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: Lee John Tseng-Chung (Director, President & CEO)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2025-10-31	Common Stock	M	352	—	Acquired	147621.5227	Direct
2025-10-31	Common Stock	M	1651	—	Acquired	149272.5227	Direct
2025-10-31	Common Stock	F	2003	$143.71	Disposed	147269.5227	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2025-10-31	Restricted Stock Unit	$	M	352	Disposed		Common Stock (352)	Direct
2025-10-31	Restricted Stock Unit	$	M	1651	Disposed		Common Stock (1651)	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 2024 RSU Award accelerated to satisfy FICA taxes.

F4: Portion of 2025 RSU Award accelerated to satisfy FICA taxes.