STOCK TITAN

Dyne Therapeutics (NASDAQ: DYN) CEO logs automatic RSU tax sale

Filing Impact
(Neutral)
Filing Sentiment
(Negative)
Form Type
4

Rhea-AI Filing Summary

Dyne Therapeutics, Inc. CEO and President John Cox reported an automatic sale of 2,683 shares of common stock on June 16, 2026 at a weighted average price of $18.33 per share. According to the disclosure, the shares were sold to satisfy tax withholding obligations related to the vesting of restricted stock units granted on December 4, 2024, under a binding contract consistent with the Rule 10b5-1 affirmative defense, meaning the sale was not a discretionary trade. Following this transaction, Cox directly holds 368,151 shares, including 259,564 unvested RSUs, and indirectly holds 18,000 shares in each of four trusts for the benefit of a child.

Positive

  • None.

Negative

  • None.
Insider Cox John
Role CEO & President
Sold 2,683 shs ($49K)
Type Security Shares Price Value
Sale Common Stock 2,683 $18.33 $49K
holding Common Stock -- -- --
holding Common Stock -- -- --
holding Common Stock -- -- --
holding Common Stock -- -- --
Holdings After Transaction: Common Stock — 368,151 shares (Direct, null); Common Stock — 18,000 shares (Indirect, By Trust #1)
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 December 4, 2024. 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 $18.00 to $18.70, 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 259,564 unvested RSUs. These shares are held in a trust for the benefit of a child of the Reporting Person.
Shares sold 2,683 shares Automatic sale on June 16, 2026
Weighted average sale price $18.33 per share Open-market sale range $18.00–$18.70
Direct holdings after transaction 368,151 shares Common stock held directly by CEO after sale
Unvested RSUs included 259,564 RSUs Unvested restricted stock units within direct holdings
Trust holdings per trust 18,000 shares Common stock held indirectly in each of four trusts
restricted stock units financial
"vesting of restricted stock units granted to the Reporting Person on December 4, 2024"
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.
tax withholding obligations financial
"shares automatically sold by the Reporting Person to satisfy tax withholding obligations"
Rule 10b5-1 regulatory
"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.
unvested RSUs financial
"Includes 259,564 unvested RSUs."
See more from StockTitan in Google Search and AI answers. Adds StockTitan as a preferred source · opens Google
Add on Google
Learn about SEC filing dates
SEC Form 4
FORM 4UNITED 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*
Cox John

(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)
XDirector10% Owner
XOfficer (give title below)Other (specify below)
CEO & President
2a. Foreign Trading Symbol
3. Date of Earliest Transaction (Month/Day/Year)
06/16/2026
6. Individual or Joint/Group Filing (Check Applicable Line)
XForm 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)
CodeVAmount(A) or (D)Price
Common Stock06/16/2026S(1)2,683D$18.33(2)368,151(3)D
Common Stock18,000IBy Trust #1(4)
Common Stock18,000IBy Trust #2(4)
Common Stock18,000IBy Trust #3(4)
Common Stock18,000IBy Trust #4(4)
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)
CodeV(A)(D)Date ExercisableExpiration DateTitleAmount 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 December 4, 2024. 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 $18.00 to $18.70, 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 259,564 unvested RSUs.
4. These shares are held in a trust for the benefit of a child of the Reporting Person.
/s/ Ron Caponigro, Attorney-in-Fact06/17/2026
** Signature of Reporting PersonDate
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 CEO John Cox?

Dyne Therapeutics reported that CEO John Cox automatically sold 2,683 shares of common stock. The sale occurred on June 16, 2026 at a weighted average price of $18.33 per share to cover tax withholding obligations tied to vested restricted stock units.

Was the Dyne Therapeutics (DYN) CEO’s 2,683-share sale a discretionary trade?

No, the 2,683-share sale was not discretionary. The filing states the shares were automatically sold to satisfy tax withholding on RSU vesting under a binding contract consistent with the Rule 10b5-1 affirmative defense, meaning the timing was pre-arranged.

How many Dyne Therapeutics (DYN) shares does CEO John Cox hold after the reported sale?

After the reported sale, John Cox directly holds 368,151 Dyne Therapeutics common shares. This total includes 259,564 unvested restricted stock units, and he also has indirect ownership of 18,000 shares in each of four trusts for the benefit of a child.

At what price were the Dyne Therapeutics (DYN) shares sold in the CEO’s Form 4 filing?

The reported sale used a weighted average price of $18.33 per share. The filing notes the shares were sold in multiple transactions at prices ranging from $18.00 to $18.70, and detailed trade breakdowns are available upon request from the issuer or regulators.

What is the role of restricted stock units in the Dyne Therapeutics (DYN) CEO’s transaction?

The sale was triggered by the vesting of restricted stock units granted on December 4, 2024. Shares were automatically sold to cover tax withholding obligations from that vesting, and the CEO’s remaining direct holdings include 259,564 unvested RSUs as part of his equity compensation.

How are trust holdings described in the Dyne Therapeutics (DYN) CEO Form 4?

The Form 4 lists four indirect holdings of 18,000 Dyne Therapeutics shares each, identified as Trust #1 through Trust #4. A footnote explains these shares are held in a trust for the benefit of a child of the reporting person, indicating estate or family planning structures.