144 0002040363 XXXXXXXX LIVE 0001984086 Septerna, Inc. 001-42382 250 East Grand Avenue South San Francisco CA 94080 650-338-3533 SAMIRA SHAIKHLY Officer Common Morgan Stanley Smith Barney LLC Executive Financial Services

1 New York Plaza 8th Floor New York NY 10004

8428 286804.84 45075533 06/12/2026 NASDAQ Common 06/12/2026 Exercise of Stock Options Issuer N 8428 06/12/2026 Cash N 10b5-1 Sales for SAMIRA SHAIKHLY

250 East Grand Avenue South San Francisco CA 94080

Common 06/01/2026 5935 171682.78 10b5-1 Sales for SAMIRA SHAIKHLY

250 East Grand Avenue South San Francisco CA 94080

Common 05/26/2026 11798 354656.37 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. 06/12/2026 10/31/2025 /s/ Samira Shaikhly