Brian S

Role Director

Bought 2,000 shs ($34K)

Type	Security	Shares	Price	Value
Purchase	Common Stock	2,000	$16.94	$34K
Grant/Award	Stock option (right to buy)	35,152	$0.00	$0.00

Holdings After Transaction: Stock option (right to buy) — 35,152 contracts (Direct); Common Stock — 24,500 shares (Direct)

Footnotes (1)

1. F1. 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.

Key Figures

Open-market purchase: 2,000 shares at $16.94 Post-trade holdings: 24,500 shares Option grant size: 35,152 options +2 more

5 metrics

Open-market purchase 2,000 shares at $16.94 Common Stock purchase on June 8, 2026

Post-trade holdings 24,500 shares Common Stock directly owned after purchase

Option grant size 35,152 options Stock options granted June 5, 2026

Option exercise price $17.04 per share Stock option (right to buy) exercise price

Option vesting date June 5, 2027 Or earlier 2027 annual meeting, subject to service

Key Terms

open-market purchase, stock option (right to buy), exercise price, vest in full, +1 more

5 terms

open-market purchase financial

"He made an open-market purchase of 2,000 shares of common stock"

An open-market purchase is when an investor or a company buys shares on a public stock exchange at the going market price, rather than through a private deal. It matters to investors because these purchases change how many shares are available, can push the stock price up or signal confidence from large buyers, and often affect per-share metrics like earnings—think of it like someone buying lots of apples off a grocery shelf, reducing supply and potentially raising the price.

stock option (right to buy) financial

"Stock option (right to buy) with an exercise price of $17.04"

exercise price financial

"stock options covering 35,152 shares with an exercise price of $17.04"

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

"options vest in full on the earlier of June 5, 2027 or the 2027 meeting"

annual meeting of stockholders financial

"the Issuer's 2027 Annual Meeting of Stockholders, subject to continued service"

FAQ

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

What insider transactions did Dyne Therapeutics (DYN) director Brian Posner report?

Brian S. Posner reported buying 2,000 Dyne Therapeutics common shares in the open market and receiving a grant of 35,152 stock options. The options relate to common stock and form part of his compensation package as a director.

At what price did Brian Posner buy Dyne Therapeutics (DYN) shares on the open market?

He purchased 2,000 Dyne Therapeutics common shares at an average price of $16.94 per share. This open-market transaction increased his directly owned position, as disclosed in the Form 4 insider trading report.

How many Dyne Therapeutics (DYN) shares does Brian Posner own after these transactions?

After the open-market purchase, Brian S. Posner directly owns 24,500 shares of Dyne Therapeutics common stock. This figure excludes the separate stock options, which represent the right to acquire additional shares in the future at a set price.

What are the terms of Brian Posner’s Dyne Therapeutics (DYN) stock option grant?

He was granted stock options for 35,152 Dyne Therapeutics shares with a $17.04 exercise price. The options vest in full on the earlier of June 5, 2027, or the company’s 2027 annual stockholders’ meeting, subject to continued service.

When will Brian Posner’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 requires Brian S. Posner to maintain continued service through that time.

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

Form 4 Insider Transactions: What Each Field Means →

See more from StockTitan in Google Search and AI answers. Adds StockTitan as a preferred source · opens Google

Add on Google Not now

Accepted by SEC EDGAR 06/09/2026 - 05:06 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).

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^*

Posner Brian S

(Last) (First) (Middle)

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
Common Stock	06/08/2026		P		2,000	A	$16.94	24,500	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
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)