John Tseng Chung Lee Mks Instruments Inc (MKSI) insider trading activity

John Tseng Chung Lee is President & CEO of MKS INSTRUMENTS INC. Currently has a direct ownership of 147,269 shares of MKSI, which is worth approximately $21 Million. The most recent transaction as insider was on Oct 31, 2025, when has been sold 2,003 shares (Common Stock) at a price of $143.71 per share, resulting in proceeds of $287,851. This information was disclosed in a Form 4 filing with the Securities and Exchange Commission (SEC).

Shares Held (Direct Ownership) 147K

0.1% 3M change

30.97% 12M change

Total Value Held $21 Million

John Tseng-Chung Lee Transaction History

Date	Transaction	Value	Shares Traded	Shares Held
Oct 31 2025	SELL Payment of exercise price or tax liability	$287,851 $143.71 p/Share	2,003 Reduced 1.34%	147,269 Common Stock
Oct 31 2025	BUY Exercise of conversion of derivative security	-	2,003 Added 1.32%	149,272 Common Stock
Feb 18 2025	SELL Payment of exercise price or tax liability	$2,833,508 $103.67 p/Share	27,332 Reduced 15.67%	147,117 Common Stock
Feb 18 2025	BUY Exercise of conversion of derivative security	-	61,760 Added 26.15%	174,449 Common Stock
Dec 06 2024	SELL Payment of exercise price or tax liability	$343,112 $114.6 p/Share	2,994 Reduced 2.59%	112,688 Common Stock
Dec 06 2024	BUY Exercise of conversion of derivative security	-	2,994 Added 2.52%	115,682 Common Stock
Feb 15 2024	SELL Payment of exercise price or tax liability	$3,692,716 $122.15 p/Share	30,231 Reduced 21.19%	112,441 Common Stock

Feb 15 2024	BUY Exercise of conversion of derivative security	-	64,533 Added 31.14%	142,672 Common Stock
Dec 01 2023	SELL Payment of exercise price or tax liability	$275,722 $84.19 p/Share	3,275 Reduced 4.02%	78,138 Common Stock
Dec 01 2023	BUY Exercise of conversion of derivative security	-	3,275 Added 3.87%	81,413 Common Stock
Feb 15 2023	SELL Payment of exercise price or tax liability	$2,092,249 $100.29 p/Share	20,862 Reduced 21.13%	77,862 Common Stock
Feb 15 2023	BUY Exercise of conversion of derivative security	-	47,029 Added 32.27%	98,724 Common Stock
Feb 15 2022	SELL Payment of exercise price or tax liability	$2,111,139 $152.55 p/Share	13,839 Reduced 21.18%	51,516 Common Stock
Feb 15 2022	BUY Exercise of conversion of derivative security	-	31,196 Added 32.31%	65,355 Common Stock
Feb 16 2021	SELL Payment of exercise price or tax liability	$1,688,249 $172.2 p/Share	9,804 Reduced 22.38%	34,001 Common Stock
Feb 16 2021	BUY Exercise of conversion of derivative security	-	22,093 Added 33.53%	43,805 Common Stock

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