How many institutional investors hold MASI?

5 tracked institutional investors disclosed a position in MASI (MASIMO CORP) in their most recent 13F filing.

Who is the largest institutional holder of MASI?

Izzy Englander, Millennium Management, holds the largest disclosed position in MASI, valued at $227M.

Where does this MASI ownership data come from?

SEC Form 13F-HR filings, accessed via EDGAR. 13F filings are disclosed quarterly with a 45-day reporting delay and cover U.S.-listed long equity positions only. This is not investment advice.

MASI — MASIMO CORP

Name: MASIMO CORP (MASI) — Institutional Ownership
Creator: InvestorLens
License: https://www.sec.gov/about/website-policies

Public company

For educational research only.InvestorLens analyzes public regulatory filings (SEC EDGAR, STOCK Act PTRs) that may be delayed by 45 days or more. Information shown is historical and is not financial, legal, or tax advice, nor a recommendation or solicitation to buy or sell any security. Always do your own research.

InvestorLens aggregates public filing data to show which tracked investors reported holdings in this stock. Dollar values represent reported position values, not market capitalization, and may be delayed up to 45 days. Not a recommendation.

Sourced from SEC EDGAR public filings

About MASIMO CORP (MASI)

MASIMO CORP (MASI) appears in the most recent 13F filings of 5 tracked institutional investors. The largest disclosed position is held by Izzy Englander (Millennium Management), valued at $227M. Across recent filings, tracked investors recorded 3 new positions, 1 increased, 2 reduced, and 1 exited. All data sourced from SEC 13F filings.

Tracked investors reporting MASI

Investor	Firm	Shares	Market value	% of portfolio	As of
Izzy Englander	Millennium Management	1.3M	$227.2M	0.09%	Mar 31, 2026
Andreas Halvorsen	Viking Global Investors	514.3K	$66.9M	0.18%	Dec 31, 2025
Ken Griffin	Citadel Advisors	332.8K	$59.2M	0.01%	Mar 31, 2026
George Soros	Soros Fund Management	100.8K	$17.9M	0.20%	Mar 31, 2026
Ray Dalio	Bridgewater Associates	1.9K	$337.8K	0.00%	Mar 31, 2026

Izzy EnglanderMar 31, 2026
Millennium Management
Shares
1.3M
Value
$227.2M
% Portfolio
0.09%
Andreas HalvorsenDec 31, 2025
Viking Global Investors
Shares
514.3K
Value
$66.9M
% Portfolio
0.18%
Ken GriffinMar 31, 2026
Citadel Advisors
Shares
332.8K
Value
$59.2M
% Portfolio
0.01%
George SorosMar 31, 2026
Soros Fund Management
Shares
100.8K
Value
$17.9M
% Portfolio
0.20%
Ray DalioMar 31, 2026
Bridgewater Associates
Shares
1.9K
Value
$337.8K
% Portfolio
0.00%

Recent activity

Investor	Action	Δ %	Current value	Filing date
Ken Griffin	Sold	-100.00%	$0	May 15, 2026
Andreas Halvorsen	New	—	$66.9M	Feb 17, 2026
George Soros	New	—	$17.9M	May 15, 2026
Ray Dalio	Increased	17.29%	$337.8K	May 15, 2026
Ken Griffin	Reduced	-49.33%	$6.7K	Feb 17, 2026
Ray Dalio	Reduced	-5.54%	$210	Feb 13, 2026
Ray Dalio	New	—	$252	Nov 13, 2025

Ken Griffin
Sold
$0(-100.00%)May 15, 2026
Andreas Halvorsen
New
$66.9MFeb 17, 2026
George Soros
New
$17.9MMay 15, 2026
Ray Dalio
Increased
$337.8K(17.29%)May 15, 2026
Ken Griffin
Reduced
$6.7K(-49.33%)Feb 17, 2026
Ray Dalio
Reduced
$210(-5.54%)Feb 13, 2026
Ray Dalio
New
$252Nov 13, 2025

Frequently asked questions

How many institutional investors hold MASI?: 5 tracked institutional investors disclosed a position in MASI (MASIMO CORP) in their most recent 13F filing.
Who is the largest institutional holder of MASI?: Izzy Englander, Millennium Management, holds the largest disclosed position in MASI, valued at $227M.
Did institutional ownership of MASI increase or decrease?: Across recent 13F filings, tracked investors recorded 3 new positions, 1 increased, 2 reduced, and 1 fully exited MASI.
Where does this MASI ownership data come from?: SEC Form 13F-HR filings, accessed via EDGAR. 13F filings are disclosed quarterly with a 45-day reporting delay and cover U.S.-listed long equity positions only. This is not investment advice.