RTW Investments MASI Position
Active3-Fund ConvergenceRTW Investments held their position in Masimo Corporation (MASI) in Q4 2025, holding $88.9M worth of shares across 683,294 shares.
The position was first reported in Q1 2023 and has been tracked across 12 quarterly 13F filings.
MASI is a convergence signal: 3 specialist biotech funds hold this stock, suggesting high institutional conviction.
About Masimo Corporation
Masimo Corporation develops, manufactures, and markets noninvasive monitoring technologies and hospital automation solutions worldwide. The company offers masimo signal extraction technology (SET) pulse oximetry with measure-through motion and low perfusion pulse oximetry monitoring to address the primary limitations of conventional pulse oximetry. It also provides Masimo rainbow SET platform that includes rainbow SET Pulse CO-Oximetry products that noninvasively monitor hemoglobin species, including oxygen saturation, pulse rate, perfusion index, pleth variability index, and respiration rate from the pleth; noninvasively monitor hemoglobin concentration, and carboxyhemoglobin and methemoglobin; monitor arterial oxygen saturation and acoustic respiration rate; and calculates oxygen content and oxygen reserve index. It offers SedLine brain function monitoring technology to measure the brain's electrical activity by detecting EEG signals; capnography and gas monitoring products comprising external plug-in-and-measure capnography and gas analyzers, integrated modules, handheld capnograph and capnometer devices, and capnography sampling lines; O3 regional oximetry for tissue oxygen saturation measurement; and hemodynamic monitoring solutions. Its Masimo Hospital Automation platform includes Patient SafetyNet, Patient SafetyNet surveillance, Kite, UniView, Replica, UniView : 60, and MyView. It offers connectivity devices; and nasal high flow ventilation and neuromodulation solutions. It provides its products through direct sales force, distributors, and original equipment manufacturers partners to hospitals, emergency medical service and home care providers, long-term care facilities, physician offices, veterinarians, and consumers; and non-medical/consumer products through e-commerce site, masimopersonalhealth.com. The company was incorporated in 1989 and is headquartered in Irvine, California.
Full company profile →Short Interest
7.6%
0.9 days to cover
RTW Investments MASI Position History
| Quarter | Action | Shares | Change | Value |
|---|---|---|---|---|
| Q4 2025 | Held | 683,294 | — | $88.9M |
| Q3 2025 | Held | 683,294 | — | $100.8M |
| Q2 2025 | Held | 683,294 | — | $114.9M |
| Q1 2025 | Held | 683,294 | — | $113.8M |
| Q4 2024 | Decreased | 683,294 | -779,106 | $112.9M |
| Q3 2024 | Held | 1,462,400 | — | $195.0M |
| Q2 2024 | Held | 1,462,400 | — | $184.2M |
| Q1 2024 | Held | 1,462,400 | — | $214.8M |
| Q4 2023 | Decreased | 1,462,400 | -39,093 | $171.4M |
| Q3 2023 | Held | 1,501,493 | — | $131.7M |
| Q2 2023 | Held | 1,501,493 | — | $247.1M |
| Q1 2023 | New | 1,501,493 | +1,501,493 | $277.1M |
Frequently Asked Questions
Does RTW Investments own MASI?
Yes. As of Q4 2025, RTW Investments holds 683,294 shares of Masimo Corporation (MASI) valued at $88.9M. This data comes from their SEC 13F filing.
How many hedge funds own MASI?
3 specialist biotech hedge funds currently hold MASI, including Redmile Group, Deerfield Management. When 3 or more specialist funds hold the same stock, BiotechEdge flags it as a convergence signal.
When did RTW Investments first buy MASI?
RTW Investments's position in MASI was first reported in Q1 2023. 13F filings are reported with a 45-day delay, so the actual purchase may have occurred earlier in the quarter.
Is RTW Investments's MASI position increasing or decreasing?
RTW Investments held their MASI position unchanged in the most recent quarter.
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