X0609 4 2026-05-11 0001049502 MKS INC MKSI 0001256715 COLELLA GERALD G false C/O MKS INC. 2 TECH DRIVE ANDOVER MA 01810 1 0 Common Stock 2026-05-11 4 A 0 781.959 A 8998.886 D Common Stock 40017 I By The Gerald G. Colella 2019 Trust These restricted stock units become fully vested on the day prior to the first annual meeting of shareholders following the date of grant (or if no such meeting is held within 13 months after the date of grant, on the 13 month anniversary of the date of grant). Each restricted stock unit represents the contingent right to receive one share of common stock of MKS Inc. /s/ M. Kathryn Rickards, attorney-in-fact 2026-05-12