# EDGAR Filing Document

**Accession Number:** 0001498428
**File Stem:** 0000950170-25-095929
**Filing Date:** 2025-7
**Character Count:** 7747
**Document Hash:** 59328accb1530814821a14f7a792e4b8
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0000950170-25-095929.hdr.sgml**: 20250715

**ACCESSION NUMBER**: 0000950170-25-095929

**CONFORMED SUBMISSION TYPE**: 4

**PUBLIC DOCUMENT COUNT**: 1

**CONFORMED PERIOD OF REPORT**: 20250714

**FILED AS OF DATE**: 20250715

**DATE AS OF CHANGE**: 20250715

**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** Cox John
- **CENTRAL INDEX KEY:** 0001498428

**ORGANIZATION NAME:**

**FILING VALUES:**
- **FORM TYPE:** 4
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-39509
- **FILM NUMBER:** 251125532

**MAIL ADDRESS:**
- **STREET 1:** C/O BIOVERATIV INC.
- **STREET 2:** 225 SECOND AVENUE
- **CITY:** WALTHAM
- **STATE:** MA
- **ZIP:** 02451
**ISSUER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Dyne Therapeutics, Inc.
- **CENTRAL INDEX KEY:** 0001818794
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 364883909
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**BUSINESS ADDRESS:**
- **STREET 1:** 1560 TRAPELO ROAD
- **CITY:** WALTHAM
- **STATE:** MA
- **ZIP:** 02451
- **BUSINESS PHONE:** (781) 786-8230

**MAIL ADDRESS:**
- **STREET 1:** 1560 TRAPELO ROAD
- **CITY:** WALTHAM
- **STATE:** MA
- **ZIP:** 02451

### UNITED STATES SECURITIES AND EXCHANGE COMMISSION
**Washington, D.C. 20549**

## FORM 4

### STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

[ ] 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**<sup>*</sup><br>Cox John<br><sub>(Last) (First) (Middle)</sub><br>C/O DYNE THERAPEUTICS, INC.<br>1560 TRAPELO ROAD<br><sub>(Street)</sub><br>WALTHAM, MA 02451<br><sub>(City) (State) (Zip)</sub> | **3. Date of Earliest Transaction (Month/Day/Year)**<br>2025-07-14 | **5. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[X] Director [ ] 10% Owner<br>[X] Officer (give title below) [ ] Other (specify below)<br>_CEO & President_ |
| **2. Issuer Name and Ticker or Trading Symbol**<br>Dyne Therapeutics, Inc. [ DYN ] | **4. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[X] Form filed by One Reporting Person<br>[ ] Form filed by More than One Reporting Person |

---

## Table I - Non-Derivative Securities

---

|  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Security | 2. Transaction Date | 2A. Deemed Execution Date | 3. Transaction Code (V) | 3. Transaction Code (V) | 4. Securities Acquired (A) or Disposed of (D) | 4. Securities Acquired (A) or Disposed of (D) | 4. Securities Acquired (A) or Disposed of (D) | 5. Amount of Securities Beneficially Owned | 6. Ownership Form | 7. Nature of Indirect Beneficial Ownership |
| 1. Title of Security | 2. Transaction Date | 2A. Deemed Execution Date | Code | V | Amount | (A) or (D) | Price | 5. Amount of Securities Beneficially Owned | 6. Ownership Form | 7. Nature of Indirect Beneficial Ownership |
| Common Stock | 2025-07-14 |  | P<sup>(1)</sup> |  | 100000 | A | 9.11<sup>(2)</sup> | 242179 | D |  |
| Common Stock | 2025-07-15 |  | G |  | 10000<sup>(3)</sup> | D | $0 | 232179 | D |  |
| Common Stock |  |  |  |  |  |  |  | 18000<sup>(3)</sup> | I | By Trust #1<sup>(4)</sup> |
| Common Stock | 2025-07-15 |  | G |  | 10000<sup>(3)</sup> | D | $0 | 222179 | D |  |
| Common Stock |  |  |  |  |  |  |  | 18000<sup>(3)</sup> | I | By Trust #2<sup>(4)</sup> |
| Common Stock | 2025-07-15 |  | G |  | 10000<sup>(3)</sup> | D | $0 | 212179 | D |  |
| Common Stock |  |  |  |  |  |  |  | 18000<sup>(3)</sup> | I | By Trust #3<sup>(4)</sup> |
| Common Stock | 2025-07-15 |  | G |  | 10000<sup>(3)</sup> | D | $0 | 202179<sup>(5)</sup> | D |  |
| Common Stock |  |  |  |  |  |  |  | 18000<sup>(3)</sup> | I | By Trust #4<sup>(4)</sup> |

---

## Table II - Derivative Securities

---

|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Derivative Security | 2. Conversion or Exercise Price | 3. Transaction Date | 3A. Deemed Execution Date | 4. Transaction Code (V) | 4. Transaction Code (V) | 5. Number of Derivative Securities Acquired (A) or Disposed of (D) | 5. Number of Derivative Securities Acquired (A) or Disposed of (D) | 6. Date Exercisable and Expiration Date | 6. Date Exercisable and Expiration Date | 7. Title and Amount of Underlying Securities | 7. Title and Amount of Underlying Securities | 8. Price of Derivative Security | 9. Number of Derivative Securities Beneficially Owned | 10. Ownership Form | 11. Nature of Indirect Beneficial Ownership |
| 1. Title of Derivative Security | 2. Conversion or Exercise Price | 3. Transaction Date | 3A. Deemed Execution Date | Code | V | (A) | (D) | Date Exercisable | Expiration Date | Title | Amount or Number of Shares | 8. Price of Derivative Security | 9. Number of Derivative Securities Beneficially Owned | 10. Ownership Form | 11. Nature of Indirect Beneficial Ownership |
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

---

### Footnotes:

(1) The Reporting Person's purchase of shares of Common Stock reported herein was matchable under Section 16(b) of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), to the extent of 8,121 shares, with the Reporting Person's sale of 4,061 shares on March 5, 2025 and 4,060 shares on June 5, 2025 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 Reporting Person has paid to the Issuer an aggregate amount of $29,017.22, representing the amount of the profit deemed realized in connection with the short-swing transaction under Section 16(b) of the Exchange Act.

(2) The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices within the range of $9.02 to $9.15, 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) This transaction represents a gift by the Reporting Person to a trust established for the benefit of a child of the Reporting Person.

(4) These shares of Common Stock are held in a trust for the benefit of a child of the Reporting Person.

(5) Includes 127,138 unvested RSUs.

**Signature:** /s/ Ron Caponigro, Attorney-in-Fact  
**Date:** 2025-07-15

### Remarks:

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.**