DOSSIER · 13F Holders · Q1 2026High-convictionMulti-bagger
ATRA

ATARA BIOTHERAPEUTICS INC

37 institutions still hold ATARA BIOTHERAPEUTICS INC as of Q1 2026. Tracked across SEC 13F-HR filings, with insider and 13D/G activity surfaced alongside.

CUSIP 046513206·37 13F holders·last filed Mar 31, 2026
Market cap
8.8%
vs prior quarter
13F value held
$15M
52.0% inst. owned
of float
Holders
37
-42 QoQ
filers reporting
Activity
+31 / −6
+899 added · −709 reduced
this quarter
Concentration
22.43%
ADAGE CAPITAL PARTNERS GP, L.L.C. #1
top holder share
AI Holders Summary · Q1 2026

37 institutions reported ATRA in Q1 2026. ADAGE CAPITAL PARTNERS GP, L.L.C. leads at 22.4% of the visible book. -42 net institutions QoQ — distribution reading.

Top holders

Sorted by position value. Source: SEC EDGAR 13F-HR filings.

#HolderValueShares% port.Quarter
01
ADAGE CAPITAL PARTNERS GP, L.L.C.
CIK 0001165408
$3M700K0.01%Q1 2026
02
MARSHALL WACE, LLP
CIK 0001318757
$3M149K0.00%Q4 2025
03
Redmile Group, LLC
CIK 0001425738
$2M442K0.14%Q1 2026
04
MACKENZIE FINANCIAL CORP
CIK 0000919859
$1M314K0.00%Q1 2026
05
VANGUARD CAPITAL MANAGEMENT LLC
CIK 0002100119· Index
$1M218K0.00%Q1 2026
06
Point72 Asset Management, L.P.
CIK 0001603466
$918,869194K0.00%Q1 2026
07
EcoR1 Capital, LLC
CIK 0001587114
$471,075100K0.02%Q1 2026
08
BlackRock, Inc.
CIK 0002012383
$373,77379K0.00%Q1 2026
09
Quadrature Capital Ltd
CIK 0001651424
$367,60720K0.00%Q4 2025
10
GEODE CAPITAL MANAGEMENT, LLC
CIK 0001214717· Index
$313,04566K0.00%Q1 2026
11
CITADEL ADVISORS LLC
CIK 0001423053
$281,78816K0.00%Q4 2025
12
UBS Group AG
CIK 0001610520
$236,83150K0.00%Q1 2026
13
STALEY CAPITAL ADVISERS INC
CIK 0001106565
$236,50050K0.01%Q1 2026
14
MILLENNIUM MANAGEMENT LLC
CIK 0001273087
$225,56948K0.00%Q1 2026
15
JANE STREET GROUP, LLC
CIK 0001595888· Market maker
$160,20634K0.00%Q1 2026
16
VANGUARD FIDUCIARY TRUST CO
CIK 0000933478· Index
$159,02734K0.00%Q1 2026
17
BRIDGEWAY CAPITAL MANAGEMENT, LLC
CIK 0001107261
$154,62833K0.00%Q1 2026
18
STATE STREET CORP
CIK 0000093751
$125,12326K0.00%Q1 2026
19
FMR LLC
CIK 0000315066
$76,80616K0.00%Q1 2026
20
NORTHERN TRUST CORP
CIK 0000073124· Index
$58,36812K0.00%Q1 2026
Page 1 of 2
17 more holders available. Log in →