X0508 4 2025-10-22 0 0001599901 Avidity Biosciences, Inc. RNA 0001747528 Hughes Steven George C/O AVIDITY BIOSCIENCES, INC. 3020 CALLAN RD. SAN DIEGO CA 92121 0 1 0 0 Chief Medical Officer 1 Common Stock 2025-10-22 4 M 0 2209 10.16 A 41076 D Common Stock 2025-10-22 4 S 0 2209 47.5394 D 38867 D Stock Option (Right to Buy) 10.16 2025-10-22 4 M 0 2209 0 D 2034-01-19 Common Stock 2209 68458 D The exercises and sales reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan previously adopted by the Reporting Person on June 12, 2024. This represents a weighted-average price. These shares were sold in multiple transactions at prices ranging from $46.83 to $49.30. The Reporting Person undertakes to provide the Issuer, any securityholder 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. This option was granted on January 20, 2024 and vests in equal installments of 2,208 shares on each monthly anniversary of such grant date, until it is fully vested and exercisable on January 20, 2028. /s/ John B. Moriarty, Jr., J.D., Attorney-in-Fact 2025-10-24