MKS INC — Director's Dealing 2025

Nov 4, 2025

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MKS INC (MKSI)
CIK: 0001049502
Period of Report: 2025-10-31

Reporting Person: Burke Kathleen Flaherty (EVP, GC & Secretary)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2025-10-31	Common Stock	M	158	—	Acquired	51232.509	Direct
2025-10-31	Common Stock	M	52	—	Acquired	51284.509	Direct
2025-10-31	Common Stock	M	82	—	Acquired	51366.509	Direct
2025-10-31	Common Stock	M	144	—	Acquired	51510.509	Direct
2025-10-31	Common Stock	M	341	—	Acquired	51851.509	Direct
2025-10-31	Common Stock	F	777	$143.71	Disposed	51074.509	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2025-10-31	Restricted Stock Unit	$	M	158	Disposed		Common Stock (158)	Direct
2025-10-31	Restricted Stock Unit	$	M	52	Disposed		Common Stock (52)	Direct
2025-10-31	Restricted Stock Unit	$	M	82	Disposed		Common Stock (82)	Direct
2025-10-31	Restricted Stock Unit	$	M	144	Disposed		Common Stock (144)	Direct
2025-10-31	Restricted Stock Unit	$	M	341	Disposed		Common Stock (341)	Direct

Footnotes

F1: Each restricted stock unit (RSU) represents the contingent right to receive one share of common stock of MKS Inc.

F2: Shares used to satisfy FICA taxes.

F3: Portion of 2023 RSU Award accelerated to satisfy FICA taxes.

F4: Portion of 2024 RSU Award accelerated to satisfy FICA taxes.

F5: Portion of 2025 RSU Award accelerated to satisfy FICA taxes.