MASIMO CORP (MASI) Stock Institutional Trading Activity
MASIMO CORP (MASI) position changes reported by tracked institutional filers across multiple SEC 13F reporting periods. Based on recent SEC 13F filings (Q4 2025), investors with some of the largest reported share count changes include Viking Global Investors, Renaissance Technologies LLC, Durable Capital Partners, Fundsmith, and Polen Capital Management. Explore insights into buying and selling patterns, position changes, and investment conviction levels to understand institutional trading behavior and market dynamics.
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- MASIMO CORP (MASI) stock institutional ownership
- MASIMO CORP (MASI) stock insider trading activity
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| Portfolio quarter | Name | Type | Quantity | Remaining | Reported stock balance |
|---|---|---|---|---|---|
| Q4 2015 | Renaissance Technologies LLC | Buy | 109,200 | 222,400 | $9,232 |
| Q3 2015 | Renaissance Technologies LLC | Sell | -42,400 | 113,200 | $4,365 |
| Q2 2015 | Renaissance Technologies LLC | Buy | 12,900 | 155,600 | $6,028 |
| Q1 2015 | Renaissance Technologies LLC | Buy | 42,600 | 142,700 | $4,706 |
| Q4 2014 | Renaissance Technologies LLC | Sell | -236,100 | 100,100 | $2,637 |
| Q3 2014 | Renaissance Technologies LLC | Buy | 73,965 | 336,200 | $7,154 |
| Q2 2014 | Renaissance Technologies LLC | Buy | 201,635 | 262,235 | $6,189 |
| Q4 2013 | Bares Capital Management | Sell | -237,262 | 2,153,144 | $62,936 |
| Q3 2013 | Renaissance Technologies LLC | Sell | -396,600 | 60,600 | $1,614 |
| Q3 2013 | Bares Capital Management | Sell | -647,065 | 2,390,406 | $63,676 |
| Q2 2013 | Renaissance Technologies LLC | Buy | 457,200 | 457,200 | $9,693 |
| Q2 2013 | Bares Capital Management | Buy | 3,037,471 | 3,037,471 | $64,394 |
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.