Masimo Corporation (MASI) Shareholders & Insider Trades
Masimo shareholders at a glance
The largest holder of Masimo stock is Politan Capital Management LP, with 4.6 million shares (8.77% of the company), worth about $819.00 million as of May 18, 2026. The 10 largest holders together own 59.0%.
In Q2 2026, 2 institutional holdings reports listed 90 shares worth $16,200.
Insiders reported 37 transactions in the last two years: 4 sales worth $9.55 million and 2 purchases. The newest one on file is from April 29, 2026 (Lane Wendy E., Director).
Major holders as of May 18, 2026; quarterly totals from institutional holdings reports (latest Q2 2026); insider transactions on file through April 29, 2026.
Masimo Corporation
Shareholders Summary
2026Q2
Ownership by Type
Geographic Distribution
Largest Masimo shareholders
| Holder | Shares | % of company | Value |
|---|---|---|---|
| Politan Capital Management LP | 4.6 million | 8.77% | $819.0M |
| Politan Capital Management LP | 4.6 million | 8.76% | $818.0M |
| BlackRock Advisors LLC | 4.4 million | 8.49% | $794.0M |
| Pentwater Capital Management LP | 3.2 million | 6.07% | $567.0M |
| Barclays Bank Plc | 2.7 million | 5.24% | $490.0M |
| HBK Investments LP | 2.6 million | 4.92% | $460.0M |
| Fidelity Management & Research Co. LLC | 2.3 million | 4.49% | $419.0M |
| MFS Investment Management Canada Ltd. | 2.3 million | 4.47% | $418.0M |
| Vanguard Capital Management LLC | 2.1 million | 3.92% | $366.0M |
| Vanguard Portfolio Management LLC | 2.0 million | 3.83% | $358.0M |
As of May 18, 2026.
Masimo institutional holdings by quarter
| Quarter | Reports | Shares | Value |
|---|---|---|---|
| Q2 2026 | 2 | 90 | $16,200 |
| Q1 2026 | 476 | 54.6 million | $9.7B |
| Q4 2025 | 404 | – | $7.3B |
| Q3 2025 | 370 | – | $8.3B |
| Q2 2025 | 391 | 57.6 million | $9.7B |
| Q1 2025 | 407 | 54.3 million | $9.0B |
| Q4 2024 | 384 | 51.4 million | $8.5B |
| Q3 2024 | 389 | 50.7 million | $6.8B |
Shares and value held by institutions that file quarterly holdings reports (options not included).
Masimo insider trades
| Insider | Date | Title | Transaction | Value |
|---|---|---|---|---|
| Lane Wendy E. | Apr 29, 2026 | Director | -- | – |
| Scannell Timothy J. | Apr 29, 2026 | Director | -- | – |
| Brennan Michelle | Apr 29, 2026 | Chairman of the Board | -- | – |
| Hellmann Elisabeth A | Apr 21, 2026 | Officer | -- | – |
| Szyman Catherine M | Mar 11, 2026 | Chief Executive Officer | -- | – |
| Young Micah W | Mar 11, 2026 | Chief Financial Officer | -- | – |
| Young Micah W | Feb 27, 2026 | Chief Financial Officer | Conversion of Exercise of derivative security at price 175.35 per share. | $2.6M |
| Young Micah W | Feb 27, 2026 | Chief Financial Officer | Stock Award(Grant) at price 0.00 per share. | – |
| Young Micah W | Feb 26, 2026 | Chief Financial Officer | Stock Award(Grant) at price 0.00 per share. | – |
| Szyman Catherine M | Feb 12, 2026 | Chief Executive Officer | Conversion of Exercise of derivative security at price 132.96 per share. | $1.5M |
| Sampath Anand | Jan 28, 2026 | Officer | Conversion of Exercise of derivative security at price 37.84 per share. | $1.1M |
| Sampath Anand | Jan 28, 2026 | Officer | Sale at price 136.56 - 138.09 per share. | $2.6M |
Newest 12 of 37 insider transactions in the last two years.
Questions and answers
Who owns the most Masimo stock?
Politan Capital Management LP, with 8.77% of the company (as of May 18, 2026). Next: Politan Capital Management LP (8.76%) and BlackRock Advisors LLC (8.49%).
How many institutions own Masimo stock?
2 institutional holdings reports listed Masimo shares in Q2 2026, 90 shares in all worth $16,200.
Are Masimo insiders buying or selling the stock?
In the last two years insiders reported 4 sales and 2 purchases (37 transactions in all); the newest on file is from April 29, 2026.
