The public view is the crawlable proof. The same sourced dataset is available through REST and MCP for agents, research scripts, and back-office tools.
| Date | Insider | Role | Action | Shares | Price | Value |
|---|---|---|---|---|---|---|
| Aug 31, 2026 | Darby Tommy | VP and CAO | Grant(A) | 2K | — | $0 |
| Aug 14, 2026 | Chao Catherine T. | