COLELLA GERALD G 4

What Happened

• Gerald G. Colella, a director of MKS Inc. (MKSI), reported multiple open‑market sales on May 27, 2026 totaling 20,000 shares for aggregate proceeds of approximately $6,668,076. Reported lots: 464 @ $330.38 ($153,298); 8,210 @ $331.45 ($2,721,195); 4,876 @ $332.04 ($1,619,034); 1,811 @ $335.46 ($607,514); 1,626 @ $336.54 ($547,219); 213 @ $337.05 ($71,792); and 2,800 @ $338.58 ($948,024). These are sales (not purchases).

Key Details

• Transaction date: May 27, 2026 (Period of Report: 2026-05-27); filing date: May 28, 2026 (timely).
• Price information: Filing reports weighted‑average prices for each lot; footnotes indicate many trades were executed in multiple fills at price ranges (examples across lots: ~$329.90–$337.73).
• Plan/authorization: Filing includes a footnote that the trades were effected pursuant to a Rule 10b5‑1 trading plan adopted Feb 24, 2026.
• Shares owned after the transaction: not stated in this Form 4 filing.
• Filing timeliness: filed the next day (no late‑filing flag indicated).

Context

• These are pre‑arranged open‑market sales under a 10b5‑1 plan, which means the trades were scheduled in advance and are generally considered routine; sales do not necessarily reflect the director’s current view of the company. Purchases are typically more informative about insider sentiment; this filing documents realized dispositions.