# EDGAR Filing Document

**Accession Number:** 0001425738
**File Stem:** 0001104659-26-061506
**Filing Date:** 2026-5
**Character Count:** 16281
**Document Hash:** 4707b29da52844ae8b31791928af6d6b
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001104659-26-061506.hdr.sgml**: 20260514

**ACCESSION NUMBER**: 0001104659-26-061506

**CONFORMED SUBMISSION TYPE**: SCHEDULE 13D/A

**PUBLIC DOCUMENT COUNT**: 1

**FILED AS OF DATE**: 20260514

**DATE AS OF CHANGE**: 20260514

**SUBJECT COMPANY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Atara Biotherapeutics, Inc.
- **CENTRAL INDEX KEY:** 0001604464
- **STANDARD INDUSTRIAL CLASSIFICATION:** BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES) [2836]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 460920988
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D/A
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 005-88393
- **FILM NUMBER:** 26981652

**BUSINESS ADDRESS:**
- **STREET 1:** 1280 RANCHO CONEJO BLVD
- **CITY:** THOUSAND OAKS
- **STATE:** CA
- **ZIP:** 91320
- **BUSINESS PHONE:** 805-623-4211

**MAIL ADDRESS:**
- **STREET 1:** 1280 RANCHO CONEJO BLVD
- **CITY:** THOUSAND OAKS
- **STATE:** CA
- **ZIP:** 91320
**FILED BY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Redmile Group, LLC
- **CENTRAL INDEX KEY:** 0001425738

**ORGANIZATION NAME:**
- **EIN:** 208592298
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D/A

**BUSINESS ADDRESS:**
- **STREET 1:** 900 LARKSPUR LANDING CIRCLE
- **STREET 2:** SUITE 270
- **CITY:** LARKSPUR
- **STATE:** CA
- **ZIP:** 94939
- **BUSINESS PHONE:** 415-489-9980

**MAIL ADDRESS:**
- **STREET 1:** 900 LARKSPUR LANDING CIRCLE
- **STREET 2:** SUITE 270
- **CITY:** LARKSPUR
- **STATE:** CA
- **ZIP:** 94939

### UNITED STATES SECURITIES AND EXCHANGE COMMISSION
**Washington, D.C. 20549**

## SCHEDULE 13D

### Under the Securities Exchange Act of 1934

**(Amendment No. 2)**

**Atara Biotherapeutics, Inc.**

*(Name of Issuer)*

**Common Stock, par value $0.0001 per share**

*(Title of Class of Securities)*

**—**

*(CUSIP Number)*

**Josh Garcia**<br>Redmile Group, LLC<br>900 Larkspur Landing Circle, Suite 270<br>Larkspur CA 94939<br>(415) 489-9980

*(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)*

**05/12/2026**

*(Date of Event Which Requires Filing of this Statement)*

| **CUSIP No.** | **—** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Redmile Group, LLC** | Name of reporting person<br>**Redmile Group, LLC** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**OO** | Source of funds (See Instructions)<br>**OO** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**DELAWARE** | Citizenship or place of organization<br>**DELAWARE** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**950994.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**950994.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**950994.00** | Aggregate amount beneficially owned by each reporting person<br>**950994.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**9.9%** | Percent of class represented by amount in Row (11)<br>**9.9%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**IA** | Type of Reporting Person (See Instructions)<br>**IA** | |

---

**Comment for Reporting Person:** (1) The source of funds was working capital of certain private investment funds managed by Redmile Group, LLC (the "Redmile Funds"), including Redmile Biopharma Investments II, L.P. ("RBI II") and Redmile Strategic Long Only Trading Sub, Ltd. ("Redmile Long Only").

(2) The information in Item 5(a) relating to the shares of common stock, par value $0.0001 per share, of the Issuer (the "Common Stock") that are or may be deemed beneficially owned by Redmile Group, LLC ("Redmile") and the calculation of the percent of such class of securities are incorporated by reference herein.

| **CUSIP No.** | **—** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Jeremy C. Green** | Name of reporting person<br>**Jeremy C. Green** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**OO** | Source of funds (See Instructions)<br>**OO** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**X0** | Citizenship or place of organization<br>**X0** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**950994.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**950994.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**950994.00** | Aggregate amount beneficially owned by each reporting person<br>**950994.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**9.9%** | Percent of class represented by amount in Row (11)<br>**9.9%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**IN** | Type of Reporting Person (See Instructions)<br>**IN** | |

---

**Comment for Reporting Person:** (1) The source of funds was working capital of the Redmile Funds, including RBI II and Redmile Long Only.

