116 transactions on file (0 open-market purchases and 49 open-market sales).
49 open-market sales by MKSI insiders, between Sep 18, 2025 and Sep 1, 2026. A sale made under a trading plan agreed months earlier is not the same event as one decided that week, and the filing itself says which.
Discretionary. The box was on the form and was not ticked. The sale was made at the prevailing price without a pre-arranged plan behind it.
Planned (10b5-1). The filer ticked the Form 4's 10b5-1 box: the sale ran under a trading plan adopted before the trade, so it is a schedule executing rather than a view taken this week.
Not stated. The filing does not say. Either it predates the April 2023 checkbox, or nothing has re-read it since. This tab will not guess which of the two above it was.
| Date | Insider | Type | Shares | Price | Value | Owned after |
|---|---|---|---|---|---|---|
| 2026-09-01 | Mora Elizabeth Director Open-market salePlanned (10b5-1) | Open-market sale Planned (10b5-1) | −300 | $250.96 | −75.29K | 18,845.353 |
| 2026-08-14 | Lee John Tseng-Chung President & CEO · Director Open-market salePlanned (10b5-1) | Open-market sale Planned (10b5-1) | −10,000 | $302.01 | −3.02M | 134,776.2667 |
| 2026-08-03 | Williams John Edward EVP & GM, PSD Open-market salePlanned (10b5-1) | Open-market sale Planned (10b5-1) | −457 | $288.31 | −131.76K | 4,097.844 |
| 2026-06-12 | Schreiner James Alan EVP & COO Open-market saleDiscretionary | Open-market sale Discretionary | −2,471 | $345.52 | −853.79K | 20,230.121 |
| 2026-06-12 | Schreiner James Alan EVP & COO Open-market saleDiscretionary | Open-market sale Discretionary | −812 | $346.41 | −281.28K | 19,418.121 |
111 more transactions are on Measure
| Insider | Role | On Sep 11, 2025 | Now | Change | Sold | Shape |
|---|---|---|---|---|---|---|
| Mayampurath RamakumarEVP & CFO | EVP & CFO | 8,811.139 | 1.139 | −99.99% | $2.78M$2.78M on a plan | |
| McCarthy Michelle MVP & Chief Accounting Officer | VP & Chief Accounting Officer | 1,466 | 1.549 | −99.89% | $1.13M$366.5K no plan · $767.27K on a plan | |
| COLELLA GERALD GDirector | Director | 60,017 | 20,017 | −66.65% | $11.74M$5.07M no plan · $6.67M on a plan |
10 more insiders, included withMeasure
Each person’s holding as they reported it after each open-market trade, over the last twelve months. It counts one class of stock and excludes grants, option exercises and shares withheld for tax, so a stake can fall here while somebody’s total holding does not. Since April 2023 a Form 4 states whether a trade ran under a pre-arranged 10b5-1 plan; an older one does not, and those dollars read “not stated” rather than being counted either way.
The assistant answers from what MKSI has actually filed: 18 annual reports filed with the SEC, 116 Form 4 filings from the last year, 13F positions from the 1 tracked investor who hold it and 4 funds that hold it. Every figure in a reply links to the filing it came from, so an answer can be checked rather than believed.
Pressing one answers it here, from MKSI's filings and figures. One a day without an account; a free account has its own, and no card.
See every Form 4 MKSI insiders have filed, not the latest few.
Ten seconds, no card, and nothing to cancel.
Source
From SEC Form 4 filings, filed by officers, directors and 10%-owners within two business days of a transaction. “Indirect” holdings (a trust, an LLC, a family member) are included and not distinguished from direct ones in this table.
Past transactions say nothing about future ones, and none of this is investment advice.
See who bought, not who was handed shares
Every Form 4 MKSI insiders file, not just the latest handful, with vesting and tax withholding struck out so what's left reads as a decision.
Every filingMeasure
Follow the investors who hold it
Each stake priced at the quarter it was filed, and diffed against the quarter before: who added, who trimmed, who left.
Every position they holdMeasure
Ask what a run of filings adds up to
Whether this is one decision or a pattern, and how it compares with MKSI's own history of insider activity.
Free, no card, and it does not expire.