John Tseng-Chung Lee is COO & VP at MKS INSTRUMENTS INC (MKSI). They have made 20 open-market trades across 1 company since 2009, most recently 2026-08-14.
CIK 0001414656
Unrated. We grade insiders only on stock they chose to buy on the open market. Grants, option exercises and vesting say nothing about timing, so they don't count — which is why someone can file often and still have no grade. It isn't a bad sign: unrated buys beat every graded tier below A.
3 open-market purchases totalling $31K since 2012, against 17 sales. Too few scored purchases to measure a record yet.
| Ticker | Shares | Value |
|---|---|---|
| MKSI | 134,776 | $28.9M |
| CGNX | 24,820 | $1.3M |
| Total | $30.3M |
Shares reported on the most recent Form 4, priced at the 2026-08-17 close.
Counted per filing, not per execution lot — a purchase filled in several tranches is one decision.
| Ticker | Type | Traded | Filed | Price | Value | 7d Stock | 30d Stock | 90d Stock |
|---|---|---|---|---|---|---|---|---|
| MKSI | SELL · 10b5-1 | 2026-08-14 | 2026-08-17 | $302.01 | $3.0M | -10.9% | -22.6% | — |
| MKSI | SELL · 10b5-1 | 2026-05-22 | 2026-05-26 | $315.48 | $3.2M | -10.4% | +22.0% | -20.1% |
| MKSI | SELL | 2026-02-20 | 2026-02-23 | $256.77 | $7.7M | -9.6% | -4.4% | +31.0% |
| MKSI | SELL | 2018-02-20 | 2018-02-21 | $115.35 | $2.9M | +1.1% | +2.3% | -1.3% |
| MKSI | SELL | 2017-11-13 | 2017-11-14 | $104.02 | $440K | +0.7% | -8.0% | +0.7% |
| MKSI | SELL | 2017-02-22 | 2017-02-23 | $67.99 | $2.0M | -2.1% | +2.2% | +19.6% |
| MKSI | SELL | 2016-08-10 | 2016-08-11 | $46.36 | $923K | +4.5% | +0.7% | +7.9% |
| MKSI | SELL · 10b5-1 | 2016-02-26 | 2016-02-29 | $32.70 | $33K | +2.9% | +12.7% | +23.7% |
| MKSI | SELL · 10b5-1 | 2016-02-17 | 2016-02-18 | $33.26 | $46K | +1.9% | +8.3% | +10.0% |
| MKSI | SELL · 10b5-1 | 2016-02-11 | 2016-02-12 | $31.96 | $46K | +0.2% | +6.5% | +11.6% |
| MKSI | SELL | 2015-05-14 | 2015-05-15 | $36.36 | $391K | -6.6% | -1.0% | -1.0% |
| MKSI | SELL | 2014-06-13 | 2014-06-16 | $29.55 | $270K | -6.6% | -1.0% | -1.0% |
| MKSI | BUY | 2013-11-29 | 2013-12-04 | $23.98 | $11K | -6.6% | -1.0% | -1.0% |
| MKSI | BUY | 2013-05-31 | 2013-06-04 | $20.44 | $11K | -6.6% | -1.0% | -1.0% |
| MKSI | SELL | 2013-03-14 | 2013-03-15 | $27.64 | $226K | -6.6% | -1.0% | -1.0% |
| MKSI | BUY | 2012-11-30 | 2012-12-05 | $20.62 | $10K | -6.6% | -1.0% | -1.0% |
| MKSI | SELL | 2012-08-06 | 2012-08-07 | $26.67 | $76K | -6.6% | -1.0% | -1.0% |
| MKSI | SELL | 2012-03-09 | 2012-03-12 | $29.13 | $250K | -6.6% | -1.0% | -1.0% |
| MKSI | SELL | 2011-11-08 | 2011-11-14 | $27.56 | $87K | -6.6% | -1.0% | -1.0% |
| MKSI | SELL · 10b5-1 | 2011-03-17 | 2011-03-18 | $29.31 | $130K | -6.6% | -1.0% | -1.0% |
| MKSI | SELL | 2011-03-08 | 2011-03-09 | $31.82 | $195K | -6.6% | -1.0% | -1.0% |
| MKSI | SELL | 2010-11-05 | 2010-11-09 | $21.60 | $51K | -6.6% | -1.0% | -1.0% |
| MKSI | SELL | 2010-04-26 | 2010-04-27 | $24.15 | $160K | -6.6% | -1.0% | -1.0% |
| MKSI | SELL | 2010-02-11 | 2010-02-16 | $18.74 | $45K | -6.6% | -1.0% | -1.0% |
| MKSI | SELL | 2009-07-28 | 2009-07-30 | $19.13 | $118K | -6.6% | -1.0% | -1.0% |
Grouped by shared companies and similar filing behaviour. This is a similarity measure, not a ranking or a performance signal.