X0508 4 2025-11-10 0001984086 Septerna, Inc. SEPN 0002040349 Long Daniel D. C/O SEPTERNA, INC. 250 EAST GRAND AVENUE SOUTH SAN FRANCISCO CA 94080 false true false false SVP, Drug Discovery false Common Stock 2025-11-10 4 S false 3501 18.0586 D 92911 D The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $18.04 to $18.16. 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. Includes 3,501 shares acquired under the Septerna, Inc. 2024 Employee Stock Purchase Plan on October 31, 2025 in transactions that were exempt under Rule 16b-3(c). /s/ Ran Xiao, Attorney-in-Fact 2025-11-13