Gregory A. Ciongoli - 09 Jun 2026 Form 4 Insider Report for Atara Biotherapeutics, Inc. (ATRA)

Reporting relationship: Director, Other*, 10%+ Owner
Issuer ticker: ATRA
Reported as of: 09 Jun 2026
Net transaction value: $0
SEC form: 4
Accepted by SEC: 11 Jun 2026, 16:36:04 UTC
Prior SEC filing: 12 Jan 2026
Source filing: View source filing
Reporting owner signature: /s/ John Chao, Attorney-in-Fact for Gregory A. Ciongoli

Key filing fact

Gregory A. Ciongoli filed Form 4 for Atara Biotherapeutics, Inc. (ATRA) on 11 Jun 2026.

Key facts

This page summarizes Gregory A. Ciongoli's Form 4 filing for Atara Biotherapeutics, Inc. (ATRA).
1 reported transaction and 0 derivative rows are listed below.
Accepted by SEC: 11 Jun 2026, 16:36.

Change

Previous filing in this sequence was filed on 12 Jan 2026.
Current net transaction value: $0.

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

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0002023732 Primary reporting owner

Ciongoli Gregory Austin

Relationship: Director, Other*, 10%+ Owner
Address: C/O ATARA BIOTHERAPEUTICS, INC., 1280 RANCHO CONEJO BOULEVARD, THOUSAND OAKS
Signature: /s/ John Chao, Attorney-in-Fact for Gregory A. Ciongoli
Signature date: 11 Jun 2026

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

ATRA transaction

Common Stock

Award

Transaction value
Shares: +12,000
Change %
Price: $0.000000^*
Shares after: 12,000
Date: 09 Jun 2026
Ownership: Direct
Footnotes: F1

ATRA holding

Common Stock

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after: 1,209,395
Date: 09 Jun 2026
Ownership: See Footnote
Footnotes: F2

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Explanation of responses 2 footnotes

Footnote F1

These restricted stock units shall vest on the earlier of June 9, 2027 or the date of the next annual meeting of stockholders, subject to the Reporting Person's continuous service.

Footnote F2

The securities reported on this row are directly held by Adiumentum Capital Fund I LP, a limited partnership organized under the laws of Delaware ("Adiumentum"). Adiumentum Capital Fund I GP LLC, a limited liability company organized under the laws of Delaware ("Adiumentum GP"), is the general partner of Adiumentum. Gregory A. Ciongoli is the managing partner of Adiumentum and the managing member of Adiumentum GP. Each of Adiumentum, Adiumentum GP, and Mr. Ciongoli may be deemed to have the shared power to vote or direct the vote (and the shared power to dispose or direct the disposition of) the securities that are directly held by Adiumentum. Each of Adiumentum, Adiumentum GP, and Mr. Ciongoli may be deemed to have a pecuniary interest in the securities that are directly held by Adiumentum, but disclaims any beneficial ownership of such securities, except to the extent of any pecuniary interest therein.

SEC remarks

Exhibit List: Exhibit 24 - Power of Attorney. Mr. Ciongoli serves as a director on the Board of Directors of the Issuer and, as a result, Adiumentum and Adiumentum GP are directors by deputization for purposes of Section 16 of the Securities Exchange Act of 1934, as amended. Neither Adiumentum nor Adiumentum GP have a pecuniary interest in the restricted stock units awarded to Mr. Ciongoli as reported in this Form 4, and therefore Adiumentum and Adiumentum GP have been excluded as reporting persons from this Form 4.