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Of the 16 tracked institutions holding MASI, 9 have a 3-year clone track record — 7 of them beat the S&P. Average holder's clone alpha: +3.5pt. It's a gauge of who owns the name, not just how many.
Among the 16 tracked institutional investors we monitor, MASI (MASIMO CORP) is held with a combined value of $2.62B across 15,927,629 shares. The largest holder is BlackRock, Inc. with a position worth $826.13M (0.01% of their portfolio). 2 funds opened new positions in the most recent quarter. 6 funds increased their holdings. 8 funds reduced their position.
Total Institutional Value
$2.62B
Total Shares Held
15,927,629
Institutional Holders
16
Ranked by estimated dollars moved (share change × implied price). 13F data lags up to 45 days.
| # | Fund | Value↓ | Portfolio % | Change |
|---|---|---|---|---|
| 1 | BlackRock, Inc. | $826.13M | 0.01% | -47.6% |
| 2 | VANGUARD GROUP INC | $565.60M | 0.01% | -9.6% |
| 3 | FMR LLC | $258.06M | 0.01% | -81.6% |
| 4 | STATE STREET CORP | $255.73M | 0.01% | +1.6% |
| 5 | MILLENNIUM MANAGEMENT LLC | $227.22M | 0.09% | +579.6% |
| 6 | AQR CAPITAL MANAGEMENT LLC | $147.40M | 0.07% | -23.8% |
| 7 | Magnetar Financial LLC | $75.96M | 0.77% | +7729.2% |
| 8 | Capital Research Global Investors | $63.87M | 0.01% | -43.7% |
| 9 | Gotham Asset Management, LLC | $60.74M | 0.19% | -0.2% |
| 10 | CITADEL ADVISORS LLC | $50.05M | 0.04% | +553.5% |
SEC Schedule 13D (activist) and 13G (passive) filings for MASI. Filed when an investor acquires 5%+ ownership.
| Member | Type | Date |
|---|---|---|
| Kevin Hern | Sell | Sep 26, 2025 |
| Thomas R Tillis | Sell | Feb 13, 2015 |
As of the latest SEC 13F filings, BlackRock, Inc. is the largest institutional holder of MASI with a position worth $826.13M, representing 0.01% of their portfolio. In total, 16 institutional investors hold MASI with a combined value of $2.62B.
In the most recent quarter, 2 funds opened a new position in MASI. Additionally, 6 increased their holdings and 8 reduced their positions.
Institutional investors hold $2.62B worth of MASI stock across 16 positions. The largest institutional holder is BlackRock, Inc. with $826.13M in holdings.
A 13F filing is a quarterly report required by the SEC from institutional investment managers with over $100 million in assets. It discloses their holdings in U.S. equities. For MASI, these filings reveal which major funds are accumulating or reducing positions, providing insights into institutional sentiment.
Get notified when hedge funds change their MASI positions.
Alpha = the manager's 3-year clone return minus the S&P 500. A skilled roster is a stronger tell than a crowded one — though even skilled managers' edge doesn't reliably survive the 13F disclosure lag. Why →
