MASI Institutional Ownership & Shareholders
MASIMO CORP (MASI) is currently held by 13 institutional investors tracked by InsiderSet, with a combined reported market value of approximately $135.13M based on the latest available SEC Form 13F filings for the quarter ended March 31, 2026.
O'Connor Alternative Investments Llc is currently the largest disclosed institutional shareholder of MASI tracked by InsiderSet, reporting ownership valued at approximately $73.44M 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 $74.30M, representing an estimated gain of +1.17% since the filing period.
The top 10 institutional shareholders tracked on this page collectively account for approximately 100% of the total disclosed MASI value among the investors covered in this analysis. Major shareholders include O'Connor Alternative Investments Llc, Ubs Am, A Distinct Business Unit Of Ubs Asset Management Americas Llc, Cibra Capital Ltd, 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
13
Total Reported Value
$135.13M
Largest Holder
O'Connor Alternative Investments Llc
Largest Position
$73.44M
Insider Transactions (90d)
0
Latest Filing Quarter
Q1 2026
New Institutional Positions
108
Funds Exiting Positions
0
| Name | Investor/Manager | Portfolio % | Quantity | Reported Balance | Current Estimated Value | Gain/loss Since Filing | Estimated Portfolio Performance |
|---|---|---|---|---|---|---|---|
| O'Connor Alternative Investments Llc | 9.91% | 412,903 | $73,443,057 | $74,301,895 | +$858,838 | +1.17% | |
| Ubs Am, A Distinct Business Unit Of Ubs Asset Management Americas Llc | 0.00% | 133,689 | $23,779,262 | $24,057,336 | +$278,074 | +1.17% | |
| Cibra Capital Ltd | 7.76% | 90,376 | $16,075,179 | $16,263,161 | +$187,982 | +1.17% | |
| Cwm, Llc | 0.02% | 34,690 | $6,170,310 | $6,242,466 | +$72,156 | +1.17% | |
| Taconic Capital Advisors Lp | 86.47% | 30,000 | $5,336,100 | $5,398,500 | +$62,400 | +1.17% | |
| Advisors Asset Management, Inc. | 0.05% | 13,028 | $3,814,338 | $2,344,389 | -$1,469,949 | -38.54% | |
| Janus Henderson Group Plc | 0.00% | 20,000 | $3,557,000 | $3,599,000 | +$42,000 | +1.18% | |
| Pathstone Holdings, Llc | 0.01% | 7,386 | $1,313,747 | $1,329,111 | +$15,364 | +1.17% | |
| Neuberger Berman Group Llc | 0.00% | 5,006 | $651,080 | $900,830 | +$249,750 | +38.36% | |
| M&T Bank Corp | 0.00% | 3,516 | $625,830 | $632,704 | +$6,874 | +1.10% | |
| Brooklyn Investment Group | 0.01% | 2,015 | $358,409 | $362,599 | +$4,190 | +1.17% | |
| Huntington National Bank | 0.00% | 2 | $360 | $360 | -$0 | -0.03% | |
| Bare Financial Services, Inc | 0.00% | 2 | $356 | $360 | +$4 | +1.10% |
Frequently asked questions about MASI
Who are the largest institutional holders of MASI?
The largest institutional holders of MASI reported in the latest SEC Form 13F filings include O'Connor Alternative Investments Llc, Ubs Am, A Distinct Business Unit Of Ubs Asset Management Americas Llc, Cibra Capital Ltd, Cwm, Llc, and Taconic Capital Advisors Lp. InsiderSet ranks institutional holders by their latest reported MASI position.
What is MASI institutional ownership?
This page tracks MASI positions reported by institutional investment managers through SEC Form 13F. MASIMO CORP (MASI) institutional ownership on InsiderSet reflects disclosed 13F holdings among the managers we analyze, not every shareholder of the stock.
How many institutions own MASI?
InsiderSet currently tracks 13 institutional managers reporting MASI holdings in the latest available 13F data. This count reflects institutions included in the SEC Form 13F filings analyzed by InsiderSet and should not be interpreted as the total number of MASI shareholders.
How much MASI stock do institutions own?
Institutional investment managers disclosed approximately $135.13M in MASI holdings for Q1 2026. This figure is reported 13F value as of the filing period, not necessarily today's market value.
When was MASI institutional ownership last updated?
The latest MASI institutional ownership data on InsiderSet is based on SEC Form 13F filings for the quarter ended March 31, 2026. Form 13F filings are generally reported after the quarter ends, so the holdings shown represent the latest publicly disclosed positions rather than real-time institutional holdings.
Are institutional MASI holdings real-time?
No. Form 13F data is not real-time. It represents positions reported by institutional investment managers as of the end of the reporting quarter. An institution may have changed its MASI position after the reporting date.
Are institutions buying or selling MASI?
Institutional buying and selling can be analyzed by comparing MASI positions across consecutive 13F reporting periods. InsiderSet's MASI Ownership Changes page shows institutions that increased, reduced, initiated, or exited positions based on reported 13F holdings. View MASI ownership changes.
How has MASI institutional ownership changed over time?
InsiderSet tracks MASI institutional holdings across multiple 13F reporting periods, allowing investors to compare institutional holder counts, reported value, and reported shares over time.