AI Holders Summary · Q1 2026

403 institutions reported MASI in Q1 2026. BlackRock, Inc. leads at 13.4% of the visible book.

Top holders

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

Hide index funds / market makers / custodians(3 on this page)

#HolderValueShares% port.Quarter

BlackRock, Inc.

CIK 0002012383

$826M4.6M0.01%Q1 2026 02

Politan Capital Management LP

CIK 0001885245

$597M4.6M71.01%Q4 2025 03

Pentwater Capital Management LP

CIK 0001425851

$565M3.2M2.93%Q1 2026 04

BARCLAYS PLC

CIK 0000312069

$488M2.7M0.12%Q1 2026 05

HBK INVESTMENTS L P

CIK 0001011443

$458M2.6M4.65%Q1 2026 06

MASSACHUSETTS FINANCIAL SERVICES CO /MA/

CIK 0000912938

$417M2.3M0.14%Q1 2026 07

VANGUARD CAPITAL MANAGEMENT LLC

CIK 0002100119· Index

$365M2.1M0.01%Q1 2026 08

Vanguard Portfolio Management

CIK 0002100121· Index

$357M2.0M0.02%Q1 2026 09

FMR LLC

CIK 0000315066

$258M1.5M0.01%Q1 2026 10

STATE STREET CORP

CIK 0000093751

$256M1.4M0.01%Q1 2026 11

MILLENNIUM MANAGEMENT LLC

CIK 0001273087

$227M1.3M0.09%Q1 2026 12

NAYA CAPITAL MANAGEMENT UK LTD

CIK 0001665012

$203M1.6M15.28%Q4 2025 13

GOLDMAN SACHS GROUP INC

CIK 0000886982

$175M984K0.02%Q1 2026 14

GEODE CAPITAL MANAGEMENT, LLC

CIK 0001214717· Index

$170M957K0.01%Q1 2026 15

Alyeska Investment Group, L.P.

CIK 0001453072

$164M1.3M0.46%Q4 2025 16

BALYASNY ASSET MANAGEMENT L.P.

CIK 0001218710

$152M856K0.20%Q1 2026 17

AQR CAPITAL MANAGEMENT LLC

CIK 0001167557

$147M832K0.07%Q1 2026 18

MORGAN STANLEY

CIK 0000895421

$134M752K0.01%Q1 2026 19

JPMORGAN CHASE & CO

CIK 0000019617

$102M573K0.01%Q1 2026 20

CITIGROUP INC

CIK 0000831001

$95M533K0.04%Q1 2026

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