X0508 4 2026-02-17 0001049502 MKS INC MKSI 0001842235 Taranto Eric Robert C/O MKS INC. 2 TECH DRIVE ANDOVER MA 01810 1 EVP & GM, VSD 0 Common Stock 2026-02-17 4 M 0 1764.153 A 19468.4004 D Common Stock 2026-02-17 4 M 0 914.048 A 20382.4484 D Common Stock 2026-02-17 4 M 0 348.33 A 20730.7784 D Common Stock 2026-02-17 4 M 0 976 A 21706.7784 D Common Stock 2026-02-17 4 M 0 1167.36 A 22874.1384 D Common Stock 2026-02-17 4 M 0 1303 A 24177.1384 D Common Stock 2026-02-17 4 F 0 2711.768 260.74 D 21465.3704 D Restricted Stock Unit 2026-02-17 4 A 0 1758.956 A Common Stock 1758.956 14501.557 D Restricted Stock Unit 2026-02-17 4 M 0 1764.153 D Common Stock 1764.153 12737.404 D Restricted Stock Unit 2026-02-17 4 M 0 914.048 D Common Stock 914.048 11823.356 D Restricted Stock Unit 2026-02-17 4 M 0 348.33 D Common Stock 348.33 11475.026 D Restricted Stock Unit 2026-02-17 4 M 0 976 D Common Stock 976 10499.026 D Restricted Stock Unit 2026-02-17 4 M 0 1167.36 D Common Stock 1167.36 9331.666 D Restricted Stock Unit 2026-02-17 4 M 0 1303 D Common Stock 1303 8028.666 D Each restricted stock unit (RSU) represents the contingent right to receive one share of common stock of MKS Inc. 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. 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. 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. 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. 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. 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. 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. 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. /s/ M. Kathryn Rickards, attorney-in-fact 2026-02-18