ATRA Rule 144 notice to sell 7,788 shares

ATRA reported a Rule 144 notice to sell 7,788 shares of Common Stock.

Rhea-AI Filing Summary

ATRA reported a Rule 144 notice to sell 7,788 shares of Common Stock. The filing shows these shares relate to the settlement of vested RSUs issued under an S-8 registration plan and are dated 03/01/2026.

The filing lists the transaction as equity compensation for services rendered and identifies Morgan Stanley Smith Barney LLC Executive Services as the broker.

Insights

Corporate Counsel

Routine Rule 144 sale notice tied to RSU settlement; legal formality, not a novel issuance.

The filing documents the planned sale of 7,788 shares arising from the settlement of vested RSUs under an S-8 registration plan on 03/01/2026. This is presented as equity compensation for services rendered.

Timing and mechanics follow Rule 144 notice practice; cash‑flow treatment and specific distribution method are not detailed in the excerpt.

Compensation Analyst

Compensation event: vested RSUs converted to shares and slated for sale under Rule 144.

The record ties the 7,788-share item to vested RSUs settled under an S-8 plan, indicating payout of equity compensation rather than a primary capital raise. The broker shown is Morgan Stanley Smith Barney LLC Executive Services.

Subsequent filings may disclose whether proceeds were retained by the issuer or passed to the holder; the excerpt does not include proceeds allocation.

FAQ

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

What does ATRA's Form 144 disclose?

The Form 144 discloses a planned sale of 7,788 shares of common stock. The filing ties the shares to the settlement of vested RSUs under an S-8 registration plan and is dated 03/01/2026.

Why were the 7,788 ATRA shares reported?

The shares were reported because they arose from the settlement of vested RSUs issued under an S-8 registration plan. The filing characterizes the transaction as equity compensation for services rendered on 03/01/2026.

Who is listed as the broker in the ATRA filing?

The filing lists Morgan Stanley Smith Barney LLC Executive Services as the broker for the transaction. The broker address and NASDAQ designation appear alongside the security details in the excerpt.

Does the Form 144 show proceeds or issuer receipt for ATRA?

The excerpt states the shares result from RSU settlement under an S-8 plan and labels the event as equity compensation. The filing does not include explicit proceeds allocation or net cash‑flow details in the provided text.

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

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Accepted by SEC EDGAR 03/02/2026 - 06:25 PM Learn about SEC filing dates

Form 144 Filer Information	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 144 NOTICE OF PROPOSED SALE OF SECURITIES PURSUANT TO RULE 144 UNDER THE SECURITIES ACT OF 1933
FORM 144

144: Filer Information

Filer CIK	0001977970
Filer CCC	XXXXXXXX
Is this a LIVE or TEST Filing?	LIVE TEST
Submission Contact Information
Name
Phone
E-Mail Address

144: Issuer Information

Name of Issuer	Atara Biotherapeutics, Inc.
SEC File Number	001-36548
Address of Issuer	c/o Atara Biotherapeutics, Inc. 1280 Rancho Conejo Boulevard Thousand Oaks CALIFORNIA 91320
Phone	805-623-4211
Name of Person for Whose Account the Securities are To Be Sold	Nguyen AnhCo
See the definition of "person" in paragraph (a) of Rule 144. Information is to be given not only as to the person for whose account the securities are to be sold but also as to all other persons included in that definition. In addition, information shall be given as to sales by all persons whose sales are required by paragraph (e) of Rule 144 to be aggregated with sales for the account of the person filing this notice.
Relationship to Issuer	Director
Relationship to Issuer	Officer

144: Securities Information

Title of the Class of Securities To Be Sold	Name and Address of the Broker	Number of Shares or Other Units To Be Sold	Aggregate Market Value	Number of Shares or Other Units Outstanding	Approximate Date of Sale	Name the Securities Exchange
Common Stock	Morgan Stanley Smith Barney LLC Executive Services 200 W Civic Center Drive, 4th Floor Sandy UT 84070	3355	18184.10	7323897	03/02/2026	NASDAQ

Furnish the following information with respect to the acquisition of the securities to be sold and with respect to the payment of all or any part of the purchase price or other consideration therefor:

144: Securities To Be Sold

Title of the Class	Date you Acquired	Nature of Acquisition Transaction	Name of Person from Whom Acquired	Is this a Gift?	Date Donor Acquired	Amount of Securities Acquired	Date of Payment	Nature of Payment *
Common Stock	03/01/2026	Settlement of vested RSUs issued under an S-8 Registration Plan	Issuer			7788	03/01/2026	Equity compensation for services rendered

* If the securities were purchased and full payment therefor was not made in cash at the time of purchase, explain in the table or in a note thereto the nature of the consideration given. If the consideration consisted of any note or other obligation, or if payment was made in installments describe the arrangement and state when the note or other obligation was discharged in full or the last installment paid.

Furnish the following information as to all securities of the issuer sold during the past 3 months by the person for whose account the securities are to be sold.

144: Securities Sold During The Past 3 Months

Nothing to Report

144: Remarks and Signature

Remarks	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.
Date of Notice	03/02/2026
ATTENTION:
The person for whose account the securities to which this notice relates are to be sold hereby represents by signing this notice that he does not know any material adverse information in regard to the current and prospective operations of the Issuer of the securities to be sold which has not been publicly disclosed. If such person has adopted a written trading plan or given trading instructions to satisfy Rule 10b5-1 under the Exchange Act, by signing the form and indicating the date that the plan was adopted or the instruction given, that person makes such representation as of the plan adoption or instruction date.
Signature	/s/ John Chao, Attorney-in-Fact for AnhCo Nguyen
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)