Masimo Corporation
MX ˙ BMV ˙ US5747951003
SecurityMX:MASI / Masimo Corporation
InstitutionWestmount Partners, LLC
Latest Disclosed Ownership24,232 shares
Latest Disclosed Value $ 4,310,146
Westmount Partners, LLC ownership in MASI / Masimo Corporation

On April 16, 2026 - Westmount Partners, LLC filed a 13F-HR form disclosing ownership of 24,232 shares of Masimo Corporation (MX:MASI) valued at $4,310,146 USD as of March 31, 2026. The entity filed a previous 13F-HR on January 15, 2026 disclosing 24,232 shares of Masimo Corporation. This represents a change in shares of 0.00% during the quarter.

Institutional Ownership: 13F and NPORT Filings

The Security and Class in the table below are shown exactly as filed by the investor. We do our best to track continuity of investments through acquisitions, and this will be reflected in the table as changes in names. In addition to descriptive data, performance of the investment is shown over time. To calculate quarterly performance, we first calculate cost basis of the shares purchased during the quarter, then use that to calculate gross profit. Quarterly return is Gross Profit / Starting Portfolio value.

Note that cost basis is calculated and stored in thousands, so small quarterly changes in shares frequently result in a cost basis of zero.

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Disclosed Equity Positions (from 13F/NPORT Filings)
File
Date		 Effective
Date		Form Security Class ID Avg Price
Paid (Est)		 Reported
Shares		 ΔShares ΔShares
(%)		 Reported
Value
(x1000)		 ΔValue
(%)		 Alloc
(%)		 ΔAlloc ΔAlloc (%) Cost Basis
(x1000)		 Unrealized
Gain/Loss
(x1000)
2026-04-16 2026-03-31 13F MASIMO COM 574795100 24,232 0 0.00 4,310 36.78 1.0609
2026-01-15 2025-12-31 13F MASIMO COM 574795100 24,232 -1,634 -6.32 3,152 -14.51 0.7857
2025-10-14 2025-09-30 13F MASIMO COM 574795100 25,866 0 0.00 3,687 -15.28 0.9521
2025-07-09 2025-06-30 13F MASIMO COM 574795100 25,866 -125 -0.48 4,351 0.48 1.1950
2025-05-01 2025-03-31 13F MASIMO COM 574795100 25,991 0 0.00 4,330 0.79 1.3207
2025-01-13 2024-12-31 13F MASIMO COM 574795100 25,991 0 0.00 4,296 23.98 1.3052
2025-01-13 2024-09-30 13F MASIMO COM 574795100 25,991 0 0.00 3,465 14.55 1.0421
2025-01-28 2024-06-30 13F MASIMO COM 574795100 25,991 -433 -1.64 3,025 -22.04 0.9986
2025-01-28 2024-03-31 13F MASIMO COM 574795100 26,424 0 0.00 3,880 25.28 1.3960
2025-01-28 2023-12-31 13F MASIMO COM 574795100 26,424 0 0.00 3,097 33.72 1.2647
2025-01-28 2023-09-30 13F MASIMO COM 574795100 26,424 0 0.00 2,317 -46.73 1.0206
2025-01-28 2023-06-30 13F MASIMO COM 574795100 26,424 0 0.00 4,348 -10.83 1.8926
2025-01-29 2023-03-31 13F MASIMO COM 574795100 26,424 -279 -1.04 4,876 23.44 2.2539
2025-01-28 2022-12-31 13F MASIMO COM 574795100 26,703 26,703 3,951 2.0525
Legend
Shares
The total number of shares held by the institution at the end of the reporting period (the effective date). This is provided in the filing.
Value
The total value of the shares as of the effective date. This is provided in the filing.
Avg. Share Price
The weighted average share price of the shares held by the institution. We use FIFO accounting to determine this price
Class
This is the security class as indicated by the filer. There are a variety of values for this field. Common values include "EC" = equity common, "EP" - equity preferred
Allocation (%)
The percent of the institution's portfolio that this position represents. This is provided in NPORT filings. For 13F filings, we calculate it.
Change in Allocation
The change in allocation from the prior reporting period. This is calculated as current allocation - prior allocation.
Change in Allocation (%)
The percent change in allocation from the prior reporting period. This is calculated as (current allocation - prior allocation) / prior allocation.
Cost Basis
The total cost of the shares held. This is calculated as reported shares * avg. share price
Unrealized Gain/Loss
This is the market value of the position as of the effective date minus the cost basis.