John Edward Williams - 17 Feb 2026 Form 4 Insider Report for MKS INC (MKSI)

Role: EVP & GM, PSD
Signature: /s/ M. Kathryn Rickards, attorney-in-fact
Issuer symbol: MKSI
Transactions as of: 17 Feb 2026
Net transactions value: -$311,711
Form type: 4
Filing time: 18 Feb 2026, 17:00:53 UTC
Previous filing: 09 Feb 2026
Next filing: 23 Feb 2026
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
Williams John Edward	EVP & GM, PSD	C/O MKS INC., 2 TECH DRIVE, ANDOVER	/s/ M. Kathryn Rickards, attorney-in-fact	18 Feb 2026	0001710173

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	MKSI	Common Stock	Options Exercise		+300	+8.3%		3,940	17 Feb 2026	Direct	F1
transaction	MKSI	Common Stock	Options Exercise		+841	+21%		4,781	17 Feb 2026	Direct	F1
transaction	MKSI	Common Stock	Options Exercise		+991	+21%		5,772	17 Feb 2026	Direct	F1
transaction	MKSI	Common Stock	Options Exercise		+1,106	+19%		6,878	17 Feb 2026	Direct	F1
transaction	MKSI	Common Stock	Tax liability	$311,711	-1,195	-17%	$260.74	5,683	17 Feb 2026	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		+1,474	+14%		11,791	17 Feb 2026	Common Stock	1,474		Direct	F1, F3
transaction	MKSI	Restricted Stock Unit	Options Exercise		-300	-2.5%		11,490	17 Feb 2026	Common Stock	300		Direct	F1, F4
transaction	MKSI	Restricted Stock Unit	Options Exercise		-841	-7.3%		10,649	17 Feb 2026	Common Stock	841		Direct	F1, F5
transaction	MKSI	Restricted Stock Unit	Options Exercise		-991	-9.3%		9,659	17 Feb 2026	Common Stock	991		Direct	F1, F6
transaction	MKSI	Restricted Stock Unit	Options Exercise		-1,106	-11%		8,553	17 Feb 2026	Common Stock	1,106		Direct	F1, F7

* 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 Inc.
F2	These shares were withheld by MKS 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, 2027, 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 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.
F5	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.
F6	These RSUs were subject to performance criteria, the achievement of which was determined on February 8, 2026, and thereafter vest in three equal annual installments beginning 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.
F7	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.