Lee John Tseng-Chung, President and CEO of MKS Instruments ($MKSI), sold shares on the open market four times in the last year, totaling about $7.7 million. His most recent sale occurred on February 20, 2026. These sales rank 1,388th among 11,678 individual insiders in our database, where the average is $8.6 million across roughly 6.4 transactions per insider. He made no open market purchases during this period.
| Transaction Date | Company | Ticker | Insider Name | Title | Transaction Type | Security | Shares | Price | Shares Owned Following | Total Shares Outstanding | % of Owned | % of Outstanding |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Feb. 21, 2026 | COGNEX CORP | $CGNX | Lee John Tseng-Chung | Director | M | Common Stock | 2913 | $0.00 | 24,820.0000 | 169,367,000 | 13.30% | 0.00% |
| Feb. 21, 2026 | COGNEX CORP | $CGNX | Lee John Tseng-Chung | Director | M | Restricted Stock Unit | 2913 | $0.00 | 4,817.0000 | 169,367,000 | 37.68% | 0.00% |
| Feb. 20, 2026 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | S | Common Stock | 13310 | $256.05 | 171,386.1077 | 67,600,000 | 7.21% | 0.02% |
| Feb. 20, 2026 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | S | Common Stock | 12812 | $256.93 | 158,574.1077 | 67,600,000 | 7.48% | 0.02% |
| Feb. 20, 2026 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | S | Common Stock | 1988 | $257.81 | 156,586.1077 | 67,600,000 | 1.25% | 0.00% |
| Feb. 20, 2026 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | S | Common Stock | 1890 | $259.70 | 154,696.1077 | 67,600,000 | 1.21% | 0.00% |
| Feb. 18, 2026 | COGNEX CORP | $CGNX | Lee John Tseng-Chung | Director | M | Common Stock | 8324 | $0.00 | 21,907.0000 | 169,367,000 | 61.28% | 0.00% |
| Feb. 17, 2026 | COGNEX CORP | $CGNX | Lee John Tseng-Chung | Director | A | Restricted Stock Unit | 4817 | $0.00 | 7,730.0000 | 169,367,000 | 165.36% | 0.00% |
| Feb. 18, 2026 | COGNEX CORP | $CGNX | Lee John Tseng-Chung | Director | M | Restricted Stock Unit | 8324 | $0.00 | 2,913.0000 | 169,367,000 | 74.08% | 0.00% |
| Feb. 17, 2026 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 22088 | $0.00 | 132,629.2820 | 67,600,000 | 14.28% | 0.03% |
| Feb. 17, 2026 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | F | Common Stock | 32548 | $260.74 | 184,696.1077 | 67,600,000 | 14.98% | 0.05% |
| Feb. 17, 2026 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 12091 | $0.00 | 217,244.4147 | 67,600,000 | 5.89% | 0.02% |
| Feb. 17, 2026 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 16989 | $0.00 | 205,153.4147 | 67,600,000 | 9.03% | 0.03% |
| Feb. 17, 2026 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 7208 | $0.00 | 188,163.9747 | 67,600,000 | 3.98% | 0.01% |
| Feb. 17, 2026 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 3859 | $0.00 | 180,955.9747 | 67,600,000 | 2.18% | 0.01% |
| Feb. 17, 2026 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 7654 | $0.00 | 177,096.8547 | 67,600,000 | 4.52% | 0.01% |
| Feb. 17, 2026 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 22088 | $0.00 | 169,443.2537 | 67,600,000 | 14.99% | 0.03% |
| Feb. 17, 2026 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 12091 | $0.00 | 84,828.1210 | 67,600,000 | 12.48% | 0.02% |
| Feb. 17, 2026 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 16989 | $0.00 | 96,919.1210 | 67,600,000 | 14.91% | 0.03% |
| Feb. 17, 2026 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 7208 | $0.00 | 113,908.5610 | 67,600,000 | 5.95% | 0.01% |
| Feb. 17, 2026 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 3859 | $0.00 | 121,116.5610 | 67,600,000 | 3.09% | 0.01% |
| Feb. 17, 2026 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 7654 | $0.00 | 124,975.6810 | 67,600,000 | 5.77% | 0.01% |
