MASIMO CORP (MASI) Institutional Ownership Changes & 13F Activity
MASIMO CORP (MASI). Institutional ownership data tracks hedge funds, asset managers, and other institutional investors based on recent SEC Form 13F filings (Q1 2026). This page analyzes institutional buying and selling activity, new holdings, and sold-out positions in the latest reporting period. Notable filers include Fmr Llc, Pentwater Capital Management Lp, Barclays Plc, Hbk Investments L P, and Millennium Management Llc.
| Institution | Type | Change in shares | Change Position % | Shares | Reported stock balance | Portfolio quarter | Filing date |
|---|---|---|---|---|---|---|---|
| Neuberger Berman Group Llc | Buy | +398,303 | +7956.5% | 403,309 | $71.74M | Q1 2026 | Oct 27, 2026 |
| Op Asset Management Ltd | Sell | -8,207 | -100.0% | 0 | $0.00 | Q1 2026 | Sep 28, 2026 |
| M&T Bank Corp | Sell | -6,069 | -63.3% | 3,516 | $625.83K | Q1 2026 | Sep 04, 2026 |
| Ensign Peak Advisors, Inc | Sell | -2,711 | -100.0% | 0 | $0.00 | Q1 2026 | Aug 18, 2026 |
| O'Connor Alternative Investments Llc | Buy | +412,903 | — | 412,903 | $73.44M | Q1 2026 | Aug 14, 2026 |
| Taconic Capital Advisors Lp | Buy | +30,000 | — | 30,000 | $5.34M | Q1 2026 | Aug 14, 2026 |
| Oxford Asset Management Llp | Buy | +12,202 | — | 12,202 | $2.17M | Q1 2026 | Aug 14, 2026 |
| Brighton Jones Llc | Buy | +5,281 | — | 5,281 | $939.28K | Q1 2026 | Aug 07, 2026 |
| Verus Capital Partners, Llc | Sell | -3,651 | -100.0% | 0 | $0.00 | Q1 2026 | Jul 09, 2026 |
| Wells Fargo & Company/Mn | Sell | -7,360 | -39.4% | 11,337 | $2.02M | Q1 2026 | Jul 08, 2026 |
| Western Wealth Management, Llc | Buy | +250 | — | 250 | $44.47K | Q1 2026 | May 19, 2026 |
| Amundi | Buy | +199,283 | +454.4% | 243,143 | $43.25M | Q1 2026 | May 18, 2026 |
| Bank Of America Corp | Sell | -52,699 | -18.5% | 232,003 | $41.27M | Q1 2026 | May 18, 2026 |
| California State Teachers Retirement System | Buy | +9,464 | +21.6% | 53,287 | $9.48M | Q1 2026 | May 18, 2026 |
| South Dakota Investment Council | Sell | -3,700 | -17.4% | 17,568 | $3.13M | Q1 2026 | May 18, 2026 |
| Bull Harbor Capital Llc | Buy | +2,151 | — | 2,151 | $382.60K | Q1 2026 | May 18, 2026 |
| Fmr Llc | Sell | -6,413,341 | -81.6% | 1,450,823 | $258.06M | Q1 2026 | May 15, 2026 |
| Pentwater Capital Management Lp | Buy | +3,176,000 | — | 3,176,000 | $564.92M | Q1 2026 | May 15, 2026 |
| Barclays Plc | Buy | +2,685,627 | +4602.0% | 2,743,985 | $488.07M | Q1 2026 | May 15, 2026 |
| Hbk Investments L P | Buy | +2,576,109 | — | 2,576,109 | $458.21M | Q1 2026 | May 15, 2026 |
| Millennium Management Llc | Buy | +800,888 | +426.1% | 988,853 | $175.89M | Q1 2026 | May 15, 2026 |
| Balyasny Asset Management L.P. | Buy | +770,986 | — | 770,986 | $137.14M | Q1 2026 | May 15, 2026 |
| Fil Ltd | Buy | +482,000 | — | 482,000 | $85.73M | Q1 2026 | May 15, 2026 |
| Aqr Arbitrage Llc | Buy | +416,956 | — | 416,956 | $73.87M | Q1 2026 | May 15, 2026 |
| Alliancebernstein L.P. | Buy | +401,131 | +739.8% | 455,354 | $59.22M | Q1 2026 | May 15, 2026 |
| Goldman Sachs Group Inc | Buy | +347,494 | +54.6% | 984,192 | $175.06M | Q1 2026 | May 15, 2026 |
| Fort Baker Capital Management Lp | Buy | +312,720 | — | 312,720 | $55.62M | Q1 2026 | May 15, 2026 |
| Nexpoint Asset Management, L.P. | Buy | +310,130 | — | 310,130 | $55.16M | Q1 2026 | May 15, 2026 |
| Capitolis Liquid Global Markets Llc | Buy | +309,102 | — | 309,102 | $54.98M | Q1 2026 | May 15, 2026 |
| Aqr Capital Management Llc | Sell | -259,360 | -23.8% | 831,966 | $147.40M | Q1 2026 | May 15, 2026 |
Frequently asked questions about MASI activity
Which institutional owners are buying MASI?
Institutional owners buying MASI include investors who have either initiated new positions or increased their existing holdings based on recent SEC 13F filings. The activity table above highlights which funds added shares in the latest reporting periods and how their positions changed over time.
What does "buy" mean in MASI activity?
"Buy" means an investor increased their reported position in MASI compared to the prior reporting period. This reflects growing exposure to MASIMO CORP (MASI) rather than necessarily a brand-new position (though new positions also appear as buys when prior quantity was zero).
Is institutional interest in MASI increasing?
Institutional interest in MASI can be assessed by comparing the number of tracked funds adding or increasing positions versus those trimming or exiting across the periods shown. A higher number of additions typically signals increasing participation among large filers, but it should be read alongside position sizes and the full table.
Related MASI Institutional Insights
- MASI Overview
- MASI 13F Institutional Holders
- MASI Superinvestors
- Healthcare Sector Institutional Ownership
- Healthcare Sector Portfolio Overlap
- Institutional Portfolio Overlap & Shared Holdings
- Most Bought Healthcare Stocks By Institutional Investors
- Most Sold Healthcare Stocks By Institutional Investors
- MASI Insider Trading & SEC Form 4 Activity
- MASI Articles
- Top Institutional Investor Stock Rankings