Statement of Changes in Beneficial Ownership (Form 4)

FORM 4 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 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person * Redmile Group, LLC 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 _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 900 LARKSPUR LANDING CIRCLE, SUITE 270 3. Date of Earliest Transaction (Month/Day/Year) 07/22/2026 (Street) LARKSPUR, CA 94939 4. If Amendment, Date Original Filed (Month/Day/Year) 6. Individual or Joint/Group Filing (Check Applicable Line) ___ Form filed by One Reporting Person _X_ Form filed by More than One Reporting Person (City) (State) (Zip) 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 07/22/2026 M(5) 195,211 A (5) 636,912 I See Footnote(4) Common Stock 07/22/2026 F(5) 60 D (5) 636,852 I See Footnote(4)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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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 Underlying Securities (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 of Derivative Security: 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
Pre-Funded Warrants to Purchase Common Stock	$0.0025(1)(8)	07/22/2026		M(5)			101,089	(1)(8)	(1)(8)	Common Stock	101,089	$ 0	0	I	See Footnote(4)
Pre-Funded Warrants to Purchase Common Stock	$0.0025(2)(8)	07/22/2026		M(5)			38,735	(2)(8)	(2)(8)	Common Stock	38,735	$ 0	0	I	See Footnote(4)
Pre-Funded Warrants to Purchase Common Stock	$0.0025(3)(8)	07/22/2026		M(5)			55,387	(3)(8)	(3)(8)	Common Stock	55,387	$ 0	0	I	See Footnote(4)
Pre-Funded Warrants to Purchase Common Stock	$0.0025(6)(8)							(6)(8)	(6)(8)	Common Stock	1,090,907		1,090,907	I	See Footnote(4)
Pre-Funded Warrants to Purchase Common Stock	$0.0001(7)(8)							(7)(8)	(7)(8)	Common Stock	2,126,725		2,126,725	I	See Footnote(4)

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Redmile Group, LLC 900 LARKSPUR LANDING CIRCLE SUITE 270 LARKSPUR, CA 94939	X
Green Jeremy C/O REDMILE GROUP, LLC (NY OFFICE) 45 W. 27TH STREET, FLOOR 11 NEW YORK, NY 10001	X

Signatures

By: /s/ Jeremy Green, Managing Member of Redmile Group, LLC		07/24/2026
**Signature of Reporting Person		Date
/s/ Jeremy Green		07/24/2026
**Signature of Reporting Person		Date

Explanation of Responses:

*	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).
(1)	The Pre-Funded Warrants are exercisable at any time on or after the original issuance on July 23, 2019 until the seven-year anniversary of the original issuance date, at an exercise price equal to $0.0025 per share, subject to a 9.99% beneficial ownership blocker.
(2)	The Pre-Funded Warrants are exercisable at any time on or after the original issuance on May 29, 2020 until the seven-year anniversary of the original issuance date, at an exercise price equal to $0.0025 per share, subject to a 9.99% beneficial ownership blocker.
(3)	The Pre-Funded Warrants are exercisable at any time on or after the original issuance on December 11, 2020 until the seven-year anniversary of the original issuance date, at an exercise price equal to $0.0025 per share, subject to a 9.99% beneficial ownership blocker.
(4)	The reported securities are directly owned by certain private funds managed by Redmile Group, LLC (collectively, the "Funds") and may be deemed beneficially owned by Redmile Group, LLC ("Redmile") as investment manager of the Funds. The reported securities may also be deemed beneficially owned by Jeremy Green as the principal of Redmile. Each of Redmile and Mr. Green (the "Reporting Persons") disclaims beneficial ownership of the reported securities except to the extent of their pecuniary interest therein, if any. This report shall not be deemed an admission that such Reporting Persons are the beneficial owners of the securities for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or for any other purpose.
(5)	On July 22, 2026, the Reporting Persons exercised the reported Pre-Funded Warrants through a "cashless exercise" resulting in the Issuer withholding 60 shares of Common Stock to pay the exercise price and issuing the remaining 195,151 shares of Common Stock to the applicable Funds. The number of shares withheld to pay the aggregate exercise price for the cashless exercise of the Pre-Funded Warrants was based on the closing sale price per share of the Common Stock on the trading date immediately prior to the exercise date, per the terms of the Pre-Funded Warrants.
(6)	The Pre-Funded Warrants are exercisable at any time on or after the original issuance date, at an exercise price equal to $0.0025 per share, subject to a 9.99% beneficial ownership blocker. The Pre-Funded Warrants have no expiration date.
(7)	The Pre-Funded Warrants are exercisable at any time on or after the original issuance date, at an exercise price equal to $0.0001 per share, subject to a 9.99% beneficial ownership blocker. The Pre-Funded Warrants have no expiration date.
(8)	The previous report on Form 3 inadvertently indicated that all of the Pre-Funded Warrants beneficially owned by the Reporting Persons have an exercise price of $0.0001 per share and no expiration date. Footnotes (1), (2), (3), (6) and (7) and the related disclosures correct the Form 3 with respect to the terms of the Pre-Funded Warrants beneficially owned by the Reporting Persons.
Remarks: Mr. Nachi Subramanian, a member of the board of directors of the Issuer and a managing director of Redmile, was elected to the board of the Issuer as a representative of Redmile and its affiliates. As a result, the Reporting Persons are directors by deputization for purposes of Section 16 of the Securities Exchange Act of 1934, as amended.

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