Comparable stake leader
BlackRock, Inc.
SEC ownership of MASIMO CORP
Top holders, 13D/G large-stake signals, insider positions, and transaction flow tied to CIK 0000937556.
Disclosed value leader
BlackRock, Inc.
Comparable rows
50/50
Latest evidence
31 Mar 2026
- Public ticker
- MASI on Nasdaq
- Parsed ownership sources
- 13F, 13D/G, and 3/4/5
- Largest SEC-reported holder
- BlackRock, Inc.
- Latest 13D/G holder
- BlackRock, Inc.
- Latest parsed ownership date
- 31 Mar 2026
- Issuer CIK
- 0000937556
- Issuer location
- Irvine, CA
Ownership snapshot
CIK-linked ownership evidence from parsed SEC filings.
2 signals
Issuer
Names, identifiers, and filing context for this profile.
2 identity fields
Ownership snapshot
Top shareholders of MASIMO CORP (13F + 13D/G + 3/4/5)
Grouped by holder across the latest SEC ownership disclosures. Start with comparable ownership when available, then verify the linked 13F, 13D/G, or 3/4/5 evidence.
Comparable stake leader
BlackRock, Inc.
Disclosed value leader
BlackRock, Inc.
Comparable rows
50/50
Latest evidence
31 Mar 2026
13F
13D/G
3/4/5
Lead comparable stake: 7.9%
13D/G row: BlackRock, Inc.
Showing 1-8 of 50 holder rows.
Quick read
BlackRock, Inc. leads the comparable SEC ownership view at 7.9%.
50 of 50 rows have a safely comparable ownership percentage. Use this as a filing-backed starting point, then open the detailed table for source links, reporting role, position value, share count, and filing date.
Open SEC evidence
Opens BlackRock, Inc.'s linked filing trail.
Comparable ownership
Top 5
BlackRock, Inc.
7.9%
Joe E. Kiani
6.5%
Politan Capital Management LP
6.2%
Pentwater Capital Management LP
6.1%
BARCLAYS PLC
5.5%
Ownership % is shown only when SEC disclosures are safely comparable across share classes.
Detailed SEC evidence table Showing 1-8 of 50 holder rows
| Holder | Evidence | Ownership % | Position | 12M Net Δ | As of |
|---|---|---|---|---|---|
| BlackRock, Inc. |
13F
13D/G
Company
|
7.9%
from 13D/G
|
$826,131,120
4,644,578 shares
|
— | 31 Mar 2026 |
| Joe E. Kiani |
13D/G
3/4/5
Joe Kiani · CEO and Chairman of the Board, Director
|
6.5%
|
$652,671,750
3,657,039 shares
|
-$401,127,387 | 31 Mar 2026 |
| Politan Capital Management LP |
13F
13D/G
3/4/5
Company · Quentin Koffey · Director by deputization
|
6.2%
from 13D/G
|
$816,360,690
4,589,648 shares
|
— | 31 Mar 2026 |
| Pentwater Capital Management LP |
13D/G
13F
Company
|
6.1%
|
$566,820,720
3,176,000 shares
|
$0 | 31 Mar 2026 |
| BARCLAYS PLC |
13D/G
13F
Company
|
5.5%
|
$516,181,999
2,892,262 shares
|
$0 | 31 Mar 2026 |
| FMR LLC |
13D/G
13F
Company
|
4.5%
|
$317,340,559
2,349,975 shares
|
-$767,176,959 | 27 Feb 2026 |
| BlackRock Portfolio Management LLC |
13D/G
|
0.2%
|
$20,787,845
116,871 shares
|
-$759,403,692 | 31 Mar 2026 |
| Craig B. Reynolds |
3/4/5
Director
|
0.04%
|
$3,064,557
18,371 shares
mixed-class rows
|
— | 29 Apr 2025 |
How to read this table
Rows are grouped by holder and ranked first by SEC-reported ownership % when it is safely comparable, then by disclosed holdings value. — indicates unavailable or non-comparable values; "mixed-class rows" means the latest filing spans non-comparable classes.
