MKSI
MKS Instruments Inc
NASDAQ: MKSI · TECHNOLOGY · SCIENTIFIC & TECHNICAL INSTRUMENTS
$218.24
+2.87% today
Updated 2026-10-28
Market cap
$15.45B
P/E ratio
36.33
P/S ratio
3.56x
EPS (TTM)
$6.29
Dividend yield
0.40%
52W range
$130 – $447
Volume
1.3M
MKS Instruments Inc (MKSI) Insider transactions
Net insider activity
Net selling (147,912 shares)
Buy transactions
31
Sell transactions
69
All transactions
| Date | Insider | Title | Type | Shares | Price | Value |
|---|---|---|---|---|---|---|
| 2026-09-01 | MORA, ELIZABETH | Director | Sale | 300 | $250.96 | $75288.00 |
| 2026-08-17 | DONLAN, RENEE MARTEL | EVP, GC & CCO | Buy | 954 | — | — |
| 2026-08-14 | LEE, JOHN TSENG-CHUNG | Director, President & CEO | Sale | 10,000 | $302.01 | $3.02M |
| 2026-08-03 | WILLIAMS, JOHN EDWARD | EVP & GM, PSD | Sale | 457 | $288.31 | $131757.67 |
| 2026-06-12 | SCHREINER, JAMES ALAN | EVP & COO | Sale | 2,471 | $345.52 | $853789.56 |
| 2026-06-12 | SCHREINER, JAMES ALAN | EVP & COO | Sale | 812 | $346.41 | $281281.51 |
| 2026-06-12 | SCHREINER, JAMES ALAN | EVP & COO | Sale | 217 | $347.00 | $75299.00 |
| 2026-06-10 | SCHREINER, JAMES ALAN | EVP & COO | Sale | 781 | $317.42 | $247905.02 |
| 2026-06-05 | MCCARTHY, MICHELLE M | SVP & Chief Accounting Officer | Sale | 2,434 | $315.23 | $767269.82 |
| 2026-06-01 | MORA, ELIZABETH | Director | Sale | 300 | $318.02 | $95406.00 |
| 2026-06-01 | HENRY, DAVID PHILIP | EVP, Global Str Mktg & GM, MSD | Sale | 6,000 | $314.43 | $1.89M |
| 2026-05-27 | DONAHUE, JOSEPH B | Director | Sale | 2,100 | $327.95 | $688703.40 |
| 2026-05-27 | COLELLA, GERALD G | Director | Sale | 8,210 | $331.45 | $2.72M |
| 2026-05-27 | COLELLA, GERALD G | Director | Sale | 4,876 | $332.04 | $1.62M |
| 2026-05-27 | COLELLA, GERALD G | Director | Sale | 2,800 | $338.58 | $948024.00 |
| 2026-05-27 | COLELLA, GERALD G | Director | Sale | 1,811 | $335.46 | $607514.44 |
| 2026-05-27 | COLELLA, GERALD G | Director | Sale | 1,626 | $336.54 | $547218.76 |
| 2026-05-27 | COLELLA, GERALD G | Director | Sale | 464 | $330.38 | $153297.62 |
| 2026-05-27 | COLELLA, GERALD G | Director | Sale | 213 | $337.05 | $71791.76 |
| 2026-05-26 | HENRY, DAVID PHILIP | EVP, Global Str Mktg & GM, MSD | Sale | 2,500 | $330.50 | $826250.00 |
| 2026-05-22 | MAYAMPURATH, RAMAKUMAR | EVP & CFO | Sale | 8,810 | $315.48 | $2.78M |
| 2026-05-22 | LEE, JOHN TSENG-CHUNG | Director, President & CEO | Sale | 10,000 | $315.48 | $3.15M |
| 2026-05-18 | CANNONE, PETER III | Director | Sale | 1,350 | $303.40 | $409590.14 |
| 2026-05-14 | MOLONEY, JACQUELINE F | Director | Sale | 1,000 | $312.20 | $312196.90 |
| 2026-05-13 | MOLONEY, JACQUELINE F | Director | Sale | 1,400 | $318.99 | $446586.00 |
| 2026-05-11 | TARANTO, ERIC ROBERT | EVP & GM, VSD | Sale | 2,849 | $319.93 | $911480.57 |
| 2026-05-11 | MORA, ELIZABETH | Director | Buy | 782 | — | — |
| 2026-05-11 | MOLONEY, JACQUELINE F | Director | Buy | 782 | — | — |
| 2026-05-11 | JABRE, WISSAM G | Director | Buy | 782 | — | — |
| 2026-05-11 | DONAHUE, JOSEPH B | Director | Buy | 782 | — | — |
| 2026-05-11 | COLELLA, GERALD G | Director | Buy | 782 | — | — |
| 2026-05-11 | CANNONE, PETER III | Director | Buy | 782 | — | — |
| 2026-05-11 | BURKE, KATHLEEN FLAHERTY | EVP, GC & Secretary | Sale | 4,355 | $319.94 | $1.39M |
