Atara Biotherapeutics, Inc. - Common Stock, par value $0.0001 per share (ATRA)

Q: What does CUSIP 046513107 represent in this 13F holders report?

CUSIP 046513107 is the security identifier for ATRA - Atara Biotherapeutics, Inc. - Common Stock, par value $0.0001 per share used to aggregate holder disclosures.

Q: How many institutions held ATRA - Atara Biotherapeutics, Inc. - Common Stock, par value $0.0001 per share in Q1 2026?

1 institutional investor reported ATRA - Atara Biotherapeutics, Inc. - Common Stock, par value $0.0001 per share for Q1 2026. Use the holders table for investor-level position and value details.

CUSIP: 046513107

Q1 2026 13F Holders as of 31 Mar 2026

Type / Class: Equity / Common Stock, par value $0.0001 per share
Shares outstanding: 9,606,000
Total 13F shares: 28
Share change: 0
Total reported value: $132
Price per share: $4.71
Number of holders: 1

Quarterly Holders Quick Answers

What is CUSIP 046513107?
CUSIP 046513107 identifies ATRA - Atara Biotherapeutics, Inc. - Common Stock, par value $0.0001 per share in SEC institutional holdings data.

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Previous quarter: Q4 2025

Recent filing periods for CUSIP 046513107:

Q1 2026 Q4 2025 Q3 2025 Q1 2025 Q4 2024 Q3 2024 Q2 2024 Q1 2024

Top shareholders of ATRA - Atara Biotherapeutics, Inc. - Common Stock, par value $0.0001 per share (13F + 13D/G + 3/4/5)

Grouped by holder across the latest SEC ownership disclosures. Ownership % is shown only when it is directly reported or safely comparable across share classes.

Methodology: rows are grouped by holder and ranked by the holder's primary source value. — indicates unavailable or non-comparable values; "mixed-class rows" means the latest filing spans non-comparable classes.

