Atara Biotherapeutics, Inc. (ATRA) Institutional Ownership

Institutions by Trading Activity

Ownership Statistics

13,446,875Shares Outstanding

1,086,107Shares held by institutions

$4,876,620Value of institutional holdings

14.81%Institutional ownership %

11.04%Shares Changed QoQ

41No. of institutional investors

Shares Owned by Institutions

Shares Purchased/Sold by Institutions

Ownership Summary

According to SEC filings for the period ending December 2025, Atara Biotherapeutics, Inc. (NASDAQ:ATRA) is held by 41 institutional firms.

The collective stake of institutional investors in Atara Biotherapeutics moved to 14.8% in December 2025, a shift up from the 14.0% reported for September 2025.
In percentage terms, this reflects as a holdings change of 11.04% quarter on quarter, and a decrease of 6.82% year over year.
Among the 41 institutional holders of Atara Biotherapeutics, 19 added to their stakes while 7 trimmed their positions and 15 held steady.
Collectively, institutional investors increased their stake in Atara Biotherapeutics to 1.99Mn shares as of December 2025, a change that is up by 198.05K shares quarter on quarter and down 377.14K shares year over year.
As of December 31, 2025, EcoR1 Capital, LLC held Atara Biotherapeutics's largest shareholding position with over 573.18K shares, representing 4.26% of total outstanding shares.
Among the most significant buyers of Atara Biotherapeutics during December 2025 were GLOBEFLEX CAPITAL L P (61.77K), MARSHALL WACE, LLP (32.84K), VANGUARD GROUP INC (22.50K), BRIDGEWAY CAPITAL MANAGEMENT, LLC (18.69K), Point72 Asset Management, L.P. (18.30K).
Leading sellers of Atara Biotherapeutics stock in December 2025 included MORGAN STANLEY (19.95K), UBS Group AG (15.87K), JANE STREET GROUP, LLC (8.07K), BlackRock, Inc. (2.73K), ACADIAN ASSET MANAGEMENT LLC (2.37K).
The top 10 institutional holders of Atara Biotherapeutics for the quarter ending December 2025 included EcoR1 Capital, LLC (573.18K), Redmile Group, LLC (441.70K), VANGUARD GROUP INC (225.94K), MARSHALL WACE, LLP (148.63K), GLOBEFLEX CAPITAL L P (77.22K), BlackRock, Inc. (67.11K), GEODE CAPITAL MANAGEMENT, LLC (62.38K), ACADIAN ASSET MANAGEMENT LLC (54.05K), STALEY CAPITAL ADVISERS INC (50.00K), BRIDGEWAY CAPITAL MANAGEMENT, LLC (32.69K).

41 Institutional Holders

1,086,107 Total Shares Held

Rows:

Download Data

Owner Name	Date	Shares Held	Change (QoQ)	Change (%)	Value (USD)
EcoR1 Capital, LLC	31 Dec, 2025	573,183	0	0.00%	$10,368,880.00
Redmile Group, LLC	31 Dec, 2025	441,701	0	0.00%	$7,990,371.00
VANGUARD GROUP INC	31 Dec, 2025	225,940	22,502	11.06%	$4,087,255.00
MARSHALL WACE, LLP	31 Dec, 2025	148,632	32,836	28.36%	$2,688,752.00
GLOBEFLEX CAPITAL L P	31 Dec, 2025	77,224	61,766	399.57%	$1,396,982.00
BlackRock, Inc.	31 Dec, 2025	67,108	-2,725	-3.90%	$1,213,984.00
GEODE CAPITAL MANAGEMENT, LLC	31 Dec, 2025	62,381	1,855	3.06%	$1,129,112.00
ACADIAN ASSET MANAGEMENT LLC	31 Dec, 2025	54,048	-2,368	-4.20%	$976.00
STALEY CAPITAL ADVISERS INC	31 Dec, 2025	50,000	0	0.00%	$904,500.00
BRIDGEWAY CAPITAL MANAGEMENT, LLC	31 Dec, 2025	32,691	18,691	133.51%	$591,380.00
RENAISSANCE TECHNOLOGIES LLC	31 Dec, 2025	30,040	11,104	58.64%	$543,424.00
STATE STREET CORP	31 Dec, 2025	26,453	1,200	4.75%	$478,535.00
Cambridge Investment Research Advisors, Inc.	31 Dec, 2025	22,864	5,755	33.64%	$414.00
Quadrature Capital Ltd	31 Dec, 2025	20,321	3,779	22.84%	$367,607.00
Point72 Asset Management, L.P.	31 Dec, 2025	18,296	18,296	0.00%	$330,975.00
FMR LLC	31 Dec, 2025	17,156	0	0.00%	$310,352.00
MORGAN STANLEY	31 Dec, 2025	15,991	-19,947	-55.50%	$289,276.00
CITADEL ADVISORS LLC	31 Dec, 2025	15,577	15,577	0.00%	$281,788.00
SUSQUEHANNA INTERNATIONAL GROUP, LLP	31 Dec, 2025	14,018	14,018	0.00%	$253,586.00
JANE STREET GROUP, LLC	31 Dec, 2025	13,990	-8,070	-36.58%	$253,080.00

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