AI Holders Summary · Q2 2026

38 institutions reported ATRA in Q2 2026. EcoR1 Capital, LLC leads at 45.5% of the visible book.

Top holders

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

Hide index funds / market makers / custodians(5 on this page)

#HolderValueShares% port.Quarter

EcoR1 Capital, LLC

CIK 0001587114

$18M1.6M0.87%Q2 2026 02

ADAGE CAPITAL PARTNERS GP, L.L.C.

CIK 0001165408

$10M850K0.01%Q2 2026 03

VANGUARD CAPITAL MANAGEMENT LLC

CIK 0002100119· Index

$3M247K0.00%Q2 2026 04

Redmile Group, LLC

CIK 0001425738

$2M442K0.14%Q1 2026 05

MACKENZIE FINANCIAL CORP

CIK 0000919859

$2M177K0.00%Q3 2026 06

BlackRock, Inc.

CIK 0002012383

$970K84K0.00%Q2 2026 07

Point72 Asset Management, L.P.

CIK 0001603466

$919K194K0.00%Q1 2026 08

GEODE CAPITAL MANAGEMENT, LLC

CIK 0001214717· Index

$688K81K0.00%Q3 2026 09

VANGUARD FIDUCIARY TRUST CO

CIK 0000933478· Index

$494K43K0.00%Q2 2026 10

STALEY CAPITAL ADVISERS INC

CIK 0001106565

$425K50K0.02%Q3 2026 11

STATE STREET CORP

CIK 0000093751

$304K26K0.00%Q2 2026 12

NORTHERN TRUST CORP

CIK 0000073124· Index

$190K17K0.00%Q2 2026 13

UBS Group AG

CIK 0001610520

$176K21K0.00%Q3 2026 14

XTX Topco Ltd

CIK 0001828301

$176K15K0.00%Q2 2026 15

BRIDGEWAY CAPITAL MANAGEMENT, LLC

CIK 0001107261

$161K14K0.00%Q2 2026 16

JANE STREET GROUP, LLC

CIK 0001595888· Market maker

$160K34K0.00%Q1 2026 17

MILLENNIUM MANAGEMENT LLC

CIK 0001273087

$146K13K0.00%Q2 2026 18

FMR LLC

CIK 0000315066

$138K16K0.00%Q3 2026 19

CITADEL ADVISORS LLC

CIK 0001423053

$117K10K0.00%Q2 2026 20

MORGAN STANLEY

CIK 0000895421

$105K9K0.00%Q2 2026

Page 1 of 2

18 more holders available. Log in →