<SEC-DOCUMENT>0001104659-25-043642.txt : 20250501
<SEC-HEADER>0001104659-25-043642.hdr.sgml : 20250501
<ACCEPTANCE-DATETIME>20250501203340
ACCESSION NUMBER:		0001104659-25-043642
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20250429
FILED AS OF DATE:		20250501
DATE AS OF CHANGE:		20250501

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Koffey Quentin
		CENTRAL INDEX KEY:			0001984174
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-33642
		FILM NUMBER:		25905153

	MAIL ADDRESS:	
		STREET 1:		POLITAN CAPITAL MANAGEMENT LP
		STREET 2:		106 WEST 56TH STREET, 10TH FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10019

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Politan Capital Management LP
		CENTRAL INDEX KEY:			0001885245
		ORGANIZATION NAME:           	
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-33642
		FILM NUMBER:		25905156

	BUSINESS ADDRESS:	
		STREET 1:		106 WEST 56TH STREET
		STREET 2:		10TH FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10019
		BUSINESS PHONE:		(212) 756-2000

	MAIL ADDRESS:	
		STREET 1:		106 WEST 56TH STREET
		STREET 2:		10TH FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10019

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Politan Capital Management GP LLC
		CENTRAL INDEX KEY:			0001984176
		ORGANIZATION NAME:           	
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-33642
		FILM NUMBER:		25905155

	BUSINESS ADDRESS:	
		STREET 1:		106 WEST 56TH STREET, 10TH FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10019
		BUSINESS PHONE:		646-690-2830

	MAIL ADDRESS:	
		STREET 1:		106 WEST 56TH STREET, 10TH FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10019

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Politan Capital Partners GP LLC
		CENTRAL INDEX KEY:			0001984175
		ORGANIZATION NAME:           	
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-33642
		FILM NUMBER:		25905154

	BUSINESS ADDRESS:	
		STREET 1:		106 WEST 56TH STREET, 10TH FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10019
		BUSINESS PHONE:		646-690-2830

	MAIL ADDRESS:	
		STREET 1:		106 WEST 56TH STREET, 10TH FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10019

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MASIMO CORP
		CENTRAL INDEX KEY:			0000937556
		STANDARD INDUSTRIAL CLASSIFICATION:	ELECTROMEDICAL & ELECTROTHERAPEUTIC APPARATUS [3845]
		ORGANIZATION NAME:           	08 Industrial Applications and Services
		EIN:				330368882
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1228

	BUSINESS ADDRESS:	
		STREET 1:		52 DISCOVERY
		CITY:			IRVINE
		STATE:			CA
		ZIP:			92618
		BUSINESS PHONE:		949-297-7000

