| Name | Relationship | Address | Signature | Signature date | CIK |
|---|---|---|---|---|---|
| Cox John | CEO & President, Director | C/O DYNE THERAPEUTICS, INC., 1560 TRAPELO ROAD, WALTHAM | /s/ Ron Caponigro, Attorney-in-Fact | 15 Jul 2025 | 0001498428 |
| Type | Sym | Class | Transaction | Value $ | Shares | Change % | * Price $ | Shares After | Date | Ownership | Footnotes |
|---|---|---|---|---|---|---|---|---|---|---|---|
| transaction | DYN | Common Stock | Purchase | $911,000 | +100,000 | +70% | $9.11 | 242,179 | 14 Jul 2025 | Direct | F1, F2 |
| transaction | DYN | Common Stock | Gift | $0 | -10,000 | -4.1% | $0.000000 | 232,179 | 15 Jul 2025 | Direct | F3 |
| transaction | DYN | Common Stock | Gift | $0 | -10,000 | -4.3% | $0.000000 | 222,179 | 15 Jul 2025 | Direct | F3 |
| transaction | DYN | Common Stock | Gift | $0 | -10,000 | -4.5% | $0.000000 | 212,179 | 15 Jul 2025 | Direct | F3 |
| transaction | DYN | Common Stock | Gift | $0 | -10,000 | -4.7% | $0.000000 | 202,179 | 15 Jul 2025 | Direct | F3, F5 |
| holding | DYN | Common Stock | 18,000 | 14 Jul 2025 | By Trust #1 | F3, F4 | |||||
| holding | DYN | Common Stock | 18,000 | 14 Jul 2025 | By Trust #2 | F3, F4 | |||||
| holding | DYN | Common Stock | 18,000 | 14 Jul 2025 | By Trust #3 | F3, F4 | |||||
| holding | DYN | Common Stock | 18,000 | 14 Jul 2025 | By Trust #4 | F3, F4 |
| Id | Content |
|---|---|
| F1 | 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. |
| F2 | 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. |
| F3 | This transaction represents a gift by the Reporting Person to a trust established for the benefit of a child of the Reporting Person. |
| F4 | These shares of Common Stock are held in a trust for the benefit of a child of the Reporting Person. |
| F5 | Includes 127,138 unvested RSUs. |