X0609 4 2026-08-13 0001649904 RHYTHM PHARMACEUTICALS, INC. RYTM 0001801372 Lee Jennifer Kayden false C/O RHYTHM PHARMACEUTICALS, INC. 222 BERKELEY STREET, 12TH FLOOR BOSTON MA 02116 1 EVP, Head of North America 1 Common Stock 2026-08-13 4 M 0 35000 24.29 A 54233 D Common Stock 2026-08-13 4 M 0 21601 6.80 A 75834 D Common Stock 2026-08-13 4 S 0 75834 117.3818 D 0 D Stock Options (Right to Buy) 24.29 2026-08-13 4 M 0 35000 0 D 2030-11-09 Common Stock 35000 36283 D Stock Options (Right to Buy) 6.80 2026-08-13 4 M 0 21601 0 D 2032-02-08 Common Stock 21601 0 D The exercises and sales reported in the Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 14, 2026. The stock options were granted on November 9, 2020. 25% of the shares subject to the option vested and become exercisable on November 9, 2021 and the remaining 75% of the shares subject to the option vested and become exercisable in 12 substantially equal installments upon the Reporting Person's completion of each three full months of successive service to the Issuer thereafter. The stock options were granted on February 9, 2022. The options vested and became 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/ Stephen Vander Stoep, attorney-in-fact for Jennifer Kayden Lee 2026-08-14