(2) The information in Item 5(a) relating to the shares of Common Stock that are or may be deemed beneficially owned by Jeremy Green and the calculation of the percent of such class of securities are incorporated by reference herein.

| **CUSIP No.** | **—** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Redmile Biopharma Investments II, L.P.** | Name of reporting person<br>**Redmile Biopharma Investments II, L.P.** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**WC** | Source of funds (See Instructions)<br>**WC** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**DELAWARE** | Citizenship or place of organization<br>**DELAWARE** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**651924.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**651924.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**651924.00** | Aggregate amount beneficially owned by each reporting person<br>**651924.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**6.9%** | Percent of class represented by amount in Row (11)<br>**6.9%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**PN** | Type of Reporting Person (See Instructions)<br>**PN** | |

---

**Comment for Reporting Person:** (1) The information in Item 5(a) relating to the shares of Common Stock that are or may be deemed beneficially owned by RBI II and the calculation of the percent of such class of securities are incorporated by reference herein.

| **CUSIP No.** | **—** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Redmile Strategic Long Only Trading Sub, Ltd.** | Name of reporting person<br>**Redmile Strategic Long Only Trading Sub, Ltd.** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**WC** | Source of funds (See Instructions)<br>**WC** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**CAYMAN ISLANDS** | Citizenship or place of organization<br>**CAYMAN ISLANDS** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**576148.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**576148.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**576148.00** | Aggregate amount beneficially owned by each reporting person<br>**576148.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**6.1%** | Percent of class represented by amount in Row (11)<br>**6.1%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**CO** | Type of Reporting Person (See Instructions)<br>**CO** | |

---

**Comment for Reporting Person:** (1) The information in Item 5(a) relating to the shares of Common Stock that are or may be deemed beneficially owned by Redmile Long Only and the calculation of the percent of such class of securities are incorporated by reference herein.

**Item 1. Security and Issuer**

**(a) Title of Class of Securities:**
Common Stock, par value $0.0001 per share

**(b) Name of Issuer:**
Atara Biotherapeutics, Inc.

**(c) Address of Issuer's Principal Executive Offices:**
1280 Rancho Conejo Blvd, Thousand Oaks, CA, 91320

**Item 5. Interest in Securities of the Issuer**

**(a)**
Item 5(a) of the Prior Schedule 13D is hereby amended and restated in its entirety as follows:

The aggregate amount of shares of Common Stock that may be deemed beneficially owned by the Reporting Persons is comprised of (i) 441,701 shares of Common Stock held by the Redmile Funds, including the 142,631 shares of Common Stock directly held by RBI II and the 66,855 shares of Common Stock directly held by Redmile Long Only, and (ii) 509,293 shares of Common Stock issuable upon the exercise of the Warrants held by the Redmile Funds.

The shares of Common Stock issuable upon the exercise of the Warrants represent the maximum number of shares of Common Stock that could be issued under the 9.99% beneficial ownership limitation (the "Beneficial Ownership Limitation"). Subject in each case to the Beneficial Ownership Limitation, the Redmile Funds directly hold 3,412,843 Warrants, including the 2,054,155 Warrants directly held by RBI II and the 827,581 Warrants directly held by Redmile Long Only.  All of the reported securities are directly owned by certain investment vehicles for which Redmile is the investment manager (the "Redmile Funds"), including RBI II and Redmile Long Only. Redmile may be deemed to beneficially own these securities in its capacity as the investment manager with discretion to vote and dispose of the securities held by the Redmile Funds. Mr. Green also may be deemed to beneficially own these securities as the principal of Redmile. Redmile and Mr. Green each disclaim beneficial ownership of these securities, except to the extent of its or his pecuniary interest in such securities, if any.

Percentage for each Reporting Person is based on the sum of: (i) 9,010,172 shares of Common Stock outstanding as of May 8, 2026, as reported by the Issuer in its Form 10-Q for the quarterly period ended March 31, 2026 filed with the Securities and Exchange Commission (the "SEC") on May 12, 2026, plus (ii) 509,293 shares of Common Stock issuable upon exercise of the Warrants directly held by the Redmile Funds, which due to the Beneficial Ownership Limitation is the maximum number of shares that could be issued upon exercise of those Warrants.

**(b)**
Item 5(b) of the Prior Schedule 13D is hereby amended and restated in its entirety as follows:

Redmile:
   (1) Sole Voting Power: 0
   (2) Shared Voting Power: 950,994
   (3) Sole Dispositive Power: 0
   (4) Shared Dispositive Power: 950,994

Jeremy C. Green:
   (1) Sole Voting Power: 0
   (2) Shared Voting Power: 950,994
   (3) Sole Dispositive Power: 0
   (4) Shared Dispositive Power: 950,994

RBI II:
   (1) Sole Voting Power: 0
   (2) Shared Voting Power: 651,924
   (3) Sole Dispositive Power: 0
   (4) Shared Dispositive Power: 651,924

Redmile Long Only:
   (1) Sole Voting Power: 0
   (2) Shared Voting Power: 576,148
   (3) Sole Dispositive Power: 0
   (4) Shared Dispositive Power: 576,148

**(c)**
—

### SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

**Reporting Person:** Redmile Group, LLC

**Signature:** /s/ Jeremy C. Green

**Name/Title:** Managing Member

**Date:** 05/14/2026

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

**Reporting Person:** Jeremy C. Green

**Signature:** /s/ Jeremy C. Green

**Name/Title:** Jeremy C. Green

**Date:** 05/14/2026

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

**Reporting Person:** Redmile Biopharma Investments II, L.P.

**Signature:** /s/ Jeremy C. Green

**Name/Title:** Managing Member of Redmile Biopharma Investments II (GP), LLC, general partner of Redmile Biopharma Investments II, L.P.

**Date:** 05/14/2026

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

**Reporting Person:** Redmile Strategic Long Only Trading Sub, Ltd.

**Signature:** /s/ Jeremy C. Green

**Name/Title:** Managing Member of Redmile Group, LLC, investment manager of Redmile Strategic Long Only Trading Sub, Ltd.

**Date:** 05/14/2026