Dyne Therapeutics CFO sells 1,797 shares at $26

Dyne Therapeutics, Inc. officer Erick Lucera (Chief Financial Officer) reported selling 1,797 shares of common stock on August 13, 2026 at a weighted average price of $26.28 per share.

Rhea-AI Filing Summary

Dyne Therapeutics, Inc. officer Erick Lucera (Chief Financial Officer) reported selling 1,797 shares of common stock on August 13, 2026 at a weighted average price of $26.28 per share. The sale was an automatic disposition to satisfy tax withholding obligations upon vesting of restricted stock units under a pre-existing agreement treated as a Rule 10b5-1 binding contract, and is described as not a discretionary trade. Following this transaction, Lucera directly holds 119,766 shares, including 106,451 unvested RSUs.

Insider Trade Summary 10b5-1

Net Seller: 1,797 shares

Net Sell 1 txn

Insider Lucera Erick

Role Chief Financial Officer

Sold 1,797 shs ($47K)

Type	Security	Shares	Price	Value
Sale	Common Stock F1, F2, F3	1,797	$26.28	$47K

Holdings After Transaction: Common Stock — 119,766 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 February 12, 2026. 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 $26.17 to $26.39, 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 106,451 unvested RSUs.

Key Figures

Shares sold: 1,797 shares Weighted average sale price: $26.28 per share Sale price range: $26.17–$26.39 per share +2 more

5 metrics

Shares sold 1,797 shares Common stock sold by CFO on August 13, 2026

Weighted average sale price $26.28 per share Average price for 1,797 shares sold on August 13, 2026

Sale price range $26.17–$26.39 per share Range of prices for multiple transactions included in the sale

Shares held after transaction 119,766 shares Direct holdings of CFO following the sale

Unvested RSUs included in holdings 106,451 RSUs Unvested restricted stock units included in post-transaction total

Key Terms

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

4 terms

restricted stock units financial

"vesting of restricted stock units granted to the Reporting Person"

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

"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"

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

"sold by the Reporting Person to satisfy tax withholding obligations in connection with the vesting"

FAQ

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

What insider transaction did Dyne Therapeutics (DYN) CFO Erick Lucera report?

Erick Lucera reported a sale of 1,797 Dyne Therapeutics (DYN) common shares on August 13, 2026 at a weighted average price of $26.28 per share, conducted in connection with tax withholding on vested restricted stock units.

Was the DYN CFO’s August 13, 2026 share sale a discretionary trade?

The filing states the sale was not a discretionary trade. Shares were automatically sold to satisfy tax withholding obligations under a restricted stock unit agreement that constitutes a Rule 10b5-1 binding contract.

How many Dyne Therapeutics (DYN) shares does the CFO hold after this transaction?

After the reported sale, Erick Lucera directly holds 119,766 shares of Dyne Therapeutics common stock. This total includes 106,451 unvested restricted stock units (RSUs), as disclosed in the footnotes to the Form 4 filing.

At what prices were the DYN shares sold in the CFO’s August 2026 transaction?

The reported price is a weighted average of $26.28 per share. The 1,797 shares were sold in multiple transactions at prices ranging from $26.17 to $26.39, inclusive, according to the Form 4 footnote.

Why did Dyne Therapeutics (DYN) CFO sell 1,797 shares on August 13, 2026?

The sale of 1,797 shares was made to satisfy tax withholding obligations triggered by the vesting of restricted stock units granted on February 12, 2026. The transaction was executed automatically under a Rule 10b5-1 compliant agreement.

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

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

Lucera Erick

(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 Financial Officer

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
08/13/2026

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	08/13/2026		S(1)		1,797	D	$26.28(2)	119,766(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 February 12, 2026. 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 $26.17 to $26.39, 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 106,451 unvested RSUs.

	/s/ Dan Wilson, Attorney-in-Fact	08/17/2026
	** 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)