MASIMO CORP (MASI) Top Institutional Shareholders
MASIMO CORP (MASI) is currently reported in institutional portfolios tracked by InsiderSet based on the latest available SEC Form 13F filings for the quarter ended March 31, 2026. The institutional investors covered on this page collectively reported approximately $9.23B in MASI holdings during the latest filing period.
Blackrock, Inc. is currently the largest disclosed institutional shareholder of MASI tracked by InsiderSet, reporting ownership valued at approximately $826.13M in its March 31, 2026 SEC Form 13F filing. Based on current market prices and the latest disclosed share count, the position is now estimated to be worth approximately $835.79M, representing an estimated gain of +1.17% since the filing period.
The top 10 institutional shareholders tracked on this page collectively account for approximately 52% of the total disclosed MASI value among the investors covered in this analysis. Major shareholders include Blackrock, Inc., Politan Capital Management Lp, Pentwater Capital Management Lp, and several other long-term asset managers with concentrated positions in MASIMO CORP (MASI).
This page ranks the largest institutional MASI shareholders using publicly disclosed SEC Form 13F data, including reported values, estimated current holding values, portfolio allocation percentages, ownership concentration metrics, and historical holding changes across major hedge funds and investment firms.
Institutional Holders
437
Total Reported Value
$9.23B
Largest Holder
Blackrock, Inc.
Largest Position
$826.13M
Insider Transactions (90d)
0
Latest Filing Quarter
Q1 2026
New Institutional Positions
107
Funds Exiting Positions
0
| Name | Investor/Manager | Portfolio % | Quantity | Reported Balance | Current Estimated Value | Gain/loss Since Filing | Estimated Portfolio Performance |
|---|---|---|---|---|---|---|---|
| Blackrock, Inc. | 0.01% | 4,644,578 | $826,131,120 | $835,791,811 | +$9,660,691 | +1.17% | |
| Politan Capital Management Lp | 82.89% | 4,589,648 | $816,360,690 | $825,907,158 | +$9,546,468 | +1.17% | |
| Pentwater Capital Management Lp | 4.01% | 3,176,000 | $564,915,120 | $571,521,200 | +$6,606,080 | +1.17% | |
| Barclays Plc | 0.17% | 2,743,985 | $488,072,611 | $493,780,101 | +$5,707,490 | +1.17% | |
| Hbk Investments L P | 5.77% | 2,576,109 | $458,212,508 | $463,570,815 | +$5,358,307 | +1.17% | |
| Massachusetts Financial Services Co | 0.14% | 2,342,790 | $416,692,672 | $421,585,061 | +$4,892,389 | +1.17% | |
| Vanguard Capital Management Llc | 0.01% | 2,050,045 | $364,641,504 | $368,905,598 | +$4,264,094 | +1.17% | |
| Vanguard Portfolio Management Llc | 0.02% | 2,006,861 | $356,960,366 | $361,134,637 | +$4,174,271 | +1.17% | |
| Fmr Llc | 0.01% | 1,450,823 | $258,057,947 | $261,075,599 | +$3,017,652 | +1.17% | |
| State Street Corp | 0.01% | 1,437,724 | $255,727,968 | $258,718,434 | +$2,990,466 | +1.17% | |
| Millennium Management Llc | 0.13% | 988,853 | $175,887,283 | $177,944,097 | +$2,056,814 | +1.17% | |
| Goldman Sachs Group Inc | 0.02% | 984,192 | $175,058,231 | $177,105,350 | +$2,047,119 | +1.17% | |
| Geode Capital Management, Llc | 0.01% | 956,736 | $170,210,661 | $172,164,643 | +$1,953,982 | +1.15% | |
| Aqr Capital Management Llc | 0.07% | 831,966 | $147,399,452 | $149,712,282 | +$2,312,830 | +1.57% | |
| Balyasny Asset Management L.P. | 0.27% | 770,986 | $137,135,280 | $138,738,931 | +$1,603,651 | +1.17% | |
| Morgan Stanley | 0.01% | 752,417 | $133,832,703 | $135,397,439 | +$1,564,736 | +1.17% | |
| Citigroup Inc | 0.06% | 533,388 | $94,873,724 | $95,983,171 | +$1,109,447 | +1.17% | |
| Fil Ltd | 0.07% | 482,000 | $85,733,340 | $86,735,900 | +$1,002,560 | +1.17% | |
| First Trust Capital Management L.P. | 4.48% | 479,403 | $85,271,412 | $86,268,570 | +$997,158 | +1.17% | |
| Hsbc Holdings Plc | 0.05% | 473,434 | $84,266,518 | $85,194,448 | +$927,930 | +1.10% | |
| Ubs Group Ag | 0.01% | 468,257 | $83,288,873 | $84,262,847 | +$973,974 | +1.17% | |
| Liontrust Investment Partners Llp | 1.21% | 627,796 | $81,651,148 | $112,971,890 | +$31,320,742 | +38.36% | |
