Transactions
26
Insider / MKS INC
Lee John Tseng-Chung
President & CEO at MKS INC
- Company
- MKS INC
- Ticker
- MKSI
- First filing on record
- November 4, 2025
- Latest trade on record
- August 14, 2026
- SEC filings
- EDGAR ↗
Lee John Tseng-Chung, President & CEO at MKS INC, has disclosed 26 transactions in MKSI since November 4, 2025: 0 purchases (0 open-market buys) and 8 sales, worth about $22.7M at the reported prices. The latest was filed August 17, 2026, 3 days after the trade.
Open-market buys
0
Sales
8
Avg. disclosure lag
2.1d
Trading in charts
Trade timeline
When does this person trade, how big, and in which direction? Every trade in the last 12 months.
Bought (above the line)Sold (below the line)Other transaction
In the last 12 months Lee John Tseng-Chung made no purchases and 8 sales worth $23M, plus 18 other transactions. Dot size is the dollar amount.
Portfolio mix
Which stocks does this person trade most? Tile size is dollars traded, all time on record.
Lee John Tseng-Chung has traded 1 stock on record; the largest by dollars is MKSI.
Reporting lag
Does this person report on time? One bar per filing against the Form 4 deadline.
On timeLate
0 of 6 filings on record were reported after the Form 4 deadline (two business days, counted here as 4 calendar days).
What kind of transactions
Most Form 4 rows are pay arriving or tax being withheld, not a decision to buy or sell. Only code P is an open-market purchase and code S an open-market sale. What each code means: Form 4 transaction codes.
| Code | Meaning | Rows | Shares | Value |
|---|---|---|---|---|
| M | Option exercise or conversion | 16 | 143,785 | — |
| S | Open-market sale | 6 | 50,000 | $13.9M |
| A | Grant or award | 2 | 66,565 | — |
| F | Shares withheld for tax | 2 | 34,551 | $8.8M |
| Year | Rows | Bought | Sold |
|---|---|---|---|
| 2026 | 21 | 0 | 7 · $22.4M |
| 2025 | 5 | 0 | 1 · $288K |
Transactions
| Security | Side | Trade date | Disclosed | Lag | Shares | Price | Value | Flags | Source | Share |
|---|---|---|---|---|---|---|---|---|---|---|
| MKSI | Sell S | August 14, 2026 | August 17, 2026 | 3d | 10,000 | $302 | $3.0M | 10b5-1 plan | Form 4 ↗ | |
| MKSI | Sell S | May 22, 2026 | May 26, 2026 | 4d | 10,000 | $315 | $3.2M | 10b5-1 plan | Form 4 ↗ | |
| MKSI | Sell S | February 20, 2026 | February 23, 2026 | 3d | 1,890 | $260 | $491K | Form 4 ↗ | ||
| MKSI | Sell S | February 20, 2026 | February 23, 2026 | 3d | 1,988 | $258 | $513K | Form 4 ↗ | ||
| MKSI | Sell S | February 20, 2026 | February 23, 2026 | 3d | 12,812 | $257 | $3.3M | Form 4 ↗ | ||
| MKSI | Sell S | February 20, 2026 | February 23, 2026 | 3d | 13,310 | $256 | $3.4M | Form 4 ↗ | ||
| MKSI | Option / conversion M | February 17, 2026 | February 18, 2026 | 1d | 12,091 | — | — | derivative | Form 4 ↗ | |
| MKSI | Option / conversion M | February 17, 2026 | February 18, 2026 | 1d | 16,989 | — | — | derivative | Form 4 ↗ | |
| MKSI | Option / conversion M | February 17, 2026 | February 18, 2026 | 1d | 7,208 | — | — | derivative | Form 4 ↗ | |
| MKSI | Option / conversion M | February 17, 2026 | February 18, 2026 | 1d | 3,859 | — | — | derivative | Form 4 ↗ | |
| MKSI | Option / conversion M | February 17, 2026 | February 18, 2026 | 1d | 7,654 | — | — | derivative | Form 4 ↗ | |
| MKSI | Option / conversion M | February 17, 2026 | February 18, 2026 | 1d | 22,088 | — | — | derivative | Form 4 ↗ | |
| MKSI | Other A | February 17, 2026 | February 18, 2026 | 1d | 15,593 | — | — | derivative | Form 4 ↗ | |
| MKSI | Sell F | February 17, 2026 | February 18, 2026 | 1d | 32,548 | $261 | $8.5M | Form 4 ↗ | ||
| MKSI | Option / conversion M | February 17, 2026 | February 18, 2026 | 1d | 12,091 | — | — | Form 4 ↗ | ||
