<SEC-DOCUMENT>0001950047-25-008368.txt : 20251103
<SEC-HEADER>0001950047-25-008368.hdr.sgml : 20251103
<ACCEPTANCE-DATETIME>20251103160937
ACCESSION NUMBER:		0001950047-25-008368
CONFORMED SUBMISSION TYPE:	144
PUBLIC DOCUMENT COUNT:		1
FILED AS OF DATE:		20251103
DATE AS OF CHANGE:		20251103

SUBJECT COMPANY:	

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Merck & Co., Inc.
		CENTRAL INDEX KEY:			0000310158
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		ORGANIZATION NAME:           	03 Life Sciences
		EIN:				221918501
		STATE OF INCORPORATION:			NJ
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		144
		SEC ACT:		1933 Act
		SEC FILE NUMBER:	001-06571
		FILM NUMBER:		251444164

	BUSINESS ADDRESS:	
		STREET 1:		126 EAST LINCOLN AVENUE
		STREET 2:		P.O. BOX 2000
		CITY:			RAHWAY
		STATE:			NJ
		ZIP:			07065
		BUSINESS PHONE:		908-740-4000

	MAIL ADDRESS:	
		STREET 1:		126 EAST LINCOLN AVENUE
		STREET 2:		P.O. BOX 2000
		CITY:			RAHWAY
		STATE:			NJ
		ZIP:			07065

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	Merck & Co. Inc.
		DATE OF NAME CHANGE:	20091103

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	SCHERING PLOUGH CORP
		DATE OF NAME CHANGE:	19920703

REPORTING-OWNER:	

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Williams David Michael
		CENTRAL INDEX KEY:			0001820958
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		144

	MAIL ADDRESS:	
		STREET 1:		MERCK & CO., INC.
		STREET 2:		126 EAST LINCOLN AVENUE
		CITY:			RAHWAY
		STATE:			NJ
		ZIP:			07065
</SEC-HEADER>
<DOCUMENT>
<TYPE>144
<SEQUENCE>1
<FILENAME>primary_doc.xml
<TEXT>
<XML>
<?xml version="1.0" encoding="UTF-8"?><edgarSubmission xmlns="http://www.sec.gov/edgar/ownership" xmlns:ns2="http://www.sec.gov/edgar/common">
    <headerData>
        <submissionType>144</submissionType>
        <filerInfo>
            <filer>
                <filerCredentials>
                    <cik>0001820958</cik>
                    <ccc>XXXXXXXX</ccc>
                </filerCredentials>
            </filer>
            <liveTestFlag>LIVE</liveTestFlag>