| Feb. 17, 2026 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | A | Restricted Stock Unit | 15593 | $0.00 | 154,717.3730 | 67,600,000 | 11.21% | 0.02% |
| Feb. 8, 2026 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | A | Restricted Stock Unit | 50972 | $0.00 | 139,124.4620 | 67,600,000 | 57.82% | 0.08% |
| Oct. 31, 2025 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 1651 | $0.00 | 149,272.5227 | 67,600,000 | 1.12% | 0.00% |
| Oct. 31, 2025 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 352 | $0.00 | 147,621.5227 | 67,600,000 | 0.24% | 0.00% |
| Oct. 31, 2025 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 352 | $0.00 | 89,803.6220 | 67,600,000 | 0.39% | 0.00% |
| Oct. 31, 2025 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 1651 | $0.00 | 88,152.6220 | 67,600,000 | 1.84% | 0.00% |
| Oct. 31, 2025 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | F | Common Stock | 2003 | $143.71 | 147,269.5227 | 67,600,000 | 1.34% | 0.00% |
| May 9, 2025 | COGNEX CORP | $CGNX | Lee John Tseng-Chung | Director | M | Restricted Stock Unit | 1848 | $0.00 | 11,237.0000 | 172,611,000 | 14.12% | 0.00% |
| May 9, 2025 | COGNEX CORP | $CGNX | Lee John Tseng-Chung | Director | M | Common Stock | 1848 | $0.00 | 13,583.0000 | 172,611,000 | 15.75% | 0.00% |
| Feb. 20, 2025 | COGNEX CORP | $CGNX | Lee John Tseng-Chung | Director | M | Restricted Stock Unit | 6973 | $0.00 | 10,172.0000 | 172,611,000 | 40.67% | 0.00% |
| Feb. 21, 2025 | COGNEX CORP | $CGNX | Lee John Tseng-Chung | Director | M | Common Stock | 1747 | $0.00 | 11,735.0000 | 172,611,000 | 17.49% | 0.00% |
| Feb. 20, 2025 | COGNEX CORP | $CGNX | Lee John Tseng-Chung | Director | M | Common Stock | 6973 | $0.00 | 9,988.0000 | 172,611,000 | 231.28% | 0.00% |
| Feb. 21, 2025 | COGNEX CORP | $CGNX | Lee John Tseng-Chung | Director | M | Restricted Stock Unit | 1747 | $0.00 | 13,085.0000 | 172,611,000 | 11.78% | 0.00% |
| Feb. 18, 2025 | COGNEX CORP | $CGNX | Lee John Tseng-Chung | Director | A | Restricted Stock Unit | 8324 | $0.00 | 21,805.0000 | 172,611,000 | 61.75% | 0.00% |
| Feb. 18, 2025 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 4035 | $0.00 | 97,362.6220 | 67,600,000 | 3.98% | 0.01% |
| Feb. 18, 2025 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 14041 | $0.00 | 126,729.9897 | 67,600,000 | 12.46% | 0.02% |
| Feb. 18, 2025 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 6735 | $0.00 | 133,465.3157 | 67,600,000 | 5.31% | 0.01% |
| Feb. 18, 2025 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 22088 | $0.00 | 155,553.3157 | 67,600,000 | 16.55% | 0.03% |
| Feb. 18, 2025 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 7654 | $0.00 | 163,207.3157 | 67,600,000 | 4.92% | 0.01% |
| Feb. 18, 2025 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 4035 | $0.00 | 167,242.4357 | 67,600,000 | 2.47% | 0.01% |
| Feb. 18, 2025 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 7207 | $0.00 | 174,449.4357 | 67,600,000 | 4.31% | 0.01% |
| Feb. 18, 2025 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | F | Common Stock | 27332 | $103.67 | 147,117.4357 | 67,600,000 | 15.67% | 0.04% |
| Feb. 18, 2025 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | A | Restricted Stock Unit | 37925 | $0.00 | 151,916.5080 | 67,600,000 | 33.27% | 0.06% |
| Feb. 18, 2025 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 14041 | $0.00 | 137,875.0680 | 67,600,000 | 9.24% | 0.02% |
| Feb. 18, 2025 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 6735 | $0.00 | 131,139.7420 | 67,600,000 | 4.89% | 0.01% |
| Feb. 18, 2025 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 22088 | $0.00 | 109,051.7420 | 67,600,000 | 16.84% | 0.03% |