| 2026-05-11 | BATRA, RAJ | Director | Buy | 782 | — | — |
| 2026-04-17 | WILLIAMS, JOHN EDWARD | EVP & GM, PSD | Sale | 1,741 | — | — |
| 2026-04-17 | WILLIAMS, JOHN EDWARD | EVP & GM, PSD | Buy | 1,741 | — | — |
| 2026-04-17 | WILLIAMS, JOHN EDWARD | EVP & GM, PSD | Sale | 826 | $269.89 | $222929.14 |
| 2026-04-15 | MCCARTHY, MICHELLE M | SVP & Chief Accounting Officer | Sale | 1,736 | — | — |
| 2026-04-15 | MCCARTHY, MICHELLE M | SVP & Chief Accounting Officer | Buy | 1,673 | — | — |
| 2026-04-15 | MCCARTHY, MICHELLE M | SVP & Chief Accounting Officer | Sale | 1,107 | — | — |
| 2026-04-15 | MCCARTHY, MICHELLE M | SVP & Chief Accounting Officer | Sale | 968 | — | — |
| 2026-04-15 | MCCARTHY, MICHELLE M | SVP & Chief Accounting Officer | Buy | 1,736 | — | — |
| 2026-04-15 | MCCARTHY, MICHELLE M | SVP & Chief Accounting Officer | Sale | 1,375 | $274.15 | $376956.25 |
| 2026-04-15 | MCCARTHY, MICHELLE M | SVP & Chief Accounting Officer | Buy | 1,107 | — | — |
| 2026-04-15 | MCCARTHY, MICHELLE M | SVP & Chief Accounting Officer | Buy | 968 | — | — |
| 2026-03-12 | MOLONEY, JACQUELINE F | Director | Sale | 340 | $213.77 | $72682.38 |
| 2026-03-06 | TARANTO, ERIC ROBERT | EVP & GM, VSD | Sale | 4,568 | $220.52 | $1.01M |
| 2026-03-02 | MORA, ELIZABETH | Director | Sale | 300 | $239.44 | $71832.00 |
| 2026-02-24 | SCHREINER, JAMES ALAN | EVP & COO | Sale | 4,100 | $255.00 | $1.05M |
| 2026-02-24 | COLELLA, GERALD G | Director | Sale | 10,000 | $253.97 | $2.54M |
| 2026-02-20 | WILLIAMS, JOHN EDWARD | EVP & GM, PSD | Sale | 2,043 | $256.41 | $523840.52 |
| 2026-02-20 | TARANTO, ERIC ROBERT | EVP & GM, VSD | Sale | 1,453 | $247.55 | $359690.15 |
| 2026-02-20 | MOLONEY, JACQUELINE F | Director | Sale | 829 | $247.55 | $205218.95 |
| 2026-02-20 | MCCARTHY, MICHELLE M | VP & Chief Accounting Officer | Sale | 816 | $250.35 | $204283.89 |
| 2026-02-20 | MCCARTHY, MICHELLE M | VP & Chief Accounting Officer | Sale | 650 | $249.57 | $162218.81 |
| 2026-02-20 | LEE, JOHN TSENG-CHUNG | Director, President & CEO | Sale | 13,310 | $256.05 | $3.41M |
| 2026-02-20 | LEE, JOHN TSENG-CHUNG | Director, President & CEO | Sale | 12,812 | $256.93 | $3.29M |
| 2026-02-20 | LEE, JOHN TSENG-CHUNG | Director, President & CEO | Sale | 1,988 | $257.81 | $512523.10 |
| 2026-02-20 | LEE, JOHN TSENG-CHUNG | Director, President & CEO | Sale | 1,890 | $259.70 | $490839.05 |
| 2026-02-20 | HENRY, DAVID PHILIP | EVP, Global Str Mktg & GM, MSD | Sale | 2,000 | $261.56 | $523120.20 |
| 2026-02-20 | COLELLA, GERALD G | Director | Sale | 10,000 | $252.90 | $2.53M |
| 2026-02-20 | CANNONE, PETER III | Director | Sale | 1,250 | $258.06 | $322574.50 |
| 2026-02-20 | BURKE, KATHLEEN FLAHERTY | EVP, GC & Secretary | Sale | 4,254 | $250.00 | $1.06M |
| 2026-02-17 | WILLIAMS, JOHN EDWARD | EVP & GM, PSD | Buy | 1,474 | — | — |
| 2026-02-17 | WILLIAMS, JOHN EDWARD | EVP & GM, PSD | Sale | 1,106 | — | — |
| 2026-02-17 | WILLIAMS, JOHN EDWARD | EVP & GM, PSD | Sale | 991 | — | — |
| 2026-02-17 | WILLIAMS, JOHN EDWARD | EVP & GM, PSD | Sale | 841 | — | — |
| 2026-02-17 | WILLIAMS, JOHN EDWARD | EVP & GM, PSD | Sale | 300 | — | — |
| 2026-02-17 | WILLIAMS, JOHN EDWARD | EVP & GM, PSD | Sale | 1,195 | $260.74 | $311584.30 |
| 2026-02-17 | WILLIAMS, JOHN EDWARD | EVP & GM, PSD | Buy | 1,106 | — | — |
