SCHEDULE 13D/A

Jade Biosciences Inc

Common Stock, $0.0001 par value · CUSIP: 008064206

Event date: 2025-10-06

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

• Fairmount Funds Management LLCReported CIK 0001802528

  Shares: 10,353,875.00 · Class: 19.99%

• Fairmount Healthcare Fund II L.P.Reported CIK 0001769651

  Shares: 7,698,058.00 · Class: 14.86%

• Fairmount Healthcare Co-Invest IV L.P.Reported CIK 0002042283

  Shares: 2,655,817.00 · Class: 5.77%

• Peter Evan HarwinReported CIK 0001663607

  Shares: 10,353,875.00 · Class: 19.99%

• Tomas KiselakReported CIK 0001830177

  Shares: 10,353,875.00 · Class: 19.99%

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