| MKSI | Option / conversion M | February 17, 2026 | February 18, 2026 | 1d | 16,989 | — | — | Form 4 ↗ | ||
| MKSI | Option / conversion M | February 17, 2026 | February 18, 2026 | 1d | 7,208 | — | — | Form 4 ↗ | ||
| MKSI | Option / conversion M | February 17, 2026 | February 18, 2026 | 1d | 3,859 | — | — | Form 4 ↗ | ||
| MKSI | Option / conversion M | February 17, 2026 | February 18, 2026 | 1d | 7,654 | — | — | Form 4 ↗ | ||
| MKSI | Option / conversion M | February 17, 2026 | February 18, 2026 | 1d | 22,088 | — | — | Form 4 ↗ | ||
| MKSI | Other A | February 8, 2026 | February 9, 2026 | 1d | 50,972 | — | — | derivative | Form 4 ↗ | |
| MKSI | Option / conversion M | October 31, 2025 | November 4, 2025 | 4d | 1,651 | — | — | derivative | Form 4 ↗ | |
| MKSI | Option / conversion M | October 31, 2025 | November 4, 2025 | 4d | 352 | — | — | derivative | Form 4 ↗ | |
| MKSI | Sell F | October 31, 2025 | November 4, 2025 | 4d | 2,003 | $144 | $288K | Form 4 ↗ | ||
| MKSI | Option / conversion M | October 31, 2025 | November 4, 2025 | 4d | 1,651 | — | — | Form 4 ↗ | ||
| MKSI | Option / conversion M | October 31, 2025 | November 4, 2025 | 4d | 352 | — | — | Form 4 ↗ |
Filings
| Filed | Form | Accession | Rows | Status | Source |
|---|---|---|---|---|---|
| August 17, 2026 | Form 4 | 0001049502-26-000113 | 1 | published | EDGAR ↗ |
| May 26, 2026 | Form 4 | 0001049502-26-000088 | 1 | published | EDGAR ↗ |
| February 23, 2026 | Form 4 | 0001049502-26-000030 | 4 | published | EDGAR ↗ |
| February 18, 2026 | Form 4 | 0001049502-26-000016 | 14 | published | EDGAR ↗ |
| February 9, 2026 | Form 4 | 0001049502-26-000002 | 1 | published | EDGAR ↗ |
| November 4, 2025 | Form 4 | 0001049502-25-000035 | 5 | published | EDGAR ↗ |
Other insiders at MKS INC
- Burke Kathleen Flaherty EVP, GC & Secretary 28 rows
- Schreiner James Alan EVP & COO 21 rows
- Henry David Philip EVP, Global Str Mktg & GM, MSD 18 rows
- Taranto Eric Robert EVP & GM, VSD 18 rows
- Williams John Edward EVP & GM, PSD 16 rows
- Mayampurath Ramakumar EVP & CFO 11 rows
- McCarthy Michelle M SVP & Chief Accounting Officer 11 rows
- COLELLA GERALD G Director 10 rows
- Moloney Jacqueline F Director 6 rows
- Mora Elizabeth Director 5 rows
Everyone on file, with contracts and lobbying under the company's name: MKS INC.
Guides for this page
- What is SEC Form 4? Who files: officers, directors and owners of more than 10% of a class of the company's shares.
- Form 4 transaction codes P = purchase. S = sale. These are the two market trades.
- Insider buying vs insider selling Selling outweighs buying by a wide margin in normal times.
- Rule 10b5-1 trading plans The plan must be set up when the insider has no important non-public information.
- Options and derivatives on Form 4 Table I = shares. Table II = options and other derivatives.
Sources and method
| Source | Filings | Rows | First filed | Newest filed | Read the originals |
|---|---|---|---|---|---|
| SEC EDGAR, Form 4 | 6 | 26 | November 4, 2025 | August 17, 2026 | Form 4 list on EDGAR |
Site built October 22, 2026. Every row in the tables above links to its own filing. To quote a figure, use the Cite button at the top of the page; see how to cite and reuse.
Every row comes from the reporting owner's Form 4 as filed with the SEC (EDGAR ownership XML), read daily. "Value" is shares × the reported price; code P is an open-market purchase, S a sale, M an option exercise, A a grant. The lag is the filing date minus the trade date; Form 4 is due within two business days. Amendments (4/A) are not merged. Details on the methodology page; report an error on corrections.
Not investment advice. Figures are public disclosures shown as filed; they may lag the trade and may be amended later. No recommendation is made or implied.