Statement of Changes in Beneficial Ownership (Form 4)

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b). Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person * Young Micah W 2. Issuer Name and Ticker or Trading Symbol MASIMO CORP [MASI] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) EVP & Chief Financial Officer (Last) (First) (Middle) C/O MASIMO CORPORATION, 52 DISCOVERY 3. Date of Earliest Transaction (Month/Day/Year) 02/27/2026 (Street) IRVINE, CA 92618 4. If Amendment, Date Original Filed (Month/Day/Year) 6. Individual or Joint/Group Filing (Check Applicable Line) _X_ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 02/27/2026 A 15,000(1)(2) A $ 0 33,347 D Common Stock 02/27/2026 F 8,093(3) D $175.35 25,254 D

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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Restricted Stock Units

(4)

02/27/2026

M

15,000

(1)

(1)

Common Stock

15,000

$ 0

0

D

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Young Micah W C/O MASIMO CORPORATION 52 DISCOVERY IRVINE, CA 92618			EVP & Chief Financial Officer

Signatures

/s/ Micah W. Young, Attorney-In-Fact		03/03/2026
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	As previously reported, the reporting person was granted 30,000 restricted stock units on March 1, 2024, 50% of which vested on March 1, 2025. The remaining 15,000 restricted stock units vested on February 27, 2026.
(2)	For the vesting that occurred on March 1, 2026, the Issuer calculated the number of vested shares and shares withheld for tax liability based on its closing stock price on the immediately preceding business day. As a result, the Reporting person received 6,907 shares of common stock, as shown in Table I.
(3)	These shares were withheld by the Issuer in order to satisfy certain tax withholding obligations in connection with the issuance of shares upon the vesting of certain restricted stock units.
(4)	Each restricted stock unit (RSU) represents the contingent right to receive one share of common stock of the Issuer upon vesting of the RSU.

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