X0508 4 2023-11-15 0 0001818794 Dyne Therapeutics, Inc. DYN 0001824542 Beskrovnaya Oxana C/O DYNE THERAPEUTICS, INC. 1560 TRAPELO ROAD WALTHAM MA 02451 0 1 0 0 Chief Scientific Officer 0 Common Stock 2023-11-15 4 A 0 93718 0.00 A 178052 D Stock Option (right to buy) 10.88 2023-11-15 4 A 0 36495 0.00 A 2033-11-14 Common Stock 36495 36495 D Consists of shares of Common Stock issuable under 93,718 restricted stock units ("RSUs"). Each RSU represents the right to receive one share of Common Stock upon vesting. These RSUs are scheduled to vest in equal quarterly installments over four years with the first installment vesting on February 15, 2024. Includes 151,588 unvested RSUs. This option was granted on November 15, 2023. The shares underlying the option are scheduled to vest over four years in equal monthly installments through November 15, 2027. /s/ Richard Scalzo, Attorney-in-Fact 2023-11-16