Forms 3/4/5 flow
Insider trading overview
Net insider flow leans to selling over the last 12 months. Net value: -$2,087,070.
Buys
$468,500
Insiders: 2
Sells
$2,555,570
Insiders: 1
Net
-$2,087,070
Shares: -15,480
Window
Last 12 months
4 rolling buckets
Buy value
Sell value
Shares: 3,200
Shares: 18,680
| Window (months) | Buy shares | Sell shares | Buy value | Sell value | Net value |
|---|---|---|---|---|---|
| 0-3 | 0 | 0 | $0 | $0 | $0 |
| 3-6 | 0 | 18,680 | $0 | $2,555,570 | -$2,555,570 |
| 6-9 | 0 | 0 | $0 | $0 | $0 |
| 9-12 | 3,200 | 0 | $468,500 | $0 | +$468,500 |
Reporting owners
Insider holders from Forms 3/4/5
Showing 1-20 of 28 reporting-owner rows connected to MASIMO CORP. Open a relationship link for the CIK-to-CIK filing trail.
Rows
28
Largest Forms 3/4/5 holder
Politan Capital Management LP
Net 12M change
-$2,087,070
Latest report
23 Apr 2026
| Name | Relationship | Holdings Value | Past Year Net Change | Change % | Valuation | Report Date |
|---|---|---|---|---|---|---|
| Politan Capital Management LP | Director by deputization | $744,390,354 | Mixed | 11 Mar 2026 | ||
| Joe E. Kiani | CEO and Chairman of the Board, Director | $76,686,577 | Mixed | 08 Aug 2024 | ||
| Thomas Samuel McClenahan | Evp, Gen Counsel & Corp Sec | $9,474,979 | Mixed | 28 Feb 2024 | ||
| Anand Sampath | EVP, Operations | $5,649,123 | -$2,555,570 | -31% | Filing P/S | 06 Mar 2026 |
| Blair Tripodi | COO, Consumer Division | $4,885,319 | Mixed | 23 Sep 2025 | ||
| Bilal Muhsin | Chief Operating Officer | $4,570,915 | Mixed | 12 May 2025 | ||
| Tao Levy | EVP, Bus Dev | $4,334,641 | Mixed | 13 Nov 2024 | ||
| Micah W. Young | EVP & Chief Financial Officer | $4,064,887 | Mixed | 11 Mar 2026 | ||
| Craig B. Reynolds | Director | $3,064,557 | Mixed | 29 Apr 2025 | ||
| Kevin P. Duffy | President, Consumer | $2,988,646 | Mixed | 11 Apr 2022 | ||
| Catherine M. Szyman | CEO, Director | $2,470,965 | Mixed | 11 Mar 2026 | ||
| Michelle Brennan | Director, Chairman of the Board | $1,519,543 | +$30,560 | +2.1% | Median | 23 Apr 2026 |
| Thomas Harkin | Director | $1,042,301 | Mixed | 27 May 2021 | ||
| Robert A. Chapek | Director | $857,996 | Mixed | 29 Apr 2025 | ||
| William R. Jellison | Director | $740,486 | +$437,940 | +145% | Mixed | 11 Aug 2025 |
| Julie Ann Shimer | Director | $697,609 | Mixed | 26 May 2023 | ||
| H. Michael Cohen | Director | $604,753 | Mixed | 26 May 2023 | ||
| Timothy J. Scannell | Director | $495,748 | Mixed | 23 Apr 2026 | ||
| Wendy E. Lane | Director | $495,748 | Mixed | 23 Apr 2026 | ||
| Omar Ahmed | CTIO & EVP of Engineering | $467,029 | Mixed | 13 Nov 2025 |
Recent insider transactions for MASIMO CORP
Showing up to 300 recent insider transactions from the last 12 months.
