AnhCo Nguyen - 17 Aug 2026 Form 4 Insider Report for Atara Biotherapeutics, Inc. (ATRA)

Reporting relationship: President and CEO, Director
Issuer ticker: ATRA
Reported as of: 17 Aug 2026
Net transaction value: -$40,883
SEC form: 4
Accepted by SEC: 26 Aug 2026, 19:45:25 UTC
Prior SEC filing: 20 May 2026
Source filing: View source filing
Reporting owner signature: /s/ AnhCo Nguyen

Key filing fact

AnhCo Nguyen filed Form 4 for Atara Biotherapeutics, Inc. (ATRA) on 26 Aug 2026.

Key facts

This page summarizes AnhCo Nguyen's Form 4 filing for Atara Biotherapeutics, Inc. (ATRA).
1 reported transaction and 0 derivative rows are listed below.
Accepted by SEC: 26 Aug 2026, 19:45.

Change

Previous filing in this sequence was filed on 20 May 2026.
Current net transaction value: -$40,883.

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 0001977970 Primary reporting owner

Nguyen AnhCo

Relationship: President and CEO, Director
Address: C/O ATARA BIOTHERAPEUTICS, INC., 1280 RANCHO CONEJO BOULEVARD, THOUSAND OAKS
Signature: /s/ AnhCo Nguyen
Signature date: 26 Aug 2026

Reported non-derivative transactions

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

ATRA transaction

Common Stock

Sale

Transaction value: $40,883
Shares: -5,062
Change %: -3.7%
Price: $8.08
Shares after: 132,775
Date: 17 Aug 2026
Ownership: Direct
Footnotes: F1, 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

Shares sold automatically to satisfy tax withholding obligations in connection with the vesting of previously granted restricted stock units, pursuant to a sale-to-cover provision in the award agreement.

Footnote F2

The sale price of the reporting person's shares represents the weighted average price of all shares sold by a broker on August 17, 2026, on behalf of a group of employees of the Issuer to satisfy the payment of withholding tax liability of such employees.

SEC remarks

Exhibit List: Exhibit 24 - Power of Attorney