Reporting Manager
Adiumentum Capital Fund I LP
Symbol
ATRA
Shares outstanding
6,853,832 shares
Disclosed Ownership
1,370,081 shares
Ownership
20%
Form type
SCHEDULE 13D/A
Filing time
16 May 2025, 18:28:02 UTC
Date of event
14 May 2025

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Quoteable Key Fact

"Adiumentum Capital Fund I LP disclosed 20% ownership in Atara Biotherapeutics, Inc. Common Stock, par value $0.0001 per share (ATRA) on 14 May 2025."

Quick Takeaways

  • Adiumentum Capital Fund I LP filed SCHEDULE 13D/A for Atara Biotherapeutics, Inc. Common Stock, par value $0.0001 per share (ATRA).
  • Disclosed ownership: 20%.
  • Date of event: 14 May 2025.

What Changed

  • No earlier schedule filing is available for direct comparison.
  • Current filing was accepted on 16 May 2025, 18:28.

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 (3)

Name Ownership Shares Owned sole voting power shared voting power Signature Title CIK
Adiumentum Capital Fund I LP 20% 1,370,081 0 1,370,081 /s/ Gregory A. Ciongoli By: Adiumentum Capital Fund I GP, LLC, its general partner Name: Gregory A. Ciongoli, Title: Managing Member 0002023734
Adiumentum Capital Fund I GP LLC 20% 1,370,081 0 1,370,081 /s/ Gregory A. Ciongoli Name: Gregory A. Ciongoli, Title: Managing Member 0002023736
Gregory A. Ciongoli 20% 1,370,081 0 1,370,081 /s/ Gregory A. Ciongoli Name: Gregory A. Ciongoli 0002023732