ATRA Form 144: Insider Resale of 4,759 Shares

Issuer files a Form 144 notice to sell 4,759 shares of common stock.

Rhea-AI Filing Summary

Issuer files a Form 144 notice to sell 4,759 shares of common stock. The filing states these shares result from the settlement of vested RSUs issued under an S-8 registration plan on 03/01/2026. The submission appears as a routine insider resale notice under applicable resale rules.

Insights

Securities Counsel

Routine Rule 144 resale notice for vested RSUs; timing and source are explicit.

The filing lists 4,759 shares described as settled from vested RSUs under an S-8 registration plan on 03/01/2026. This indicates the holder reported an intention to sell shares derived from equity compensation.

Cash‑flow treatment and any broker or distribution methods are not specified in the excerpt; subsequent transaction details will appear in transfer records or separate notices if sales occur.

FAQ

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

What does the ATRA Form 144 filing report?

The filing reports a notice to sell 4,759 shares of common stock from vested RSUs. The shares are described as settled under an S-8 registration plan on 03/01/2026, indicating equity compensation origin.

When were the RSU shares for ATRA settled?

The excerpt shows the RSUs were settled on 03/01/2026. The Form 144 lists that settlement date as the source of the 4,759 shares reported for resale.

Does the Form 144 indicate who will receive proceeds from the sale?

The provided excerpt does not specify proceeds recipients. It identifies the shares as from vested RSUs under the issuer's S-8 plan; cash‑flow treatment is not detailed in the excerpt.

Is this Form 144 a material corporate event for ATRA?

No. This is a routine resale notice for equity compensation shares. The filing lists 4,759 RSU‑derived shares; it does not disclose material operational or financial changes for the company.

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

See more from StockTitan in Google Search and AI answers. Adds StockTitan as a preferred source · opens Google

Add on Google Not now

Accepted by SEC EDGAR 03/02/2026 - 06:24 PM EST 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	0002064348
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	Grant-Huerta Yanina
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	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	2355	12764.10	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			4759	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 Yanina Grant-Huerta
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)