	MAIL ADDRESS:	
		STREET 1:		52 DISCOVERY
		CITY:			IRVINE
		STATE:			CA
		ZIP:			92618
</SEC-HEADER>
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<TYPE>4
<SEQUENCE>1
<FILENAME>tm2513809-1_4seq1.xml
<DESCRIPTION>OWNERSHIP DOCUMENT
<TEXT>
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    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2025-04-29</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000937556</issuerCik>
        <issuerName>MASIMO CORP</issuerName>
        <issuerTradingSymbol>MASI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001885245</rptOwnerCik>
            <rptOwnerName>Politan Capital Management LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>106 WEST 56TH STREET</rptOwnerStreet1>
            <rptOwnerStreet2>10TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10019</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
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            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <officerTitle></officerTitle>
            <otherText>Director by deputization</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001984176</rptOwnerCik>
            <rptOwnerName>Politan Capital Management GP LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>106 WEST 56TH STREET</rptOwnerStreet1>
            <rptOwnerStreet2>10TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10019</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <officerTitle></officerTitle>
            <otherText>Director by deputization</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001984175</rptOwnerCik>
            <rptOwnerName>Politan Capital Partners GP LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>106 WEST 56TH STREET</rptOwnerStreet1>
            <rptOwnerStreet2>10TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10019</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <officerTitle></officerTitle>
            <otherText>Director by deputization</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001984174</rptOwnerCik>
            <rptOwnerName>Koffey Quentin</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>106 WEST 56TH STREET</rptOwnerStreet1>
            <rptOwnerStreet2>10TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10019</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, par value $0.001 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2025-04-29</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1790</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4716536</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnotes</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Restricted Stock Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F6"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2025-04-29</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1790</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F7"/>
            </exerciseDate>
            <expirationDate>
                <value>2034-09-19</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1790</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnotes</value>
                    <footnoteId id="F8"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Restricted Stock Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F6"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2025-04-29</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1225</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F9"/>
            </exerciseDate>
            <expirationDate>
                <value>2035-04-29</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1225</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1225</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnotes</value>
                    <footnoteId id="F8"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">In addition to Politan Capital Management LP, a Delaware limited partnership (&quot;Politan&quot;), this Form 4 is being filed jointly by Politan Capital Management GP LLC, a Delaware limited liability company (&quot;Politan Management&quot;), Politan Capital Partners GP LLC, a Delaware limited liability company (&quot;Politan GP&quot;), and Quentin Koffey, a citizen of the United States of America (together with Politan, Politan Management and Politan GP, the &quot;Reporting Persons&quot;), each of whom has the same business address as Politan and may be deemed to have a pecuniary interest in securities reported on this Form 4 (the &quot;Subject Securities&quot;).</footnote>
        <footnote id="F2">Politan is the investment advisor to certain funds, including Politan Capital Partners LP, a Delaware limited partnership (&quot;Politan LP&quot;), Politan Capital Offshore Partners LP, a Cayman Islands exempted limited partnership (&quot;Politan Offshore&quot;), and Politan Capital Partners Master Fund LP, a Cayman Islands exempted limited partnership (&quot;Politan Master Fund&quot;) (collectively with Politan Offshore and Politan LP, the &quot;Politan Funds&quot;).</footnote>
        <footnote id="F3">Politan, as the investment advisor of the Politan Funds, may be deemed to be the beneficial owner of the Subject Securities for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1934. As the general partner of Politan, Politan Management may be deemed to be the beneficial owner of the Subject Securities for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1934. As the general partner of the Politan Funds, Politan GP may be deemed to be the beneficial owner of the Subject Securities for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1934.</footnote>
        <footnote id="F4">By virtue of Mr. Koffey's position as managing partner and chief investment officer of Politan, and as the managing member of Politan Management and Politan GP, Mr. Koffey may be deemed to be the beneficial owner of the Subject Securities for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1934. Each of the Reporting Persons disclaims any beneficial ownership of any of the Subject Securities, except to the extent of any pecuniary interest therein.</footnote>
        <footnote id="F5">Mr. Koffey is a member of the board of directors of the Issuer of the Subject Securities, and as a result, each of the other Reporting Persons may be directors by deputization for purposes of Section 16 of the Securities Exchange Act of 1934.</footnote>
        <footnote id="F6">Each restricted stock unit (&quot;RSU&quot;) represents the contingent right to receive one share of Common Stock of the Issuer upon vesting of the RSU.</footnote>
        <footnote id="F7">These RSUs were granted on September 19, 2024 and vested in full on April 29, 2025, the date of the next annual meeting of stockholders following the date of the grant.</footnote>
        <footnote id="F8">These RSUs are held directly by Mr. Koffey.</footnote>
        <footnote id="F9">These RSUs were granted on April 29, 2025 and will vest in full on the earlier of the first anniversary of the grant date or the date of the next annual meeting of stockholders following the grant.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Politan Capital Management LP By: Politan Capital Management GP LLC, its General Partner /s/ Quentin Koffey, Managing Member</signatureName>
        <signatureDate>2025-05-01</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Politan Capital Management GP LLC /s/ Quentin Koffey, Managing Member</signatureName>
        <signatureDate>2025-05-01</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Politan Capital Partners GP LLC /s/ Quentin Koffey, Managing Member</signatureName>
        <signatureDate>2025-05-01</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Quentin Koffey</signatureName>
        <signatureDate>2025-05-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
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</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