| Feb. 18, 2025 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 7654 | $0.00 | 101,397.7420 | 67,600,000 | 7.02% | 0.01% |
| Feb. 18, 2025 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 7207 | $0.00 | 90,155.6220 | 67,600,000 | 7.40% | 0.01% |
| Feb. 10, 2025 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | A | Restricted Stock Unit | 12107 | $0.00 | 113,991.0320 | 67,600,000 | 11.88% | 0.02% |
| Dec. 6, 2024 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 984 | $0.00 | 101,884.4520 | 67,600,000 | 0.96% | 0.00% |
| Dec. 6, 2024 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 2010 | $0.00 | 114,698.5497 | 67,600,000 | 1.78% | 0.00% |
| Dec. 6, 2024 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 984 | $0.00 | 115,682.5497 | 67,600,000 | 0.86% | 0.00% |
| Dec. 6, 2024 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | F | Common Stock | 2994 | $114.60 | 112,688.5497 | 67,600,000 | 2.59% | 0.00% |
| Dec. 6, 2024 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 2010 | $0.00 | 102,868.4520 | 67,600,000 | 1.92% | 0.00% |
| May 9, 2024 | COGNEX CORP | $CGNX | Lee John Tseng-Chung | Director | M | Common Stock | 1109 | $0.00 | 3,015.0000 | 173,399,000 | 58.18% | 0.00% |
| May 9, 2024 | COGNEX CORP | $CGNX | Lee John Tseng-Chung | Director | M | Restricted Stock Unit | 1109 | $0.00 | 13,481.0000 | 173,399,000 | 7.60% | 0.00% |
| Feb. 21, 2024 | COGNEX CORP | $CGNX | Lee John Tseng-Chung | Director | M | Common Stock | 1166 | $0.00 | 1,906.0000 | 173,399,000 | 157.57% | 0.00% |
| Feb. 20, 2024 | COGNEX CORP | $CGNX | Lee John Tseng-Chung | Director | A | Restricted Stock Unit | 6973 | $0.00 | 9,930.0000 | 173,399,000 | 235.81% | 0.00% |
| Feb. 21, 2024 | COGNEX CORP | $CGNX | Lee John Tseng-Chung | Director | M | Restricted Stock Unit | 1166 | $0.00 | 7,617.0000 | 173,399,000 | 13.28% | 0.00% |
| Feb. 15, 2024 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 7653 | $0.00 | 104,878.4520 | 66,800,000 | 6.80% | 0.01% |
| Feb. 15, 2024 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 3778 | $0.00 | 91,151.0107 | 66,800,000 | 4.32% | 0.01% |
| Feb. 15, 2024 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 6734 | $0.00 | 111,926.0107 | 66,800,000 | 6.40% | 0.01% |
| Feb. 15, 2024 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 23093 | $0.00 | 112,531.4520 | 66,800,000 | 17.03% | 0.03% |
| Feb. 15, 2024 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 6734 | $0.00 | 135,624.4520 | 66,800,000 | 4.73% | 0.01% |
| Feb. 15, 2024 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 14041 | $0.00 | 142,358.4520 | 66,800,000 | 8.98% | 0.02% |
| Feb. 15, 2024 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 3778 | $0.00 | 156,399.4520 | 66,800,000 | 2.36% | 0.01% |
| Feb. 15, 2024 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 9235 | $0.00 | 160,177.2990 | 66,800,000 | 5.45% | 0.01% |
| Feb. 15, 2024 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | A | Restricted Stock Unit | 22608 | $0.00 | 169,412.7020 | 66,800,000 | 15.40% | 0.03% |
| Feb. 15, 2024 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | F | Common Stock | 30231 | $122.15 | 112,441.0107 | 66,800,000 | 21.19% | 0.05% |
| Feb. 15, 2024 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 7653 | $0.00 | 142,672.0107 | 66,800,000 | 5.67% | 0.01% |
| Feb. 15, 2024 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 23093 | $0.00 | 135,019.0107 | 66,800,000 | 20.63% | 0.03% |
| Feb. 15, 2024 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 14041 | $0.00 | 105,192.0107 | 66,800,000 | 15.40% | 0.02% |
