Fairmount Funds Management LLC - 06 Oct 2025 SCHEDULE 13D/A Report for Jade Biosciences, Inc. Common Stock, $0.0001 par value (JBIO)

Filing Manager
Fairmount Funds Management LLC
Reporting Manager
Fairmount Funds Management LLC
Security
Jade Biosciences, Inc. Common Stock, $0.0001 par value
Symbol
JBIO
Shares outstanding
51,795,273 shares
Disclosed Ownership
10,353,875 shares
Ownership
20%
Form type
SCHEDULE 13D/A
Filing time
08 Oct 2025, 16:15:29 UTC
Date of event
06 Oct 2025
Previous filing
01 May 2025
SEC
View on sec.gov

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Quoteable Key Fact

"Fairmount Funds Management LLC disclosed 20% ownership in Jade Biosciences, Inc. Common Stock, $0.0001 par value (JBIO) on 06 Oct 2025."

Quick Takeaways

  • Fairmount Funds Management LLC filed SCHEDULE 13D/A for Jade Biosciences, Inc. Common Stock, $0.0001 par value (JBIO).
  • Disclosed ownership: 20%.
  • Date of event: 06 Oct 2025.

What Changed

  • Previous schedule filing date: 01 May 2025.
  • Current filing was accepted on 08 Oct 2025, 16:15.

Why This Matters

  • This page explains what this Schedule 13D/13G filing tells you before manager-level rows.
  • You can verify ownership claims directly against the original SEC filing.

Official SEC Source

Backed by Schedule 13D/13G

Beneficial ownership values are sourced from the original SEC Schedule 13D/13G filing.

See Original Filing

Reporting Managers (5)

Name Ownership Shares Owned sole voting power shared voting power Signature Title CIK
Fairmount Funds Management LLC 20% 10,353,875 0 10,353,875 /s/ Peter Harwin Peter Harwin, Managing Member 0001802528
Fairmount Healthcare Fund II L.P. 15% 7,698,058 0 7,698,058 /s/ Peter Harwin Peter Harwin, Managing Member 0001769651
Fairmount Healthcare Co-Invest IV L.P. 5.8% 2,655,817 0 2,655,817 /s/ Peter Harwin Peter Harwin, Managing Member 0002042283
Peter Evan Harwin 20% 10,353,875 0 10,353,875 /s/ Peter Harwin Peter Harwin 0001663607
Tomas Kiselak 20% 10,353,875 0 10,353,875 /s/ Tomas Kiselak Tomas Kiselak 0001830177

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