13F Insight
DOSSIER · 13F Holders · Q1 2026Mega-capCrowded
MASI

MASIMO CORP

462 institutions still hold MASIMO CORP as of Q1 2026. Tracked across SEC 13F-HR filings, with insider and 13D/G activity surfaced alongside.

CUSIP 574795100·462 13F holders·last filed Mar 31, 2026
Market cap
—
▲ 6.6%
vs prior quarter
13F value held
$6.2B
63.0% inst. owned
of float
Holders
462
+75 QoQ
filers reporting
Activity
+10 / −57
+957 added · −821 reduced
this quarter
Concentration
13.42%
BlackRock, Inc. #1
top holder share
AI Holders Summary · Q1 2026

462 institutions reported MASI in Q1 2026. BlackRock, Inc. leads at 13.4% of the visible book. +75 net new institutions vs prior quarter — accumulation reading.

Top holders

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

#HolderValueShares% port.Quarter
01
BlackRock, Inc.
CIK 0002012383
$826M4.6M0.01%Q1 202602
Politan Capital Management LP
CIK 0001885245
$597M4.6M71.01%Q4 202503
Pentwater Capital Management LP
CIK 0001425851
$565M3.2M2.93%Q1 202604
BARCLAYS PLC
CIK 0000312069
$488M2.7M0.12%Q1 202605
HBK INVESTMENTS L P
CIK 0001011443
$458M2.6M4.65%Q1 202606
MASSACHUSETTS FINANCIAL SERVICES CO /MA/
CIK 0000912938
$417M2.3M0.14%Q1 202607
VANGUARD CAPITAL MANAGEMENT LLC
CIK 0002100119· Index
$365M2.1M0.01%Q1 202608
Vanguard Portfolio Management
CIK 0002100121
$357M2.0M0.02%Q1 202609
FMR LLC
CIK 0000315066
$258M1.5M0.01%Q1 202610
STATE STREET CORP
CIK 0000093751
$256M1.4M0.01%Q1 202611
MILLENNIUM MANAGEMENT LLC
CIK 0001273087
$227M1.3M0.09%Q1 202612
NAYA CAPITAL MANAGEMENT UK LTD
CIK 0001665012
$203M1.6M15.28%Q4 202513
GOLDMAN SACHS GROUP INC
CIK 0000886982
$175M984K0.02%Q1 202614
GEODE CAPITAL MANAGEMENT, LLC
CIK 0001214717· Index
$170M957K0.01%Q1 202615
Alyeska Investment Group, L.P.
CIK 0001453072
$164M1.3M0.46%Q4 202516
BALYASNY ASSET MANAGEMENT L.P.
CIK 0001218710
$152M856K0.20%Q1 202617
AQR CAPITAL MANAGEMENT LLC
CIK 0001167557
$147M832K0.07%Q1 202618
MORGAN STANLEY
CIK 0000895421
$134M752K0.01%Q1 202619
JPMORGAN CHASE & CO
CIK 0000019617
$102M573K0.01%Q1 202620
CITIGROUP INC
CIK 0000831001
$95M533K0.04%Q1 2026
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