| Feb. 15, 2024 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 9235 | $0.00 | 87,373.1637 | 66,800,000 | 11.82% | 0.01% |
| Feb. 5, 2024 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | A | Restricted Stock Unit | 69279 | $0.00 | 146,804.7080 | 66,800,000 | 89.36% | 0.10% |
| Dec. 1, 2023 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 970 | $0.00 | 77,525.1180 | 59,900,000 | 1.24% | 0.00% |
| Dec. 1, 2023 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 390 | $0.00 | 78,528.6070 | 59,900,000 | 0.50% | 0.00% |
| Dec. 1, 2023 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 1186 | $0.00 | 79,714.6070 | 59,900,000 | 1.51% | 0.00% |
| Dec. 1, 2023 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 160 | $0.00 | 79,874.6070 | 59,900,000 | 0.20% | 0.00% |
| Dec. 1, 2023 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 569 | $0.00 | 80,443.6070 | 59,900,000 | 0.71% | 0.00% |
| Dec. 1, 2023 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 970 | $0.00 | 81,413.6070 | 59,900,000 | 1.21% | 0.00% |
| Dec. 1, 2023 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | F | Common Stock | 3275 | $84.19 | 78,138.6070 | 59,900,000 | 4.02% | 0.01% |
| Dec. 1, 2023 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 390 | $0.00 | 80,410.1180 | 59,900,000 | 0.48% | 0.00% |
| Dec. 1, 2023 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 1186 | $0.00 | 79,224.1180 | 59,900,000 | 1.47% | 0.00% |
| Dec. 1, 2023 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 160 | $0.00 | 79,064.1180 | 59,900,000 | 0.20% | 0.00% |
| Dec. 1, 2023 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 569 | $0.00 | 78,495.1180 | 59,900,000 | 0.72% | 0.00% |
| Feb. 15, 2023 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 7536 | $0.00 | 59,229.8450 | 59,900,000 | 14.58% | 0.01% |
| Feb. 15, 2023 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 7018 | $0.00 | 80,800.1180 | 59,900,000 | 7.99% | 0.01% |
| Feb. 15, 2023 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 14634 | $0.00 | 87,818.1180 | 59,900,000 | 14.28% | 0.02% |
| Feb. 15, 2023 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 3937 | $0.00 | 102,452.1180 | 59,900,000 | 3.70% | 0.01% |
| Feb. 15, 2023 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 9624 | $0.00 | 106,389.1180 | 59,900,000 | 8.30% | 0.02% |
| Feb. 15, 2023 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 4282 | $0.00 | 116,013.1180 | 59,900,000 | 3.56% | 0.01% |
| Feb. 15, 2023 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Restricted Stock Unit | 7536 | $0.00 | 120,294.7120 | 59,900,000 | 5.90% | 0.01% |
| Feb. 15, 2023 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | A | Restricted Stock Unit | 23931 | $0.00 | 127,830.4360 | 59,900,000 | 23.03% | 0.04% |
| Feb. 15, 2023 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | F | Common Stock | 20862 | $100.29 | 77,862.4390 | 59,900,000 | 21.13% | 0.03% |
| Feb. 15, 2023 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 7018 | $0.00 | 98,724.4390 | 59,900,000 | 7.65% | 0.01% |
| Feb. 15, 2023 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 14634 | $0.00 | 91,706.4390 | 59,900,000 | 18.99% | 0.02% |
| Feb. 15, 2023 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 3937 | $0.00 | 77,072.4390 | 59,900,000 | 5.38% | 0.01% |
| Feb. 15, 2023 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 9624 | $0.00 | 73,135.4390 | 59,900,000 | 15.15% | 0.02% |
| Feb. 15, 2023 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | M | Common Stock | 4282 | $0.00 | 63,511.4390 | 59,900,000 | 7.23% | 0.01% |
| Feb. 8, 2023 | MKS INC | $MKSI | Lee John Tseng-Chung | President & CEO | A | Restricted Stock Unit | 43902 | $0.00 | 103,899.8350 | 59,900,000 | 73.17% | 0.07% |