Company: ATRA
Filing Date: 2025-01-17
Form Type: S-8
Source: 0001193125-25-008413
Chunk: 0

Company: Atara Biotherapeutics, Inc.
Filing Date: 2025-01-17
Form: S-8
Chunk 0
---
As filed with the Securities and Exchange Commission on January 17, 2025 Registration No. 333- UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM S-8 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 ATARA BIOTHERAPEUTICS, INC. (Exact name of registrant as specified in its charter)

| Delaware                        |     | 46-0920988            |
| (State or other jurisdiction of 
 incorporation or organization)  |     | -I.R.S. Employer      
 Identification Number |

2380 Conejo Spectrum Street, Suite 200 Thousand Oaks, California 91320 (805) 623-4211 (Address, including zip code and telephone number, of Registrant’s principal executive offices) Atara Biotherapeutics, Inc. 2024 Equity Incentive Plan AnhCo Nguyen, Ph.D. President and Chief Executive Officer 2380 Conejo Spectrum Street, Suite 200 Thousand Oaks, California 91320 (805) 623-4211 (Name, address, including zip code and telephone number, including area code, of agent for service) Copies to:

| Eric Hyllengren                                     
 Chief Financial Officer and Chief Operating Officer 
 2380 Conejo Spectrum Street, Suite 200              
 Thousand Oaks, California 91320                     
 (805) 623-4211                                      |     | Carlton Fleming                                               
 Sidley Austin LLP 555                                         
 California Street, Suite 2000 San Francisco, California 94104 
 (415) 772-1200                                                |

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-acceleratedfiler, or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company” and “emerging growth company” in Rule 12b-2of the Exchange Act.

| Large accelerated filer |     | ☐ |     | Accelerated filer         |     | ☐ |
| Non-accelerated filer   |     | ☒ |     | Smaller reporting company |     | ☒ |
|                         |     |   |     | 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