MKS INC — Director's Dealing 2026

Feb 18, 2026

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MKS INC (MKSI)
CIK: 0001049502
Period of Report: 2026-02-17

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

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2026-02-17	Common Stock	M	22088.091	—	Acquired	169443.2537	Direct
2026-02-17	Common Stock	M	7653.601	—	Acquired	177096.8547	Direct
2026-02-17	Common Stock	M	3859.12	—	Acquired	180955.9747	Direct
2026-02-17	Common Stock	M	7208	—	Acquired	188163.9747	Direct
2026-02-17	Common Stock	M	16989.44	—	Acquired	205153.4147	Direct
2026-02-17	Common Stock	M	12091	—	Acquired	217244.4147	Direct
2026-02-17	Common Stock	F	32548.307	$260.74	Disposed	184696.1077	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2026-02-17	Restricted Stock Unit	$	A	15592.911	Acquired		Common Stock (15592.911)	Direct
2026-02-17	Restricted Stock Unit	$	M	22088.091	Disposed		Common Stock (22088.091)	Direct
2026-02-17	Restricted Stock Unit	$	M	7653.601	Disposed		Common Stock (7653.601)	Direct
2026-02-17	Restricted Stock Unit	$	M	3859.12	Disposed		Common Stock (3859.12)	Direct
2026-02-17	Restricted Stock Unit	$	M	7208	Disposed		Common Stock (7208)	Direct
2026-02-17	Restricted Stock Unit	$	M	16989.44	Disposed		Common Stock (16989.44)	Direct
2026-02-17	Restricted Stock Unit	$	M	12091	Disposed		Common Stock (12091)	Direct

Footnotes

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 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.

F5: 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.

F6: 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.

F7: 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.

F8: 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.

F9: 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.