X0609 4 2026-10-15 0001984086 Septerna, Inc. SEPN 0001748622 Bhatt Elizabeth false C/O SEPTERNA, INC. 250 EAST GRAND AVENUE SOUTH SAN FRANCISCO CA 94080 false true false false President and COO true Common Stock 2026-10-15 4 M false 4000 6.81 A 178209 D Common Stock 2026-10-15 4 S false 1094 36.8715 D 177115 D Common Stock 2026-10-15 4 S false 2906 37.6142 D 174209 D Stock Option (Right to Buy) 6.81 2026-10-15 4 M false 4000 0 D 2034-09-22 Common Stock 4000 58230 D This transaction was effected pursuant to a Rule 10b5-1 sales plan adopted by the Reporting Person on October 20, 2025. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $36.24 to $37.23. The Reporting Person undertakes to provide to the Issuer, any security holder 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. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $37.31 to $38.07. The Reporting Person undertakes to provide to the Issuer, any security holder 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. 1/48th of the shares subject to such option vest and become exercisable in substantially equal monthly installments on each monthly anniversary of October 28, 2024, subject to the Reporting Person's continuous service to the Issuer on each such date. /s/ Mark A. Wilson, Attorney-in-Fact 2026-10-19