144 0001636385 XXXXXXXX LIVE 0001649904 RHYTHM PHARMACEUTICALS INC 001-38223 222 Berkeley Street, 12th Floor BOSTON MA 02116 8572644280 HUNTER SMITH Officer Common Morgan Stanley Smith Barney LLC Executive Financial Services

1 New York Plaza 8th Floor New York NY 10004

28088 2648979.28 66420091 08/12/2025 NASDAQ Common 08/12/2025 Exercise of Stock Options Issuer N 28088 08/12/2025 Cash N 10b5-1 Sales for HUNTER SMITH

222 Berkeley Street, 12th Floor BOSTON MA 02116

Common 07/09/2025 42120 3389755.82 10b5-1 Sales for HUNTER SMITH

222 Berkeley Street, 12th Floor BOSTON MA 02116

Common 05/30/2025 23400 1437010.85 The securities to be sold were and will be received upon the exercise of stock options over the next three months. The dates of acquisition and payment were and will be the dates of exercise/sale. 08/12/2025 02/28/2025 /s/ Hunter Smith