<SEC-DOCUMENT>0001193125-21-095394-index.html : 20210326
<SEC-HEADER>0001193125-21-095394.hdr.sgml : 20210326
<ACCEPTANCE-DATETIME>20210326080129
ACCESSION NUMBER:		0001193125-21-095394
CONFORMED SUBMISSION TYPE:	DEFA14A
PUBLIC DOCUMENT COUNT:		3
FILED AS OF DATE:		20210326
DATE AS OF CHANGE:		20210326

FILER:

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

	FILING VALUES:
		FORM TYPE:		DEFA14A
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-23621
		FILM NUMBER:		21774761

	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
</SEC-HEADER>
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<TYPE>DEFA14A
<SEQUENCE>1
<FILENAME>d104095ddefa14a.htm
<DESCRIPTION>DEFA14A
<TEXT>
Document 1 - file: d104095ddefa14a.htm

</DOCUMENT>
<DOCUMENT>
<TYPE>GRAPHIC
<SEQUENCE>2
<FILENAME>g104095dsp003.jpg
<DESCRIPTION>GRAPHIC
<TEXT>
Document 2 - file: g104095dsp003.jpg

</DOCUMENT>
<DOCUMENT>
<TYPE>GRAPHIC
<SEQUENCE>3
<FILENAME>g104095dsp004.jpg
<DESCRIPTION>GRAPHIC
<TEXT>
Document 3 - file: g104095dsp004.jpg

</DOCUMENT>
</SEC-DOCUMENT>