ATRA

8-K

false000160446400016044642026-03-162026-03-16

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): March 16, 2026

Atara Biotherapeutics, Inc. (Exact name of Registrant as Specified in Its Charter)

Delaware

001-36548

46-0920988

(State or Other Jurisdiction of Incorporation)

(Commission File Number)

(IRS Employer Identification No.)

1280 Rancho Conejo Blvd

Thousand Oaks, California

91320

(Address of Principal Executive Offices)

(Zip Code)

Registrant’s Telephone Number, Including Area Code: (805) 623-4211

(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: ☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) Securities registered pursuant to Section 12(b) of the Act:

Title of each class

Trading Symbol(s)

Name of each exchange on which registered

Common Stock, par value $0.0001 per share

ATRA

The Nasdaq Stock Market LLC

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter). Emerging growth company ☐ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 2.02 Results of Operations and Financial Condition. On March 16, 2026, the Company announced certain financial results for the fourth quarter and year ended December 31, 2025. A copy of the Company’s press release, titled “Atara Biotherapeutics Announces Fourth Quarter and Full Year 2025 Financial Results and Operational Progress” is furnished as Exhibit 99.1 hereto.

The information set forth in this Item 2.02 and in the press release included as Exhibit 99.1 shall not be deemed “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liabilities of Section 11 and 12(a)(2) of the Securities Act of 1933, as amended, and shall not be incorporated by reference into any filing with the U.S. Securities and Exchange Commission, whether made before or after the date hereof, except as shall be expressly set forth by specific reference in such filing. Item 9.01 Financial Statements and Exhibits. (d) Exhibits.

Exhibit No.

Description

99.1

Press Release, dated March 16, 2026

104

Cover Page Interactive Data File (embedded within the Inline XBRL document)

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

ATARA BIOTHERAPEUTICS, INC.

Date:

March 16, 2026

By:

/s/ Yanina Grant-Huerta

Yanina Grant-Huerta

Chief Accounting Officer (Duly Authorized Officer and Principal Financial and Accounting Officer)

8-K

false 0001604464 0001604464 2026-01-12 2026-01-12

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): January 12, 2026

Atara Biotherapeutics, Inc. (Exact name of Registrant as Specified in Its Charter)

Delaware

001-36548

46-0920988

(State or Other Jurisdiction of Incorporation)

(Commission File Number)

(IRS Employer Identification No.)

1280 Rancho Conejo Blvd

Thousand Oaks, California

91320

(Address of Principal Executive Offices)

(Zip Code) Registrant’s Telephone Number, Including Area Code: (805) 623-4211 (Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class

Trading Symbol(s)

Name of each exchange on which registered

Common Stock, par value $0.0001 per share

ATRA

The Nasdaq Stock Market LLC Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter). Emerging growth company ☐ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 2.02 Results of Operations and Financial Condition. In connection with the press release described in Item 8.01 below, on January 12, 2026, Atara Biotherapeutics, Inc. (the “Company”) announced its cash, cash equivalents and short term investments as of December 31, 2025. The preliminary estimate is based on currently available information and does not present all necessary information for a complete understanding of the Company’s financial condition as of December 31, 2025 or the Company’s results of operations for the fourth quarter ended December 31, 2025. Item 8.01 Other Events On January 12, 2026, the Company issued a press release titled “Atara Biotherapeutics Provides Regulatory and Business Update on EBVALLO™ (tabelecleucel)” announcing that the U.S. Food and Drug Administration issued a Complete Response Letter for the EBVALLO™ (tabelecleucel) Biologics License Application. A copy of the press release is filed as Exhibit 99.1 and incorporated by reference into this Item 8.01. Item 9.01 Financial Statements and Exhibits (d) Exhibits.

Exhibit No.

Description

99.1

Press Release, dated January 12, 2026

104

Cover Page Interactive Data File (embedded within the Inline XBRL document).

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

ATARA BIOTHERAPEUTICS, INC.

Date: January 12, 2026

By:

/s/ AnhCo Thieu Nguyen

AnhCo Thieu Nguyen President and Chief Executive Officer (Duly Authorized Officer and Principal Executive Officer)

8-K

false 0001604464 0001604464 2025-11-12 2025-11-12

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): November 12, 2025

Atara Biotherapeutics, Inc. (Exact name of Registrant as Specified in Its Charter)

Delaware

001-36548

46-0920988

(State or Other Jurisdiction of Incorporation)

(Commission File Number)

(IRS Employer Identification No.)

1280 Rancho Conejo Blvd

Thousand Oaks, California

91320

(Address of Principal Executive Offices)

(Zip Code) Registrant’s Telephone Number, Including Area Code: (805) 623-4211 (Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class

Trading Symbol(s)

Name of each exchange on which registered

Common Stock, par value $0.0001 per share

ATRA

The Nasdaq Stock Market LLC Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter). Emerging growth company ☐ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 2.02 Results of Operations and Financial Condition. On November 12, 2025, the Company announced certain financial results for the third quarter ended September 30, 2025. A copy of the Company’s press release, titled “Atara Biotherapeutics Announces Third Quarter Financial Results and Operational Progress” is furnished as Exhibit 99.1 hereto. The information set forth in this Item 2.02 and in the press release included as Exhibit 99.1 shall not be deemed “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liabilities of Section 11 and 12(a)(2) of the Securities Act of 1933, as amended, and shall not be incorporated by reference into any filing with the U.S. Securities and Exchange Commission, whether made before or after the date hereof, except as shall be expressly set forth by specific reference in such filing. Item 9.01 Financial Statements and Exhibits. (d)  Exhibits.

Exhibit No.

Description

99.1

Press Release, dated November 12, 2025

104

Cover Page Interactive Data File (embedded within the Inline XBRL document)

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

ATARA BIOTHERAPEUTICS, INC.

Date: November 12, 2025

By:

/s/ Yanina Grant-Huerta

Yanina Grant-Huerta

Chief Accounting Officer (Duly Authorized Officer and Principal Financial and Accounting Officer)