        </filerInfo>
    </headerData>
    <formData>
        <issuerInfo>
            <issuerCik>0000310158</issuerCik>
            <issuerName>MERCK &amp; CO. INC.</issuerName>
            <secFileNumber>001-06571</secFileNumber>
            <issuerAddress>
                <ns2:street1>126 East Lincoln Avenue</ns2:street1>
                <ns2:city>Rahway</ns2:city>
                <ns2:stateOrCountry>NJ</ns2:stateOrCountry>
                <ns2:zipCode>07065</ns2:zipCode>
            </issuerAddress>
            <issuerContactPhone>(732) 594-4000</issuerContactPhone>
            <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>DAVID WILLIAMS</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
            <relationshipsToIssuer>
                <relationshipToIssuer>Officer</relationshipToIssuer>
            </relationshipsToIssuer>
        </issuerInfo>
        <securitiesInformation>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <brokerOrMarketmakerDetails>
                <name>Morgan Stanley Smith Barney LLC Executive Financial Services</name>
                <address>
                    <ns2:street1>1 New York Plaza</ns2:street1>
                    <ns2:street2>8th Floor</ns2:street2>
                    <ns2:city>New York</ns2:city>
                    <ns2:stateOrCountry>NY</ns2:stateOrCountry>
                    <ns2:zipCode>10004</ns2:zipCode>
                </address>
            </brokerOrMarketmakerDetails>
            <noOfUnitsSold>8614</noOfUnitsSold>
            <aggregateMarketValue>720039.95</aggregateMarketValue>
            <noOfUnitsOutstanding>2497783211</noOfUnitsOutstanding>
            <approxSaleDate>11/03/2025</approxSaleDate>
            <securitiesExchangeName>NYSE</securitiesExchangeName>
        </securitiesInformation>
        <securitiesToBeSold>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <acquiredDate>01/22/2024</acquiredDate>
            <natureOfAcquisitionTransaction>Restricted stock vesting under a registered plan</natureOfAcquisitionTransaction>
            <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
            <isGiftTransaction>N</isGiftTransaction>
            <amountOfSecuritiesAcquired>4195</amountOfSecuritiesAcquired>
            <paymentDate>01/22/2024</paymentDate>
            <natureOfPayment>Not Applicable</natureOfPayment>
        </securitiesToBeSold>
        <securitiesToBeSold>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <acquiredDate>01/23/2023</acquiredDate>
            <natureOfAcquisitionTransaction>Restricted stock vesting under a registered plan</natureOfAcquisitionTransaction>
            <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
            <isGiftTransaction>N</isGiftTransaction>
            <amountOfSecuritiesAcquired>294</amountOfSecuritiesAcquired>
            <paymentDate>01/23/2020</paymentDate>
            <natureOfPayment>Not Applicable</natureOfPayment>
        </securitiesToBeSold>
        <securitiesToBeSold>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <acquiredDate>05/01/2022</acquiredDate>
            <natureOfAcquisitionTransaction>Restricted stock vesting under a registered plan</natureOfAcquisitionTransaction>
            <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
            <isGiftTransaction>N</isGiftTransaction>
            <amountOfSecuritiesAcquired>379</amountOfSecuritiesAcquired>
            <paymentDate>05/01/2022</paymentDate>
            <natureOfPayment>Not Applicable</natureOfPayment>
        </securitiesToBeSold>
        <securitiesToBeSold>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <acquiredDate>01/09/2024</acquiredDate>
            <natureOfAcquisitionTransaction>Restricted stock vesting under a registered plan</natureOfAcquisitionTransaction>
            <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
            <isGiftTransaction>N</isGiftTransaction>
            <amountOfSecuritiesAcquired>2</amountOfSecuritiesAcquired>
            <paymentDate>01/09/2024</paymentDate>
            <natureOfPayment>Not Applicable</natureOfPayment>
        </securitiesToBeSold>
        <securitiesToBeSold>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <acquiredDate>02/24/2022</acquiredDate>
            <natureOfAcquisitionTransaction>Restricted stock vesting under a registered plan</natureOfAcquisitionTransaction>
            <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
            <isGiftTransaction>N</isGiftTransaction>
            <amountOfSecuritiesAcquired>1507</amountOfSecuritiesAcquired>
            <paymentDate>02/24/2022</paymentDate>
            <natureOfPayment>Not Applicable</natureOfPayment>
        </securitiesToBeSold>
        <securitiesToBeSold>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <acquiredDate>05/03/2022</acquiredDate>
            <natureOfAcquisitionTransaction>Restricted stock vesting under a registered plan</natureOfAcquisitionTransaction>
            <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
            <isGiftTransaction>N</isGiftTransaction>
            <amountOfSecuritiesAcquired>280</amountOfSecuritiesAcquired>
            <paymentDate>05/03/2022</paymentDate>
            <natureOfPayment>Not Applicable</natureOfPayment>
        </securitiesToBeSold>
        <securitiesToBeSold>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <acquiredDate>02/10/2023</acquiredDate>
            <natureOfAcquisitionTransaction>Restricted stock vesting under a registered plan</natureOfAcquisitionTransaction>
            <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
            <isGiftTransaction>N</isGiftTransaction>
            <amountOfSecuritiesAcquired>792</amountOfSecuritiesAcquired>
            <paymentDate>02/10/2023</paymentDate>
            <natureOfPayment>Not Applicable</natureOfPayment>
        </securitiesToBeSold>
        <securitiesToBeSold>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <acquiredDate>05/01/2023</acquiredDate>
            <natureOfAcquisitionTransaction>Restricted stock vesting under a registered plan</natureOfAcquisitionTransaction>
            <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
            <isGiftTransaction>N</isGiftTransaction>
            <amountOfSecuritiesAcquired>379</amountOfSecuritiesAcquired>
            <paymentDate>05/01/2023</paymentDate>
            <natureOfPayment>Not Applicable</natureOfPayment>
        </securitiesToBeSold>
        <securitiesToBeSold>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <acquiredDate>04/13/2023</acquiredDate>
            <natureOfAcquisitionTransaction>Restricted stock vesting under a registered plan</natureOfAcquisitionTransaction>
            <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
            <isGiftTransaction>N</isGiftTransaction>
            <amountOfSecuritiesAcquired>61</amountOfSecuritiesAcquired>
            <paymentDate>04/13/2023</paymentDate>
            <natureOfPayment>Not Applicable</natureOfPayment>
        </securitiesToBeSold>
        <securitiesToBeSold>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <acquiredDate>02/10/2022</acquiredDate>
            <natureOfAcquisitionTransaction>Restricted stock vesting under a registered plan</natureOfAcquisitionTransaction>
            <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
            <isGiftTransaction>N</isGiftTransaction>
            <amountOfSecuritiesAcquired>725</amountOfSecuritiesAcquired>
            <paymentDate>02/10/2022</paymentDate>
            <natureOfPayment>Not Applicable</natureOfPayment>
        </securitiesToBeSold>
        <nothingToReportFlagOnSecuritiesSoldInPast3Months>Y</nothingToReportFlagOnSecuritiesSoldInPast3Months>
        <noticeSignature>
            <noticeDate>11/03/2025</noticeDate>
            <planAdoptionDates/>
            <signature>/s/ David Michael Williams</signature>
        </noticeSignature>
    </formData>
</edgarSubmission>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
