SCHEDULE 13G/A

Septerna Inc

Common Stock, $0.001 par value per share · CUSIP: 81734D104

Event date: 2025-12-31

Reporting persons may disclose overlapping interests. Their amounts are shown individually and are not added into a filing total.

Filing-level shares

Unavailable

Percent of class

Unavailable

• BIOTECHNOLOGY VALUE FUND L P

  Shares: 919,814.00 · Class: 2.0%

• BVF I GP LLC

  Shares: 919,814.00 · Class: 2.0%

• BIOTECHNOLOGY VALUE FUND II LP

  Shares: 671,492.00 · Class: 1.5%

• BVF II GP LLC

  Shares: 671,492.00 · Class: 1.5%

• Biotechnology Value Trading Fund OS LP

  Shares: 104,119.00 · Class: 0.2%

• BVF Partners OS Ltd.

  Shares: 104,119.00 · Class: 0.2%

• BVF GP HOLDINGS LLC

  Shares: 1,591,306.00 · Class: 3.6%

• BVF PARTNERS L P/IL

  Shares: 1,720,782.00 · Class: 3.8%

• BVF INC/IL

  Shares: 1,720,782.00 · Class: 3.8%

• LAMPERT MARK N

  Shares: 1,720,782.00 · Class: 3.8%

Amounts are as disclosed in this filing. Schedule type alone does not establish investment intent.