X0206 3 2020-09-16 0 0001818794 Dyne Therapeutics, Inc. DYN 0001824673 McNeill Jonathan C/O DYNE THERAPEUTICS, INC. 830 WINTER STREET WALTHAM MA 02451 0 1 0 0 See Remarks Common Stock 19898 D Stock Option (right to buy) 0.73 2029-02-25 Common Stock 78528 D Stock Option (right to buy) 5.54 2030-07-30 Common Stock 33469 D Stock Option (right to buy) 5.54 2030-07-30 Common Stock 64999 D The option was granted on February 26, 2019 for 98,426 shares. The shares underlying the option vest over four years, with 25% of the original number of shares vested on February 1, 2020 and the remaining shares vesting in equal quarterly installments thereafter. The option was granted on July 31, 2020. The shares underlying the option vest over four years in equal quarterly installments through July 31, 2024. The option was granted on July 31, 2020. The shares underlying the option vest over four years in equal quarterly installments through July 31, 2024. Vice President, Business Development Exhibit Index: 24.1 Power of Attorney /s/ Richard Scalzo, Attorney-in-Fact 2020-09-16