| Insider | Symbol | Class | Transaction | % | SEC-reported value | SEC-reported price | Shares | Shares owned | Date | Ownership |
|---|---|---|---|---|---|---|---|---|---|---|
| Timothy J. Scannell | MASI | Common Stock | Options Exercise | 88.6% | 1,225 | 2,608 | 29 Apr 2026 | Direct | ||
| Timothy J. Scannell | MASI | Restricted Stock Units | Options Exercise | -100% | -1,225 | 0 | 29 Apr 2026 | Direct | ||
| Wendy E. Lane | MASI | Common Stock | Options Exercise | 88.6% | 1,225 | 2,608 | 29 Apr 2026 | Direct | ||
| Wendy E. Lane | MASI | Restricted Stock Units | Options Exercise | -100% | -1,225 | 0 | 29 Apr 2026 | Direct | ||
| Michelle Brennan | MASI | Common Stock | Options Exercise | 16.7% | 1,225 | 8,543 | 29 Apr 2026 | Direct | ||
| Michelle Brennan | MASI | Restricted Stock Units | Options Exercise | -100% | -1,225 | 0 | 29 Apr 2026 | Direct | ||
| Timothy J. Scannell | MASI | Restricted Stock Units | Award | 100% | 1,119 | 2,238 | 23 Apr 2026 | Direct | ||
| Wendy E. Lane | MASI | Restricted Stock Units | Award | 100% | 1,119 | 2,238 | 23 Apr 2026 | Direct | ||
| Michelle Brennan | MASI | Restricted Stock Units | Award | 100% | 1,119 | 2,238 | 23 Apr 2026 | Direct | ||
| Elisabeth A. Hellmann | MASI | Common Stock | Tax liability | -36.1% | -121 | 214 | 21 Apr 2026 | Direct | ||
| Elisabeth A. Hellmann | MASI | Common Stock | Options Exercise | 335 | 335 | 21 Apr 2026 | Direct | |||
| Elisabeth A. Hellmann | MASI | Restricted Stock Units | Options Exercise | -25% | -335 | 1,005 | 21 Apr 2026 | Direct | ||
| Politan Capital Management LP | MASI | Forward Sale Contract (obligation to sell) | Other | 130,869 | 130,869 | 12 Mar 2026 | See footnotes | |||
| Catherine M. Szyman | MASI | Common Stock | Tax liability | -12.3% | -1,069 | 7,605 | 11 Mar 2026 | Direct | ||
| Catherine M. Szyman | MASI | Common Stock | Options Exercise | 32% | 2,101 | 8,674 | 11 Mar 2026 | Direct | ||
| Catherine M. Szyman | MASI | Restricted Stock Units | Options Exercise | -25% | -2,101 | 6,306 | 11 Mar 2026 | Direct | ||
| Micah W. Young | MASI | Common Stock | Tax liability | -1.8% | -471 | 25,656 | 11 Mar 2026 | Direct | ||
| Micah W. Young | MASI | Common Stock | Options Exercise | 3.46% | 873 | 26,127 | 11 Mar 2026 | Direct | ||
| Micah W. Young | MASI | Restricted Stock Units | Options Exercise | -25% | -873 | 2,622 | 11 Mar 2026 | Direct | ||
| Politan Capital Management LP | MASI | Forward Sale Contract (obligation to sell) | Other | 142,681 | 142,681 | 11 Mar 2026 | See footnotes | |||
| Greg Allen Meehan | MASI | Restricted Stock Units | Award | 8,550 | 8,550 | 06 Mar 2026 | Direct | |||
| Tim Benner | MASI | Restricted Stock Units | Award | 6,128 | 6,128 | 06 Mar 2026 | Direct | |||
| Elisabeth A. Hellmann | MASI | Restricted Stock Units | Award | 5,985 | 5,985 | 06 Mar 2026 | Direct | |||
