X0306 4 2021-02-11 0 0001649904 RHYTHM PHARMACEUTICALS, INC. RYTM 0001801372 Chien Jennifer 222 BERKELEY STREET, 12TH FLOOR BOSTON MA 02116 0 1 0 0 EVP, Head of North America Restricted Stock Units 2021-02-11 4 A 0 8125 0 A Common Stock 8125 8125 D Stock Option (Right to Buy) 30.66 2021-02-11 4 A 0 48750 0 A 2031-02-10 Common Stock 48750 48750 D Each restricted stock unit represents a contingent right to receive one share of Issuer common stock. The restricted stock units vest as to 25% of the total shares on each of February 11, 2022, February 11, 2023, February 11, 2024 and February 11, 2025. The restricted stock units have no expiration date The stock options were granted on February 11, 2021. The options vest and become exercisable in 16 substantially equal installments upon the Reporting Person's completion of each three full months of successive service to the Issuer following the grant date. /s/ Hunter Smith, attorney-in-fact for Jennifer Chien 2021-02-16