<SEC-DOCUMENT>0002007317-25-000158.txt : 20250218
<SEC-HEADER>0002007317-25-000158.hdr.sgml : 20250218
<ACCEPTANCE-DATETIME>20250218135924
ACCESSION NUMBER:		0002007317-25-000158
CONFORMED SUBMISSION TYPE:	144
PUBLIC DOCUMENT COUNT:		1
FILED AS OF DATE:		20250218
DATE AS OF CHANGE:		20250218

SUBJECT COMPANY:	

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MKS INSTRUMENTS INC
		CENTRAL INDEX KEY:			0001049502
		STANDARD INDUSTRIAL CLASSIFICATION:	INDUSTRIAL INSTRUMENTS FOR MEASUREMENT, DISPLAY, AND CONTROL [3823]
		ORGANIZATION NAME:           	08 Industrial Applications and Services
		IRS NUMBER:				042277512
		STATE OF INCORPORATION:			MA
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		144
		SEC ACT:		1933 Act
		SEC FILE NUMBER:	000-23621
		FILM NUMBER:		25634200

	BUSINESS ADDRESS:	
		STREET 1:		2 TECH DRIVE
		STREET 2:		SUITE 201
		CITY:			ANDOVER
		STATE:			MA
		ZIP:			01810
		BUSINESS PHONE:		978-645-5500

	MAIL ADDRESS:	
		STREET 1:		2 TECH DRIVE
		STREET 2:		SUITE 201
		CITY:			ANDOVER
		STATE:			MA
		ZIP:			01810

REPORTING-OWNER:	

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			COLELLA GERARD G
		CENTRAL INDEX KEY:			0001256715
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		144

	MAIL ADDRESS:	
		STREET 1:		6 SHATTUCK RD
		CITY:			ANDOVER
		STATE:			MA
		ZIP:			01810
</SEC-HEADER>
<DOCUMENT>
<TYPE>144
<SEQUENCE>1
<FILENAME>primary_doc.xml
<TEXT>
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<?xml version="1.0" encoding="UTF-8"?><edgarSubmission xmlns="http://www.sec.gov/edgar/ownership" xmlns:com="http://www.sec.gov/edgar/common">
  <headerData>
    <submissionType>144</submissionType>
    <filerInfo>
      <filer>
        <filerCredentials>
          <cik>0001256715</cik>
          <ccc>XXXXXXXX</ccc>
        </filerCredentials>
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      <liveTestFlag>LIVE</liveTestFlag>



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  <formData>
    <issuerInfo>
      <issuerCik>0001049502</issuerCik>
      <issuerName>MKS INSTRUMENTS INC</issuerName>
      <secFileNumber>000-23621</secFileNumber>
      <issuerAddress>
        <com:street1>2 TECH DRIVE</com:street1>
        <com:street2>SUITE 201</com:street2>
        <com:city>ANDOVER</com:city>
        <com:stateOrCountry>MA</com:stateOrCountry>
        <com:zipCode>01810</com:zipCode>
      </issuerAddress>
      <issuerContactPhone>978-645-5500</issuerContactPhone>
      <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>COLELLA GERARD G</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
      <relationshipsToIssuer>
        <relationshipToIssuer>Director</relationshipToIssuer>
      </relationshipsToIssuer>
    </issuerInfo>
    <securitiesInformation>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <brokerOrMarketmakerDetails>
        <name>Merrill</name>
        <address>
          <com:street1>100 Federal St</com:street1>
          <com:street2>12th Fl</com:street2>
          <com:city>Boston</com:city>
          <com:stateOrCountry>MA</com:stateOrCountry>
          <com:zipCode>02110</com:zipCode>
        </address>
      </brokerOrMarketmakerDetails>
      <noOfUnitsSold>8000</noOfUnitsSold>
      <aggregateMarketValue>836224.56</aggregateMarketValue>
      <noOfUnitsOutstanding>67298941</noOfUnitsOutstanding>
      <approxSaleDate>02/18/2025</approxSaleDate>
      <securitiesExchangeName>Nasdaq</securitiesExchangeName>
    </securitiesInformation>
    <securitiesToBeSold>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <acquiredDate>08/01/2022</acquiredDate>
      <natureOfAcquisitionTransaction>Stock grant</natureOfAcquisitionTransaction>
      <nameOfPersonfromWhomAcquired>MKS Instruments Inc.</nameOfPersonfromWhomAcquired>
      <isGiftTransaction>N</isGiftTransaction>
      <amountOfSecuritiesAcquired>1000</amountOfSecuritiesAcquired>
      <paymentDate>08/01/2022</paymentDate>
      <natureOfPayment>Cashless</natureOfPayment>
    </securitiesToBeSold>
    <securitiesToBeSold>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <acquiredDate>05/09/2022</acquiredDate>
      <natureOfAcquisitionTransaction>Stock grant</natureOfAcquisitionTransaction>
      <nameOfPersonfromWhomAcquired>MKS Instruments Inc.</nameOfPersonfromWhomAcquired>
      <isGiftTransaction>N</isGiftTransaction>
      <amountOfSecuritiesAcquired>1146</amountOfSecuritiesAcquired>
      <paymentDate>05/09/2022</paymentDate>
      <natureOfPayment>Cashless</natureOfPayment>
    </securitiesToBeSold>
    <securitiesToBeSold>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <acquiredDate>07/02/2020</acquiredDate>
      <natureOfAcquisitionTransaction>Stock grant</natureOfAcquisitionTransaction>
      <nameOfPersonfromWhomAcquired>MKS Instruments Inc.</nameOfPersonfromWhomAcquired>
      <isGiftTransaction>N</isGiftTransaction>
      <amountOfSecuritiesAcquired>1816</amountOfSecuritiesAcquired>
      <paymentDate>07/02/2020</paymentDate>
      <natureOfPayment>Cashless</natureOfPayment>
    </securitiesToBeSold>
    <securitiesToBeSold>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <acquiredDate>02/15/2020</acquiredDate>
      <natureOfAcquisitionTransaction>Stock grant</natureOfAcquisitionTransaction>
      <nameOfPersonfromWhomAcquired>MKS Instruments Inc.</nameOfPersonfromWhomAcquired>
      <isGiftTransaction>N</isGiftTransaction>
      <amountOfSecuritiesAcquired>4038</amountOfSecuritiesAcquired>
      <paymentDate>02/15/2020</paymentDate>
      <natureOfPayment>Cashless</natureOfPayment>
    </securitiesToBeSold>
    <nothingToReportFlagOnSecuritiesSoldInPast3Months>Y</nothingToReportFlagOnSecuritiesSoldInPast3Months>
    <noticeSignature>
      <noticeDate>02/18/2025</noticeDate>
      <signature>Gerald Colella</signature>
    </noticeSignature>
  </formData>
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</SEC-DOCUMENT>
