Masimo
MASI
MASI was delisted on the 9th of June, 2026.
393 hedge funds and large institutions have $7.2B invested in Masimo in 2025 Q4 according to their latest regulatory filings, with 86 funds opening new positions, 102 increasing their positions, 132 reducing their positions, and 50 closing their positions.
72% more first-time investments, than exits
New positions opened: 86 | Existing positions closed: 50
9% more funds holding
Funds holding: 360 → 393 (+33)
0% more funds holding in top 10
Funds holding in top 10: 4 → 4 (0)
0.66% less ownership
Funds ownership: 103.71% → 103.04% (-0.66%)
13% less capital inflows, than outflows
Capital inflows: $955M | Capital outflows: $1.1B
23% less repeat investments, than reductions
Existing positions increased: 102 | Existing positions reduced: 132
63% less call options, than puts
Call options by funds: $3.55M | Put options by funds: $9.7M
Top Buyers
| Rank | Fund | Capital Flow |
|---|---|---|
| 1 |
NAYA Capital Management (UK)
London,
United Kingdom
|
+$223M |
| 2 |
AQR Capital Management
Greenwich,
Connecticut
|
+$152M |
| 3 |
UBS Group
Zurich,
Switzerland
|
+$61.5M |
| 4 |
Qube Research & Technologies (QRT)
London,
United Kingdom
|
+$42M |
| 5 |
Schonfeld Strategic Advisors
New York
|
+$36.4M |
Top Sellers
| Rank | Fund | Capital Flow |
|---|---|---|
| 1 |
BlackRock
New York
|
-$216M |
| 2 |
Capital Research Global Investors
Los Angeles,
California
|
-$174M |
| 3 |
Durable Capital Partners
Bethesda,
Maryland
|
-$91.6M |
| 4 |
Viking Global Investors
Stamford,
Connecticut
|
-$80.1M |
| 5 |
Vanguard Group
Malvern,
Pennsylvania
|
-$66M |
MASI Hedge Fund Activity: Q4 2025 in Review
393 of the 8,307 institutional investors tracked by Wall St. Rank reported a position in Masimo (MASI) for Q4 2025, worth a combined $7.2B — down 13% from $8.31B a quarter earlier.
Buyers outnumbered sellers: 86 funds opened new MASI positions and 50 closed out — a net gain of 36 holders — while 102 added to existing stakes and 132 trimmed.
The largest buyer was NAYA Capital Management (UK), opening a new position worth an estimated $223M. The largest seller was BlackRock, cutting an estimated $216M.
- 393 institutional investors held Masimo (MASI) as of Q4 2025, up from 360 in Q3 2025.
- Funds reported $7.2B of Masimo stock for Q4 2025, down 13% quarter-over-quarter.
- 86 funds opened new Masimo positions in Q4 2025 and 50 closed out, a net change of +36 holders.
- The largest Masimo buyer in Q4 2025 was NAYA Capital Management (UK), an estimated $223M added.
- The largest Masimo seller in Q4 2025 was BlackRock, an estimated $216M sold.
Based on aggregated 13F filings for Q4 2025.