| Anand Sampath | MASI | Restricted Stock Units | Award | 6,840 | 6,840 | 06 Mar 2026 | Direct | |||
| Charles Dadswell | MASI | Restricted Stock Units | Award | 10,261 | 10,261 | 06 Mar 2026 | Direct | |||
| Micah W. Young | MASI | Restricted Stock Units | Award | 17,671 | 17,671 | 06 Mar 2026 | Direct | |||
| Catherine M. Szyman | MASI | Restricted Stock Units | Award | 39,904 | 39,904 | 06 Mar 2026 | Direct | |||
| Micah W. Young | MASI | Common Stock | Tax liability | -24.3% | -8,093 | 25,254 | 27 Feb 2026 | Direct | ||
| Micah W. Young | MASI | Common Stock | Award | 81.8% | 15,000 | 33,347 | 27 Feb 2026 | Direct | ||
| Micah W. Young | MASI | Restricted Stock Units | Options Exercise | -100% | -15,000 | 0 | 27 Feb 2026 | Direct | ||
| Micah W. Young | MASI | Common Stock | Tax liability | -5.77% | -1,123 | 18,347 | 26 Feb 2026 | Direct | ||
| Micah W. Young | MASI | Common Stock | Award | 11.7% | 2,034 | 19,470 | 26 Feb 2026 | Direct | ||
| Catherine M. Szyman | MASI | Common Stock | Tax liability | -41% | -4,568 | 6,573 | 12 Feb 2026 | Direct | ||
| Catherine M. Szyman | MASI | Common Stock | Options Exercise | 11,141 | 11,141 | 12 Feb 2026 | Direct | |||
| Catherine M. Szyman | MASI | Restricted Stock Units | Options Exercise | -33.3% | -11,141 | 22,283 | 12 Feb 2026 | Direct | ||
| Anand Sampath | MASI | Common Stock | Sale | -31.4% | $2,555,570 | $136.81 | -18,680 | 40,909 | 28 Jan 2026 | Direct |
| Anand Sampath | MASI | Common Stock | Options Exercise | 101.4% | 30,000 | 59,589 | 28 Jan 2026 | Direct | ||
| Anand Sampath | MASI | Non-Qualified Stock Option (Right to Buy) | Options Exercise | -100% | -30,000 | 0 | 28 Jan 2026 | Direct | ||
| Omar Ahmed | MASI | Common Stock | Tax liability | -23% | -974 | 3,268 | 13 Nov 2025 | Direct | ||
| Omar Ahmed | MASI | Common Stock | Options Exercise | 139.9% | 2,474 | 4,242 | 13 Nov 2025 | Direct | ||
| Omar Ahmed | MASI | Restricted Stock Units | Options Exercise | -100% | -2,474 | 0 | 13 Nov 2025 | Direct | ||
| Blair Tripodi | MASI | Common Stock | Tax liability | -36.9% | -8,078 | 13,818 | 23 Sep 2025 | Direct | ||
| Blair Tripodi | MASI | Common Stock | Options Exercise | 217.5% | 15,000 | 21,896 | 23 Sep 2025 | Direct | ||
| Blair Tripodi | MASI | Restricted Stock Units | Options Exercise | -100% | -15,000 | 0 | 23 Sep 2025 | Direct | ||
| Politan Capital Management LP | MASI | Common Stock, par value $0.001 per share | Other | -2.69% | -126,888 | 4,589,648 | 29 Aug 2025 | See footnotes | ||
| Michelle Brennan | MASI | Common Stock | Purchase | 1.39% | $15,525 | $155.25 | 100 | 7,318 | 13 Aug 2025 | Direct |
| Michelle Brennan | MASI | Common Stock | Purchase | 1.4% | $15,035 | $150.35 | 100 | 7,218 | 12 Aug 2025 | Direct |
| William R. Jellison | MASI | Common Stock | Purchase | 167.6% | $437,940 | $145.98 | 3,000 | 4,790 | 11 Aug 2025 | Direct |
* marks a reported price that did not pass the local price check.