Holder	Source	Role / Reporting	Ownership %	Shares	Holdings Value	12M Net Δ	As of	Details
Redmile Group, LLC	13D/G 3/4/5 13F	Director · Company	9.9%	751,223	$10,764,875	+$659,400	12 Nov 2025	13D/G 3/4/5 13F
Adiumentum Capital Fund I LP	3/4/5 13D/G	Director, Other*, 10%+ Owner	20% from 13D/G	1,586,588 mixed-class rows	$10,487,308	—	16 May 2025	3/4/5 13D/G
EcoR1 Capital, LLC	13F 13D/G	Company	9.9% from 13D/G	573,183	$10,368,880	—	31 Dec 2025	13F 13D/G
VANGUARD GROUP INC	13F	Company	2.8%	225,940	$4,087,255	—	31 Dec 2025	13F
MARSHALL WACE, LLP	13F	Company	1.8%	148,632	$2,688,752	—	31 Dec 2025	13F
GLOBEFLEX CAPITAL L P	13F	Company	0.94%	77,224	$1,396,982	—	31 Dec 2025	13F
BlackRock, Inc.	13F	Company	0.82%	67,108	$1,213,984	—	31 Dec 2025	13F
GEODE CAPITAL MANAGEMENT, LLC	13F	Company	0.76%	62,381	$1,129,112	—	31 Dec 2025	13F
MACKENZIE FINANCIAL CORP	13F	Company	0.72%	58,668	$1,046,920	—	31 Dec 2025	13F
ACADIAN ASSET MANAGEMENT LLC	13F	Company	0.66%	54,048	$976,000	—	31 Dec 2025	13F
STALEY CAPITAL ADVISERS INC	13F	Company	0.61%	50,000	$904,500	—	31 Dec 2025	13F
AnhCo Nguyen	3/4/5	President and CEO, Director	1.7%	143,078	$636,697	-$88,035	09 Mar 2026	3/4/5
BRIDGEWAY CAPITAL MANAGEMENT, LLC	13F	Company	0.4%	32,691	$591,380	—	31 Dec 2025	13F
Pascal Touchon	3/4/5	Director	0.95%	77,955	$589,339	—	10 Jun 2025	3/4/5
RENAISSANCE TECHNOLOGIES LLC	13F	Company	0.37%	30,040	$543,424	—	31 Dec 2025	13F
STATE STREET CORP	13F	Company	0.32%	26,453	$478,535	—	31 Dec 2025	13F
Cambridge Investment Research Advisors, Inc.	13F	Company	0.28%	22,864	$414,000	—	31 Dec 2025	13F
Eric J. Hyllengren	3/4/5	Former EVP, CFO & COO	— mixed-class rows	58,887 mixed-class rows	$393,448	—	31 Mar 2025	3/4/5
Quadrature Capital Ltd	13F	Company	0.25%	20,321	$367,607	—	31 Dec 2025	13F
Point72 Asset Management, L.P.	13F	Company	0.22%	18,296	$330,975	—	31 Dec 2025	13F
FMR LLC	13F	Company	0.21%	17,156	$310,352	—	31 Dec 2025	13F
MORGAN STANLEY	13F	Company	0.2%	15,991	$289,276	—	31 Dec 2025	13F
CITADEL ADVISORS LLC	13F	Company	0.19%	15,577	$281,788	—	31 Dec 2025	13F
SUSQUEHANNA INTERNATIONAL GROUP, LLP	13F	Company	0.17%	14,018	$253,586	—	31 Dec 2025	13F
JANE STREET GROUP, LLC	13F	Company	0.17%	13,990	$253,080	—	31 Dec 2025	13F
Carol Giltner Gallagher	3/4/5	Director	0.4%	33,012	$249,570	—	10 Jun 2025	3/4/5
Yanina Grant-Huerta	3/4/5	Chief Accounting Officer	0.64%	52,050	$231,622	-$55,488	09 Mar 2026	3/4/5
NORTHERN TRUST CORP	13F	Company	0.15%	12,340	$223,231	—	31 Dec 2025	13F
Walleye Capital LLC	13F	Company	0.15%	12,169	$220,137	—	31 Dec 2025	13F
Eric Dobmeier	3/4/5	Director	— mixed-class rows	642,825 mixed-class rows	$219,133	—	10 Nov 2023	3/4/5
Connor, Clark & Lunn Investment Management Ltd.	13F	Company	0.13%	10,446	$188,968	—	31 Dec 2025	13F
BANK OF AMERICA CORP /DE/	13F	Company	0.13%	10,387	$187,901	—	31 Dec 2025	13F
DIMENSIONAL FUND ADVISORS LP	13F	Company	0.12%	10,028	$181,406	—	31 Dec 2025	13F
Amar Murugan	3/4/5	EVP, Chief Legal Officer	— class O/S missing	26,827	$177,890	—	16 Aug 2024	3/4/5
William K. Heiden	3/4/5	Director	0.27%	22,188	$167,741	—	10 Jun 2025	3/4/5
Matthew K. Fust	3/4/5	Director	0.22%	18,188	$137,501	—	10 Jun 2025	3/4/5
Maria Grazia Roncarolo	3/4/5	Director	0.21%	17,368	$131,302	—	10 Jun 2025	3/4/5
Jill Henrich	3/4/5	EVP, Chief Regulatory Officer	— class O/S missing	18,679	$130,697	—	03 Mar 2025	3/4/5
Ameet Mallik	3/4/5	Director	0.21%	16,928	$127,975	—	10 Jun 2025	3/4/5
Jakob Dupont	3/4/5	EVP, Head of R&D	— mixed-class rows	608,781 mixed-class rows	$113,119	—	02 Mar 2023	3/4/5
Charlene A. Banard	3/4/5	EVP, Chief Technical Officer	— class O/S missing	276,010	$107,368	—	16 May 2023	3/4/5
Utpal Koppikar	3/4/5	Chief Financial Officer	— class O/S missing	181,978	$70,789	—	02 Mar 2023	3/4/5
Kristin Yarema	3/4/5	Chief Commercial Officer	— mixed-class rows	257,007 mixed-class rows	$66,680	—	01 Mar 2022	3/4/5
Manher Joshi	3/4/5	EVP, Chief Medical Officer	— class O/S missing	171,284	$66,629	—	16 Nov 2023	3/4/5
Beth C. Seidenberg	3/4/5	Director	— mixed-class rows	195,386 mixed-class rows	$45,080	—	31 May 2023	3/4/5
Joe Newell	3/4/5	Chief Operations Officer	— mixed-class rows	123,014 mixed-class rows	$43,995	—	16 Nov 2021	3/4/5
Tower Research Capital LLC (TRC)	13F	Company	0.02%	1,737	$31,422	—	31 Dec 2025	13F
SBI Securities Co., Ltd.	13F	Company	0.02%	1,404	$25,398	—	31 Dec 2025	13F
UBS Group AG	13F	Company	0.02%	1,397	$25,271	—	31 Dec 2025	13F
Roy D. Baynes	3/4/5	Director	— mixed-class rows	75,000 mixed-class rows	$16,922	—	23 Jun 2022	3/4/5

Institutional Holders of Atara Biotherapeutics, Inc. - Common Stock, par value $0.0001 per share (ATRA) as of Q1 2026

As of 31 Mar 2026, Atara Biotherapeutics, Inc. - Common Stock, par value $0.0001 per share (ATRA) was held by 1 institutional shareholder that filed Form 13F with the SEC. Together, they reported ownership of 28 shares. The largest 1 holders included PlanVest Financial, Inc. This page lists 1 institutional shareholders reporting positions in this security for the Q1 2026 filing period.

Investor	Option	Weight %	Change %	Value $	* Price	Shares	Share Change	Activity	Report Period

Compare Q1 2026 vs Q4 2025 Across Filers

Q4 2025 holders

Q1 2026 holders

Holder diff

Investor	Q4 2025 Shares	Q1 2026 Shares	Share Diff	Share Chg %	Q4 2025 Value $	Q1 2026 Value $	Value Diff $	Value Chg %

Trend: ostatnie 8 kwartałów (+ wybrane okresy porównania).

Quarterly Holders Trend

Quarterly Value Trend

Quarterly Shares Trend

* Reported Price is the price of the security as of the portfolio date. This value is significant in that it is the last known price at which the security was still held.
An asterisk sign (*) next to the price indicates that the price is likely invalid.