Dyne Therapeutics (DYN) CCO auto-sells shares to cover RSU taxes

Rhea-AI Filing Summary

Dyne Therapeutics, Inc. Chief Commercial Officer Johanna Friedl-Naderer reported an automatic sale of 228 shares of common stock on May 13, 2026 at a weighted average price of $18.36 per share. The shares were sold solely to cover tax withholding tied to the vesting of restricted stock units under a pre-arranged agreement treated as a binding contract consistent with Rule 10b5-1, meaning it was not a discretionary trade. After the transaction, she holds 154,353 shares in total, including 126,040 unvested restricted stock units.

Insights

Equity compensation and insider-transactions analyst

Small, pre-planned tax sale with limited informational value.

Dyne Therapeutics’ Chief Commercial Officer completed an automatic sale of 228 common shares at a weighted average of $18.36 on May 13, 2026. The filing states the sale was required to satisfy tax withholding from vesting restricted stock units granted on February 12, 2026.

The footnote explains this mechanism is set by a restricted stock unit agreement treated as a binding contract under Rule 10b5-1, so the timing is pre-arranged rather than discretionary. This distinguishes it from an open-market sale based on the insider’s short-term view.

After the sale, the officer still holds 154,353 shares, including 126,040 unvested RSUs. The number of shares sold is very small relative to this position, reinforcing that this is a routine tax-related transaction rather than a significant change in ownership.

Insider Trade Summary 10b5-1

Net Seller: 228 shares ($4,186)

Net Sell 1 txn

Insider Friedl-Naderer Johanna

Role Chief Commercial Officer

Sold 228 shs ($4K)

Type	Security	Shares	Price	Value
Sale	Common Stock	228	$18.36	$4K

Holdings After Transaction: Common Stock — 154,353 shares (Direct, null)

Footnotes (1)

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. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $18.20 to $18.41, 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. Includes 126,040 unvested RSUs.

Key Figures

Shares sold: 228 shares Average sale price: $18.36 per share Post-transaction holdings: 154,353 shares +3 more

6 metrics

Shares sold 228 shares Automatic sale on May 13, 2026

Average sale price $18.36 per share Weighted average price for 228 shares sold

Post-transaction holdings 154,353 shares Total shares held after sale

Unvested RSUs 126,040 units Unvested restricted stock units included in holdings

Sale price range $18.20–$18.41 Range of individual trade prices within transaction

Net shares sold 228 shares Net change from all reported transactions

Key Terms

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

3 terms

restricted stock units financial

"Represents shares automatically sold by the Reporting Person to satisfy tax withholding obligations in connection with the vesting of restricted stock units granted"

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"

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.

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).

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^*

Friedl-Naderer Johanna

(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 Commercial Officer

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
05/13/2026

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	05/13/2026		S(1)		228	D	$18.36(2)	154,353(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 $18.20 to $18.41, 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 126,040 unvested RSUs.

	/s/ Ron Caponigro, Attorney-in-Fact	05/14/2026
	** 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 did Dyne Therapeutics (DYN) disclose in this Form 4 filing?

Dyne Therapeutics reported that Chief Commercial Officer Johanna Friedl-Naderer automatically sold 228 shares of common stock. The sale was to pay tax withholding on recently vested restricted stock units under a pre-arranged agreement, not a discretionary open-market trade.

How many Dyne Therapeutics shares did the CCO sell and at what price?

The CCO sold 228 shares of Dyne Therapeutics common stock at a weighted average price of $18.36 per share. The filing notes individual trades occurred between $18.20 and $18.41, and detailed breakdowns are available on request from the company or regulators.

Why were Johanna Friedl-Naderer’s Dyne Therapeutics shares sold in this transaction?

The shares were sold automatically to cover tax withholding obligations tied to vesting restricted stock units granted on February 12, 2026. This mechanism is provided in her RSU agreement and is treated as a binding contract consistent with the affirmative defense under Rule 10b5-1.

How many Dyne Therapeutics shares does the CCO hold after this Form 4 transaction?

Following the sale, the Chief Commercial Officer holds 154,353 Dyne Therapeutics shares. This total includes 126,040 unvested restricted stock units, meaning most of her reported position remains in the form of time-based equity compensation that will vest in the future.

Was the Dyne Therapeutics CCO’s share sale discretionary or under a Rule 10b5-1 arrangement?

The filing describes the sale as automatic under a restricted stock unit agreement constituting a binding contract consistent with Rule 10b5-1. It explicitly states the transaction does not represent a discretionary trade by the reporting person, signaling a routine tax-related mechanism.