MKS (MKSI) stock: insider trades, news & valuation
Heavy selling
Close · Oct 9, 2026
$264.50
+1.6% on the day
+97.8% over 12 months
52-week range $120.75 – $444.39
Share price and insider trades
MKSI closeInsider buyInsider sale
Bought, 12 months$0
Sold, 12 months$43.5M
Insiders buying0
Insiders selling13
MKS insider trading at a glance (Oct 9, 2026): in the past 12 months, 0 insiders bought $0 and 13 sold $43.5M of MKSI stock on the open market.
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MKSI insider buying and selling by quarter
Open-market purchases (green, above the line) and sales (red, below), by trade date.
| Quarter | Bought | Purchases | Sold | Sales |
|---|---|---|---|---|
| Q4 2026 | — | 0 | — | 0 |
| Q3 2026 | — | 0 | $3.2M | 3 |
| Q2 2026 | — | 0 | $21.8M | 23 |
| Q1 2026 | — | 0 | $18.3M | 18 |
| Q4 2025 | — | 0 | $183K | 3 |
Valuation, profit and volume
P/E (trailing)n/aSector median —
Market value—
Profit margin—Revenue growth —
Volume vs. 50-day0.7×Last 5 sessions
Insiders' paper profit—On all tracked purchases —
Summary
Over the past 12 months, 0 MKS INC insiders reported open-market purchases totaling $0, while 13 insiders reported sales totaling $43.5M. 20 of 47 recorded sales were made under pre-scheduled Rule 10b5-1 trading plans, which are usually less informative than discretionary sales.
Insider transactions
Open-market purchases and sales.
| Filed | Insider | Type | Shares | Price | Value | Since | Score |
|---|---|---|---|---|---|---|---|
| Sep 2SEC | Elizabeth MoraDirector | Sell Plan | 30018,845 held (−2%) | $250.96 | $75K | +5.4% | — |
| Aug 17SEC | John Tseng-chung LeeCEO, President | Sell Plan | 10,000134,776 held (−7%) | $302.01 | $3.0M | -12.4% | — |
| Aug 4SEC | John Edward WilliamsEvp & Gm, Psd | Sell Plan | 4574,098 held (−10%) | $288.31 | $132K | -8.3% | — |
| Jun 16SEC | James Alan SchreinerCOO | Sell | 2,47120,230 held (−11%) | $345.52 | $854K | -23.4% | — |
| Jun 16SEC | James Alan SchreinerCOO | Sell | 81219,418 held (−4%) | $346.41 | $281K | -23.6% | — |
| Jun 16SEC | James Alan SchreinerCOO | Sell | 21719,201 held (−1%) | $347.00 | $75K | -23.8% | — |
| Jun 11SEC | James Alan SchreinerCOO | Sell Plan | 78122,701 held (−3%) | $317.42 | $248K | -16.7% | — |
| Jun 8SEC | Michelle M MccarthySvp & Chief Accounting Officer | Sell Plan | 2,4342 held (−100%) | $315.23 | $767K | -16.1% | — |
| Jun 2SEC | David Philip HenryEvp, Global Str Mktg & Gm, Msd | Sell | 6,00010,422 held (−37%) | $314.43 | $1.9M | -15.9% | — |
| Jun 2SEC | Elizabeth MoraDirector | Sell Plan | 30019,145 held (−2%) | $318.02 | $95K | -16.8% | — |
| May 28SEC | Gerald G ColellaDirector | Sell Plan | 8,21031,343 held (−21%) | $331.45 | $2.7M | -20.2% | — |
| May 28SEC | Gerald G ColellaDirector | Sell Plan | 4,87626,467 held (−16%) | $332.04 | $1.6M | -20.3% | — |
| May 28SEC | Gerald G ColellaDirector | Sell Plan | 2,80020,017 held (−12%) | $338.58 | $948K | -21.9% | — |
| May 28SEC | Joseph B DonahueDirector | Sell | 2,10010,033 held (−17%) | $327.95 | $689K | -19.3% | — |
| May 28SEC | Gerald G ColellaDirector | Sell Plan | 1,81124,656 held (−7%) | $335.46 | $608K | -21.2% | — |
| May 28SEC | Gerald G ColellaDirector | Sell Plan | 1,62623,030 held (−7%) | $336.54 | $547K | -21.4% | — |
| May 28SEC | Gerald G ColellaDirector | Sell Plan | 46439,553 held (−1%) | $330.38 | $153K | -19.9% | — |
| May 28SEC | Gerald G ColellaDirector | Sell Plan | 21322,817 held (−1%) | $337.05 | $72K | -21.5% | — |
| May 27SEC | David Philip HenryEvp, Global Str Mktg & Gm, Msd | Sell Plan | 2,50016,341 held (−13%) | $330.50 | $826K | -20.0% | — |
| May 26SEC | John Tseng-chung LeeCEO, President | Sell Plan | 10,000144,696 held (−6%) | $315.48 | $3.2M | -16.2% | — |
| May 26SEC | Ramakumar MayampurathCFO | Sell Plan | 8,8101 held (−100%) | $315.48 | $2.8M | -16.2% | — |
| May 19SEC | Peter Cannone IIIDirector | Sell | 1,3507,794 held (−15%) | $303.40 | $410K | -12.8% | — |
| May 15SEC | Jacqueline F MoloneyDirector | Sell | 1,0008,775 held (−10%) | $312.20 | $312K | -15.3% | — |
| May 14SEC | Jacqueline F MoloneyDirector | Sell | 1,4009,775 held (−13%) | $318.99 | $447K | -17.1% | — |
