MKS INC — Director's Dealing 2025

Feb 19, 2025

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MKS INSTRUMENTS INC (MKSI)
CIK: 0001049502
Period of Report: 2025-02-18

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

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2025-02-18	Common Stock	M	14041.44	—	Acquired	126729.9897	Direct
2025-02-18	Common Stock	M	6735.326	—	Acquired	133465.3157	Direct
2025-02-18	Common Stock	M	22088	—	Acquired	155553.3157	Direct
2025-02-18	Common Stock	M	7654	—	Acquired	163207.3157	Direct
2025-02-18	Common Stock	M	4035.12	—	Acquired	167242.4357	Direct
2025-02-18	Common Stock	M	7207	—	Acquired	174449.4357	Direct
2025-02-18	Common Stock	F	27332	$103.67	Disposed	147117.4357	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2025-02-18	Restricted Stock Unit	$	A	37925.476	Acquired		Common Stock (37925.476)	Direct
2025-02-18	Restricted Stock Unit	$	M	14041.44	Disposed		Common Stock (14041.44)	Direct
2025-02-18	Restricted Stock Unit	$	M	6735.326	Disposed		Common Stock (6735.326)	Direct
2025-02-18	Restricted Stock Unit	$	M	22088	Disposed		Common Stock (22088)	Direct
2025-02-18	Restricted Stock Unit	$	M	7654	Disposed		Common Stock (7654)	Direct
2025-02-18	Restricted Stock Unit	$	M	4035.12	Disposed		Common Stock (4035.12)	Direct
2025-02-18	Restricted Stock Unit	$	M	7207	Disposed		Common Stock (7207)	Direct

Footnotes

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.