Atara CEO granted 81,100-share stock award

Nguyen AnhCo reported acquisition or exercise transactions in this Form 4 filing.

Rhea-AI Filing Summary

Nguyen AnhCo reported acquisition or exercise transactions in this Form 4 filing.

Atara Biotherapeutics reported that President and CEO Nguyen AnhCo received a grant of 81,100 shares of common stock in the form of restricted stock units at no cash cost. These RSUs vest in eight equal quarterly installments beginning on the second Quarterly Vesting Date after March 9, 2026, and then on subsequent March 1, May 15, August 15, and November 15 vesting dates, subject to continued employment. Following this award, AnhCo directly holds 143,078 shares of Atara common stock.

Insider Trade Summary

Grant/Award: 81,100 shares

Grant/Award 1 txn

Insider Nguyen AnhCo

Role President and CEO

Type	Security	Shares	Price	Value
Grant/Award	Common Stock	81,100	$0.00	$0.00

Holdings After Transaction: Common Stock — 143,078 shares (Direct)

Footnotes (1)

1. F1. These restricted stock units ("RSUs") vest as to 1/8th of the total number of shares (rounded down to the next whole number of shares) on the second Quarterly Vesting Date (as defined below) following March 9, 2026, and as to 1/8th of the total number of shares (rounded down to the next whole number of shares) on the next seven Quarterly Vesting Dates, such that all of the shares subject to the RSUs shall be vested on the last Quarterly Vesting Date, subject to the reporting person's continuous employment. "Quarterly Vesting Date" means March 1, May 15, August 15, and November 15 of each year, provided that if such date falls on a weekend or holiday, the Quarterly Vesting Date shall be the first business day after such date.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What insider transaction did Atara Biotherapeutics (ATRA) report for its CEO?

Atara Biotherapeutics reported a stock-based compensation grant to its CEO. President and CEO Nguyen AnhCo received 81,100 restricted stock units tied to Atara common shares, awarded at no cash cost as part of his equity compensation, according to the Form 4 filing.

How many Atara Biotherapeutics (ATRA) shares were granted to CEO Nguyen AnhCo?

CEO Nguyen AnhCo was granted 81,100 restricted stock units. Each unit represents one share of Atara common stock. The award increases his equity-based compensation and is structured to vest over time, aligning his incentives with the company’s long-term performance.

What is the vesting schedule for Nguyen AnhCo’s 81,100 RSUs at Atara Biotherapeutics (ATRA)?

The 81,100 RSUs vest in eight quarterly installments. One-eighth vests on the second Quarterly Vesting Date after March 9, 2026, and one-eighth on each of the next seven March 1, May 15, August 15, and November 15 vesting dates, contingent on continued employment.

How many Atara Biotherapeutics (ATRA) shares does the CEO hold after this Form 4 transaction?

After the grant, CEO Nguyen AnhCo directly holds 143,078 shares. This total reflects his ownership following the 81,100-share restricted stock unit award and shows his ongoing equity stake in Atara Biotherapeutics as disclosed in the Form 4.

Was the Atara Biotherapeutics (ATRA) CEO’s Form 4 transaction an open-market stock purchase?

No, the CEO’s transaction was not an open-market purchase. The Form 4 describes a grant or award acquisition of 81,100 restricted stock units at a price of $0.0000 per share, reflecting stock-based compensation rather than a cash-funded market buy.

What does this Atara Biotherapeutics (ATRA) Form 4 filing indicate about executive compensation?

The filing highlights equity-based compensation for Atara’s CEO. Granting 81,100 restricted stock units with multi-year vesting ties a significant portion of President and CEO Nguyen AnhCo’s compensation to future company performance and continued service.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 03/11/2026 - 05:46 PM Learn about SEC filing dates

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Nguyen AnhCo

(Last) (First) (Middle)

C/O ATARA BIOTHERAPEUTICS, INC.

1280 RANCHO CONEJO BOULEVARD

(Street)

THOUSAND OAKS CA 91320

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Atara Biotherapeutics, Inc. [ ATRA ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	President and CEO

3. Date of Earliest Transaction (Month/Day/Year)
03/09/2026

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	03/09/2026		A		81,100(1)	A	$0	143,078	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. These restricted stock units ("RSUs") vest as to 1/8th of the total number of shares (rounded down to the next whole number of shares) on the second Quarterly Vesting Date (as defined below) following March 9, 2026, and as to 1/8th of the total number of shares (rounded down to the next whole number of shares) on the next seven Quarterly Vesting Dates, such that all of the shares subject to the RSUs shall be vested on the last Quarterly Vesting Date, subject to the reporting person's continuous employment. "Quarterly Vesting Date" means March 1, May 15, August 15, and November 15 of each year, provided that if such date falls on a weekend or holiday, the Quarterly Vesting Date shall be the first business day after such date.

	/s/ John Chao, Attorney-in-Fact for AnhCo Nguyen	03/11/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.