| 2026-02-17 | WILLIAMS, JOHN EDWARD | EVP & GM, PSD | Buy | 991 | — | — |
| 2026-02-17 | WILLIAMS, JOHN EDWARD | EVP & GM, PSD | Buy | 841 | — | — |
| 2026-02-17 | WILLIAMS, JOHN EDWARD | EVP & GM, PSD | Buy | 300 | — | — |
| 2026-02-17 | TARANTO, ERIC ROBERT | EVP & GM, VSD | Sale | 1,764 | — | — |
| 2026-02-17 | TARANTO, ERIC ROBERT | EVP & GM, VSD | Buy | 1,759 | — | — |
| 2026-02-17 | TARANTO, ERIC ROBERT | EVP & GM, VSD | Sale | 1,303 | — | — |
| 2026-02-17 | TARANTO, ERIC ROBERT | EVP & GM, VSD | Sale | 1,167 | — | — |
| 2026-02-17 | TARANTO, ERIC ROBERT | EVP & GM, VSD | Sale | 976 | — | — |
| 2026-02-17 | TARANTO, ERIC ROBERT | EVP & GM, VSD | Sale | 914 | — | — |
| 2026-02-17 | TARANTO, ERIC ROBERT | EVP & GM, VSD | Sale | 348 | — | — |
| 2026-02-17 | TARANTO, ERIC ROBERT | EVP & GM, VSD | Sale | 2,712 | $260.74 | $707126.88 |
| 2026-02-17 | TARANTO, ERIC ROBERT | EVP & GM, VSD | Buy | 1,764 | — | — |
| 2026-02-17 | TARANTO, ERIC ROBERT | EVP & GM, VSD | Buy | 1,303 | — | — |
| 2026-02-17 | TARANTO, ERIC ROBERT | EVP & GM, VSD | Buy | 1,167 | — | — |
| 2026-02-17 | TARANTO, ERIC ROBERT | EVP & GM, VSD | Buy | 976 | — | — |
| 2026-02-17 | TARANTO, ERIC ROBERT | EVP & GM, VSD | Buy | 914 | — | — |
| 2026-02-17 | TARANTO, ERIC ROBERT | EVP & GM, VSD | Buy | 348 | — | — |
| 2026-02-17 | SCHREINER, JAMES ALAN | EVP & COO | Sale | 2,567 | — | — |
| 2026-02-17 | SCHREINER, JAMES ALAN | EVP & COO | Buy | 2,377 | — | — |
| 2026-02-17 | SCHREINER, JAMES ALAN | EVP & COO | Sale | 1,944 | — | — |
| 2026-02-17 | SCHREINER, JAMES ALAN | EVP & COO | Sale | 1,741 | — | — |
| 2026-02-17 | SCHREINER, JAMES ALAN | EVP & COO | Sale | 1,330 | — | — |
| 2026-02-17 | SCHREINER, JAMES ALAN | EVP & COO | Sale | 1,211 | — | — |
| 2026-02-17 | SCHREINER, JAMES ALAN | EVP & COO | Sale | 432 | — | — |
| 2026-02-17 | SCHREINER, JAMES ALAN | EVP & COO | Sale | 4,344 | $260.74 | $1.13M |
| 2026-02-17 | SCHREINER, JAMES ALAN | EVP & COO | Buy | 2,567 | — | — |
| 2026-02-17 | SCHREINER, JAMES ALAN | EVP & COO | Buy | 1,944 | — | — |
| 2026-02-17 | SCHREINER, JAMES ALAN | EVP & COO | Buy | 1,741 | — | — |
| 2026-02-17 | SCHREINER, JAMES ALAN | EVP & COO | Buy | 1,330 | — | — |
| 2026-02-17 | SCHREINER, JAMES ALAN | EVP & COO | Buy | 1,211 | — | — |
Frequently asked questions
Are MKSI insiders buying or selling?
Over the transactions on record, MKSI insiders have been net sellers, with about $46.11M in stock sold across 69 sales. The entries tagged as buys are stock grants and option exercises recorded at $0, not open-market purchases.
Does insider selling at MKSI mean the stock will fall?
Not by itself. Most executive selling is pre-scheduled through 10b5-1 plans filed months in advance, and insiders sell for diversification, taxes, and liquidity far more often than out of any view on the price. Insider buying is the stronger signal, especially when several insiders buy around the same time, because there is usually only one reason to put personal cash into the stock.
Which MKSI insiders are selling the most?
Recent selling is concentrated in a few names. LEE, JOHN TSENG-CHUNG accounts for the largest share on record, with about $13.88M sold. Selling by one or two individuals matters less than broad selling across the whole leadership team, which is the pattern worth watching.