Ownership Submission
FORM 4
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
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, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
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(Print or Type Responses)
1. Name and Address of Reporting Person *
KIANI JOE E
   2. Issuer Name and Ticker or Trading Symbol
MASIMO CORP [MASI] 		5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
__X__ Director _____ 10% Owner
__X__ Officer (give title below) _____ Other (specify below)
CEO and Chairman of the Board
(Last)
(First)
(Middle)
C/O MASIMO CORPORATION, 52 DISCOVERY		 3. Date of Earliest Transaction (Month/Day/Year)
09/14/2018
(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 09/14/2018   M   72,928 A $ 27.25 202,169 D  
Common Stock 09/14/2018   S(1)   72,928 D $ 122.42 (2) 129,241 D  
Common Stock 09/14/2018   M   127,072 A $ 27.25 256,313 D  
Common Stock 09/14/2018   S(1)   127,072 D $ 123.1986 (3) 129,241 D  
Common Stock 09/14/2018   M   379 A $ 27.25 129,620 D  
Common Stock 09/14/2018   S(1)   379 D $ 124 129,241 D  
Common Stock 09/17/2018   M   176 A $ 27.25 129,417 D  
Common Stock 09/17/2018   S(1)   176 D $ 124 129,241 D  
Common Stock               229,290 I By Trust (4)
Common Stock               550,000 I By Trust (4)
Common Stock               352,919 I By Trust (4)
Common Stock               359,000 I By Trust (4)
Common Stock               2,250,291 I By Trust (5)
Common Stock               10,373 I See Footnote (6)
Common Stock               9,000 I See Footnote (7)

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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
Non-Qualified Stock Option (Right to Buy) $ 27.25 09/14/2018   M     72,928 02/11/2011(8) 02/11/2020 Common Stock 72,928 $ 27.25 227,072 D  
Non-Qualified Stock Option (Right to Buy) $ 27.25 09/14/2018   M     127,072 02/11/2011(8) 02/11/2020 Common Stock 127,072 $ 27.25 100,000 D  
Non-Qualified Stock Option (Right to Buy) $ 27.25 09/14/2018   M     379 02/11/2011(8) 02/11/2020 Common Stock 379 $ 27.25 99,621 D  
Non-Qualified Stock Option (Right to Buy) $ 27.25 09/17/2018   M     176 02/11/2011(8) 02/11/2020 Common Stock 176 $ 27.25 99,445 D  

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
KIANI JOE E
C/O MASIMO CORPORATION
52 DISCOVERY
IRVINE, CA 92618		   X     CEO and Chairman of the Board  

Signatures

 /s/ Micah Young, Attorney-In-Fact   09/18/2018
**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) The shares covered by this Form 4 were exercised and sold pursuant to a Rule 10b5-1 Sales Plan dated as of August 23, 2018, which is intended to comply with Rule 10b5-1 promulgated under the Securities Exchange Act of 1934, as amended.
(2) The price reported in Column 4 represents the weighted average sale price per share. The actual sale prices ranged from a low of $122.00 per share to a high of $122.99 per share. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer, or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.
(3) The price reported in Column 4 represents the weighted average sale price per share. The actual sale prices ranged from a low of $123.00 per share to a high of $123.60 per share. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer, or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.
(4) Shares held in four trusts for which Mr. Kiani is not the trustee.
(5) Shares held in one trust for which Mr. Kiani is the sole trustee.
(6) Shares held in Masimo Retirement Savings Plan.
(7) Shares held by an immediate family member for which Mr. Kiani exercises voting and investment control.
(8) This option was granted on February 11, 2010 and is exercisable as the option vests. This option vested over a five year period, with 20% of the shares subject to the option vesting on each anniversary of the grant date.

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