Form
SCHEDULE 13D/A
Active or control-oriented beneficial ownership filing.
Adiumentum Capital Fund I LP - 14 May 2025 SCHEDULE 13D/A Report for Atara Biotherapeutics, Inc. Common Stock, par value $0.0001 per share (ATRA)
- Filing manager
- Adiumentum Capital Fund I LP
- Reporting owner
- Adiumentum Capital Fund I LP
- Beneficially owned shares
- 1,370,081 shares
- Large-stake signal
-
Ownership
20%Beneficial ownership of this reported class.
Shares
1,370,081 sharesShares beneficially owned as disclosed.
Event date
14 May 2025Date tied to the ownership event or amendment.
Accepted by SEC
16 May 2025EDGAR acceptance date.
How to read this large-stake filing
- Schedule 13D/G filings focus on beneficial ownership stakes, not a full portfolio.
- Compare this filing with the holder history and issuer page before treating the percentage as a current position.
- Use amendments to understand whether the disclosed stake increased, decreased, or changed reporting status.
- Class ownership
- 20%
- Symbol
- ATRA
- Shares outstanding
- 6,853,832 shares
- SEC form
- SCHEDULE 13D/A
- Accepted by SEC
- 16 May 2025, 18:28:02 UTC
- Event date
- 14 May 2025
- Source filing
- View source filing
Ownership signal
CIK-linked ownership evidence from parsed SEC filings.
2 signals
Subject security
Names, identifiers, and filing context for this profile.
2 source fields
Source evidence
Original filing metadata and source links for verification.
4 source fields
Key filing 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.
Key facts
- 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.
Change
- No earlier schedule filing is available for direct comparison.
- Current filing was accepted on 16 May 2025, 18:28.
Research use
- This page turns one Schedule 13D/G filing into a quick large-stake read before the raw reporting-person rows.
- Use the linked SEC filing as the source of truth for ownership percentages, shares, and reporting-party details.
Evidence
Backed by Schedule 13D/13G
View source filing
Beneficial ownership values are sourced from the original SEC Schedule 13D/13G filing.
Reporting persons
Disclosed reporting parties (3)
Names, ownership percentages, voting power, signatures, titles, and CIKs as disclosed in this Schedule 13D/G filing.
| 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 |
CIK / CUSIP context first