Key facts
- This page summarizes EcoR1 Capital, LLC's Form 4 filing for Atara Biotherapeutics, Inc. (ATRA).
- 1 reported transaction and 0 derivative rows are listed below.
- Accepted by SEC: 11 May 2026, 17:34.
EcoR1 Capital, LLC - 07 May 2026 Form 4 Insider Report for Atara Biotherapeutics, Inc. (ATRA)
- Reporting relationship
- 10%+ Owner
- Issuer ticker
- ATRA
- Reported as of
- 07 May 2026
- Net transaction value
- +$4,744,255
- SEC form
- 4
- Accepted by SEC
- 11 May 2026, 17:34:20 UTC
- Prior SEC filing
- 22 Apr 2026
- Source filing
- View source filing
- Reporting owner signature
- /s/ Oleg Nodelman, Manager of EcoR1 Capital, LLC
Source evidence
Original filing metadata and source links for verification.
4 source fields
Reporting owner
1 detail
Key filing fact
EcoR1 Capital, LLC filed Form 4 for Atara Biotherapeutics, Inc. (ATRA) on 11 May 2026.
Change
- Previous filing in this sequence was filed on 22 Apr 2026.
- Current net transaction value: +$4,744,255.
Research use
- This tells you what this filing adds before you inspect full transaction and derivative tables.
- You can trace every row back to the original SEC filing document.
Evidence
Filed on Form 4
View source filing
Ownership activity is grounded in SEC Form 4 disclosures.
Reporting Owners (1)
CIK 0001587114
Primary reporting owner
EcoR1 Capital, LLC
- Relationship
- 10%+ Owner
- Address
- 357 TEHAMA STREET #3, SAN FRANCISCO
- Signature
- /s/ Oleg Nodelman, Manager of EcoR1 Capital, LLC
- Signature date
- 11 May 2026
Reported non-derivative transactions
Shares, units, or other non-derivative securities reported in this filing.
ATRA
transaction
Common Stock
Purchase
- Transaction value
- $4,744,255
- Shares
- +507,407
- Change %
- +49%
- Price
- $9.35
- Shares after
- 1,552,000
- Date
- 07 May 2026
- Ownership
- See Note
- Footnotes
- F1, F2, F3, F4
* marks a reported price that did not pass the local price check.
Additional SEC filing notes
Filing notes and footnotes
Explanation of responses 4 footnotes
Footnote F1
The reporting persons are EcoR1 Capital, LLC ("EcoR1"), Oleg Nodelman and EcoR1 Capital Fund Qualified, L.P. ("Qualified Fund"). EcoR1 is the general partner and investment adviser of private funds, including Qualified Fund (the "Funds"). Mr. Nodelman is the manager and controller owner of EcoR1. EcoR1 is filing this Form 4 for itself, Mr. Nodelman and Qualified Fund. The reporting persons are filing this Form 4 jointly, but not as a group, and each expressly disclaims membership in a group within the meaning of Rule 13d-5(b) under the Securities Exchange Act of 1934. The Funds hold these securities directly for the benefit of their investors. EcoR1 may be deemed to indirectly beneficially own them as the investment adviser to the Funds. Mr. Nodelman may be deemed to indirectly beneficially own them as the control person of EcoR1. The reporting persons disclaim beneficial ownership of the securities except to the extent of their respective pecuniary interests therein.
Footnote F2
Qualified Fund purchased 474,780 of the shares puchased in this transaction.
Footnote F3
The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $8.85 to $9.39 inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.
Footnote F4
After this transaction, Qualified Fund held 1,445,609 shares of the Issuer's Common Stock.