Kathleen Flaherty Burke - 18 Feb 2025 Form 4 Insider Report for MKS INSTRUMENTS INC (MKSI)

Role: EVP, GC & Secretary
Signature: /s/ M. Kathryn Rickards, attorney-in-fact
Issuer symbol: MKSI
Transactions as of: 18 Feb 2025
Net transactions value: -$411,570
Form type: 4
Filing time: 19 Feb 2025, 18:24:46 UTC
Previous filing: 11 Feb 2025
Next filing: 04 Nov 2025
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		+2,287	+5.3%		45,533	18 Feb 2025	Direct	F1
transaction	MKSI	Common Stock	Options Exercise		+1,645	+3.6%		47,178	18 Feb 2025	Direct	F1
transaction	MKSI	Common Stock	Options Exercise		+3,608	+7.6%		50,786	18 Feb 2025	Direct	F1
transaction	MKSI	Common Stock	Options Exercise		+1,870	+3.7%		52,656	18 Feb 2025	Direct	F1
transaction	MKSI	Common Stock	Options Exercise		+588	+1.1%		53,244	18 Feb 2025	Direct	F1
transaction	MKSI	Common Stock	Options Exercise		+1,648	+3.1%		54,892	18 Feb 2025	Direct	F1
transaction	MKSI	Common Stock	Tax liability	$411,570	-3,970	-7.2%	$103.67	50,922	18 Feb 2025	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	Award		+7,822	+36%		29,422	18 Feb 2025	Common Stock	7,822		Direct	F1, F3
transaction	MKSI	Restricted Stock Unit	Options Exercise		-2,287	-7.8%		27,135	18 Feb 2025	Common Stock	2,287		Direct	F1, F4
transaction	MKSI	Restricted Stock Unit	Options Exercise		-1,645	-6.1%		25,490	18 Feb 2025	Common Stock	1,645		Direct	F1, F5
transaction	MKSI	Restricted Stock Unit	Options Exercise		-3,608	-14%		21,882	18 Feb 2025	Common Stock	3,608		Direct	F1, F6
transaction	MKSI	Restricted Stock Unit	Options Exercise		-1,870	-8.5%		20,012	18 Feb 2025	Common Stock	1,870		Direct	F1, F7
transaction	MKSI	Restricted Stock Unit	Options Exercise		-588	-2.9%		19,424	18 Feb 2025	Common Stock	588		Direct	F1, F8
transaction	MKSI	Restricted Stock Unit	Options Exercise		-1,648	-8.5%		17,776	18 Feb 2025	Common Stock	1,648		Direct	F1, F9

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

Explanation of Responses:

Id	Content
F1	Each restricted stock unit (RSU) represents the contingent right to receive one share of common stock of MKS Instruments, Inc.
F2	These shares were withheld by MKS Instruments, Inc. to satisfy the tax withholding obligations triggered by the vesting of RSUs and do not represent a discretionary trade by the reporting person.
F3	These RSUs vest in three equal annual installments commencing on February 15, 2026, provided that if, in any vesting year, February 15th is not a business day, such vesting shall occur on the next business day.
F4	These RSUs were subject to performance criteria, the achievement of which was determined on February 8, 2023, and thereafter vest in three equal annual installments beginning on February 15, 2023, provided that if, in any vesting year, February 15th is not a business day, such vesting shall occur on the next business day.
F5	These RSUs vest in three equal annual installments commencing on February 15, 2023, provided that if, in any vesting year, February 15th is not a business day, such vesting shall occur on the next business day.
F6	These RSUs were subject to performance criteria, the achievement of which was determined on February 5, 2024, and thereafter vest in three equal annual installments beginning on February 15, 2024, provided that if, in any vesting year, February 15th is not a business day, such vesting shall occur on the next business day.
F7	These RSUs vest in three equal annual installments commencing on February 15, 2024, provided that if, in any vesting year, February 15th is not a business day, such vesting shall occur on the next business day.
F8	These RSUs were subject to performance criteria, the achievement of which was determined on February 10, 2025, and thereafter vest in three equal annual installments beginning on February 15, 2025, provided that if, in any vesting year, February 15th is not a business day, such vesting shall occur on the next business day.
F9	These RSUs vest in three equal annual installments commencing on February 15, 2025, provided that if, in any vesting year, February 15th is not a business day, such vesting shall occur on the next business day.