AI Holders Summary · Q2 2026

37 institutions reported ATRA in Q2 2026. EcoR1 Capital, LLC leads at 43.3% 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

MACKENZIE FINANCIAL CORP

CIK 0000919859

$3M233K0.00%Q2 2026 05

Redmile Group, LLC

CIK 0001425738

$2M442K0.14%Q1 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

$863K75K0.00%Q2 2026 09

ACADIAN ASSET MANAGEMENT LLC

CIK 0000916542

$617K131K0.00%Q1 2026 10

STALEY CAPITAL ADVISERS INC

CIK 0001106565

$574K50K0.02%Q2 2026 11

VANGUARD FIDUCIARY TRUST CO

CIK 0000933478· Index

$494K43K0.00%Q2 2026 12

STATE STREET CORP

CIK 0000093751

$304K26K0.00%Q2 2026 13

NORTHERN TRUST CORP

CIK 0000073124· Index

$190K17K0.00%Q2 2026 14

FMR LLC

CIK 0000315066

$186K16K0.00%Q2 2026 15

XTX Topco Ltd

CIK 0001828301

$176K15K0.00%Q2 2026 16

BRIDGEWAY CAPITAL MANAGEMENT, LLC

CIK 0001107261

$161K14K0.00%Q2 2026 17

JANE STREET GROUP, LLC

CIK 0001595888· Market maker

$160K34K0.00%Q1 2026 18

MILLENNIUM MANAGEMENT LLC

CIK 0001273087

$146K13K0.00%Q2 2026 19

CITADEL ADVISORS LLC

CIK 0001423053

$117K10K0.00%Q2 2026 20

MORGAN STANLEY

CIK 0000895421

$105K9K0.00%Q2 2026

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