| May 12SEC | Kathleen Flaherty BurkeEvp, Gc & Secretary | Sell | 4,35549,439 held (−8%) | $319.94 | $1.4M | -17.3% | — |
| May 12SEC | Eric Robert TarantoEvp & Gm, Vsd | Sell | 2,84912,596 held (−18%) | $319.93 | $911K | -17.3% | — |
| Mar 13SEC | Jacqueline F MoloneyDirector | Sell | 34010,393 held (−3%) | $213.77 | $73K | +23.7% | — |
| Mar 9SEC | Eric Robert TarantoEvp & Gm, Vsd | Sell | 4,56815,445 held (−23%) | $220.52 | $1.0M | +19.9% | — |
| Mar 3SEC | Elizabeth MoraDirector | Sell Plan | 30018,663 held (−2%) | $239.44 | $72K | +10.5% | — |
| Feb 25SEC | James Alan SchreinerCOO | Sell | 4,10023,402 held (−15%) | $255.00 | $1.0M | +3.7% | — |
| Feb 24SEC | Gerald G ColellaDirector | Sell | 10,00040,017 held (−20%) | $253.97 | $2.5M | +4.1% | — |
| Feb 24SEC | Gerald G ColellaDirector | Sell | 10,00050,017 held (−17%) | $252.90 | $2.5M | +4.6% | — |
| Feb 23SEC | John Tseng-chung LeeCEO, President | Sell | 13,310171,386 held (−7%) | $256.05 | $3.4M | +3.3% | — |
| Feb 23SEC | John Tseng-chung LeeCEO, President | Sell | 12,812158,574 held (−7%) | $256.93 | $3.3M | +2.9% | — |
| Feb 23SEC | Kathleen Flaherty BurkeEvp, Gc & Secretary | Sell | 4,25453,794 held (−7%) | $250.00 | $1.1M | +5.8% | — |
| Feb 23SEC | John Edward WilliamsEvp & Gm, Psd | Sell | 2,0433,640 held (−36%) | $256.41 | $524K | +3.2% | — |
| Feb 23SEC | David Philip HenryEvp, Global Str Mktg & Gm, Msd | Sell | 2,00018,841 held (−10%) | $261.56 | $523K | +1.1% | — |
| Feb 23SEC | John Tseng-chung LeeCEO, President | Sell | 1,988156,586 held (−1%) | $257.81 | $513K | +2.6% | — |
| Feb 23SEC | John Tseng-chung LeeCEO, President | Sell | 1,890154,696 held (−1%) | $259.70 | $491K | +1.8% | — |
| Feb 23SEC | Eric Robert TarantoEvp & Gm, Vsd | Sell | 1,45320,013 held (−7%) | $247.55 | $360K | +6.8% | — |
| Feb 23SEC | Peter Cannone IIIDirector | Sell | 1,2508,362 held (−13%) | $258.06 | $323K | +2.5% | — |
| Feb 23SEC | Jacqueline F MoloneyDirector | Sell | 82910,733 held (−7%) | $247.55 | $205K | +6.8% | — |
| Feb 23SEC | Michelle M MccarthyVp & Chief Accounting Officer | Sell | 816 | $250.35 | $204K | +5.7% | — |
| Feb 23SEC | Michelle M MccarthyVp & Chief Accounting Officer | Sell | 650816 held (−44%) | $249.57 | $162K | +6.0% | — |
| Dec 3SEC | Elizabeth MoraDirector | Sell Plan | 30018,963 held (−2%) | $158.81 | $48K | +66.6% | — |
| Oct 23SEC | James Alan SchreinerCOO | Sell Plan | 71122,535 held (−3%) | $138.68 | $99K | +90.7% | — |
| Oct 2SEC | Jacqueline F MoloneyDirector | Sell Plan | 30011,562 held (−3%) | $122.14 | $37K | +116.6% | — |
Insiders at MKS INC
| Insider | Bought | Sold | Last filing | Score |
|---|---|---|---|---|
| John Tseng-chung LeeCEO, President | — | $13.9M | Aug 17, 2026 | — |
| Gerald G ColellaDirector | — | $11.7M | May 28, 2026 | — |
| David Philip HenryEvp, Global Str Mktg & Gm, Msd | — | $3.2M | Jun 2, 2026 | — |
| Ramakumar MayampurathCFO | — | $2.8M | May 26, 2026 | — |
| James Alan SchreinerCOO | — | $2.6M | Jun 16, 2026 | — |
| Kathleen Flaherty BurkeEvp, Gc & Secretary | — | $2.5M | May 12, 2026 | — |
| Eric Robert TarantoEvp & Gm, Vsd | — | $2.3M | May 12, 2026 | — |
| Michelle M MccarthySvp & Chief Accounting Officer | — | $1.1M | Jun 8, 2026 | — |
| Jacqueline F MoloneyDirector | — | $1.1M | May 15, 2026 | — |
| Peter Cannone IIIDirector | — | $732K | May 19, 2026 | — |
| Joseph B DonahueDirector | — | $689K | May 28, 2026 | — |
| John Edward WilliamsEvp & Gm, Psd | — | $656K | Aug 4, 2026 | — |
| Elizabeth MoraDirector | — | $290K | Sep 2, 2026 | — |
MKSI stock: common questions
Are MKS INC insiders buying MKSI stock?
In the past 12 months, 0 insiders reported open-market purchases of MKSI worth $0.
Are MKS INC insiders selling MKSI stock?
13 insiders reported sales worth $43.5M over the same period.
Where does this data come from?
Every transaction comes from Form 4 filings that insiders must submit to the SEC within two business days of a trade. We pull them from SEC EDGAR every night.
What is MKSI's 52-week range?
Over the past year MKSI has traded between $120.75 and $444.39. It last closed at $264.50 on Oct 9, 2026.