Kathleen Flaherty Burke - 28 Oct 2021 Form 4 Insider Report for MKS INSTRUMENTS INC (MKSI)

Role: Sr. VP, GC & Secretary
Signature: /s/ M. Kathryn Rickards, attorney-in-fact
Issuer symbol: MKSI
Transactions as of: 28 Oct 2021
Net transactions value: -$140,931
Form type: 4
Filing time: 29 Oct 2021, 17:23:24 UTC
Next filing: 24 Jan 2022
SEC: View on sec.gov

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	MKSI	Common Stock	Options Exercise		+2,179	+5.5%		41,699	28 Oct 2021	Direct	F1
transaction	MKSI	Common Stock	Tax liability	$140,931	-967	-2.3%	$145.74	40,732	28 Oct 2021	Direct	F2

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Underlying Class	Amount	Exercise Price	Ownership	Footnotes
transaction	MKSI	Restricted Stock Unit	Options Exercise		-2,179	-13%		14,344	28 Oct 2021	Common Stock	2,179		Direct	F1, F3

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	Each restricted stock unit represents the contingent right to receive one share of common stock of MKS Instruments, Inc.
F2	This transaction was effected pursuant to a Rule 10b5-1 trading plan previously adopted by the reporting person.
F3	These RSUs vest in two equal annual installments on each of the second anniversary and third anniversary of the date of grant, October 28, 2019.