| Magnetar Financial Llc | 0.77% | 427,081 | $75,964,897 | $76,853,226 | +$888,329 | +1.17% | |
| Aqr Arbitrage Llc | 1.21% | 416,956 | $73,872,095 | $75,031,232 | +$1,159,137 | +1.57% | |
| Neuberger Berman Group Llc | 0.05% | 403,309 | $71,736,572 | $72,575,455 | +$838,883 | +1.17% | |
| Northern Trust Corp | 0.01% | 390,437 | $69,447,030 | $70,259,138 | +$812,108 | +1.17% | |
| Squarepoint Ops Llc | 0.15% | 389,359 | $69,255,285 | $70,065,152 | +$809,867 | +1.17% | |
| Charles Schwab Investment Management Inc | 0.01% | 386,898 | $68,817,547 | $69,622,295 | +$804,748 | +1.17% | |
| Capital Research Global Investors | 0.01% | 359,058 | $63,865,646 | $64,612,487 | +$746,841 | +1.17% | |
| Gotham Asset Management, Llc | 0.19% | 341,468 | $60,736,913 | $61,447,167 | +$710,254 | +1.17% | |
| Westfield Capital Management Co Lp | 0.25% | 341,229 | $60,694,349 | $61,404,159 | +$709,810 | +1.17% | |
| Alliancebernstein L.P. | 0.02% | 455,354 | $59,223,341 | $81,940,952 | +$22,717,611 | +38.36% | |
| Hudson Bay Capital Management Lp | 0.37% | 330,679 | $58,817,874 | $59,505,686 | +$687,812 | +1.17% | |
| Corient Private Wealth Llc | 0.08% | 321,600 | $57,202,996 | $57,871,920 | +$668,924 | +1.17% | |
| Fort Baker Capital Management Lp | 4.93% | 312,720 | $55,623,507 | $56,273,964 | +$650,457 | +1.17% | |
| Nexpoint Asset Management, L.P. | 3.85% | 310,130 | $55,162,823 | $55,807,894 | +$645,071 | +1.17% | |
| Capitolis Liquid Global Markets Llc | 0.35% | 309,102 | $54,979,973 | $55,622,905 | +$642,932 | +1.17% | |
| Bank Of New York Mellon Corp | 0.01% | 306,400 | $54,499,447 | $55,136,680 | +$637,233 | +1.17% | |
| Qube Research & Technologies Ltd | 0.07% | 291,481 | $51,845,725 | $52,452,006 | +$606,281 | +1.17% | |
| Vanguard Fiduciary Trust Co | 0.01% | 289,867 | $51,558,643 | $52,161,567 | +$602,924 | +1.17% | |
| Citadel Advisors Llc | 0.04% | 281,366 | $50,046,570 | $50,631,812 | +$585,242 | +1.17% | |
| Whitebox Advisors Llc | 0.69% | 270,001 | $48,025,078 | $48,586,680 | +$561,602 | +1.17% | |
| Nuance Investments, Llc | 6.07% | 244,704 | $43,525,500 | $44,034,485 | +$508,985 | +1.17% | |
| Amundi | 0.01% | 243,143 | $43,247,846 | $43,753,583 | +$505,737 | +1.17% | |
| Slotnik Capital, Llc | 12.70% | 240,300 | $42,742,161 | $43,241,985 | +$499,824 | +1.17% | |
| Renaissance Technologies LLC | Jim Simons | 0.07% | 239,500 | $42,599,865 | $43,098,025 | +$498,160 | +1.17% |
| Polar Asset Management Partners Inc. | 0.98% | 232,026 | $41,270,465 | $41,753,079 | +$482,614 | +1.17% | |
| Bank Of America Corp | 0.00% | 232,003 | $41,266,373 | $41,748,940 | +$482,567 | +1.17% | |
| Mufg Securities Emea Plc | 0.60% | 225,400 | $40,091,898 | $40,560,730 | +$468,832 | +1.17% | |
| Beryl Capital Management Llc | 35.54% | 217,103 | $38,616,111 | $39,067,685 | +$451,574 | +1.17% |
Frequently asked questions about MASI
Who owns the most MASI stock?
The largest holders of MASI are typically major institutional investors such as asset managers and hedge funds reporting on Form 13F. The table above ranks tracked superinvestors by reported position size using the latest available filings for MASIMO CORP (MASI).
Is MASI widely held by superinvestors?
Many widely followed stocks like MASI appear across numerous superinvestor portfolios because of liquidity, index inclusion, and fundamentals. The holder count and table above show how broadly MASI is represented among the institutional managers we track.
What do “Current Estimated Value”, “Gain/loss Since Filing”, and “Estimated Portfolio Performance” mean?
Current Estimated Value is reported share quantity from the latest 13F times our most recent split-adjusted U.S. session close. Gain/loss Since Filing is that estimate minus the reported 13F dollar value; Estimated Portfolio Performance is that difference as a percent of the reported value. Green means the estimate is above the filing value; red means below (not purchase cost). If many filers share the same implied filing price per share, the performance % may match across rows. These are not official fund marks or live quotes.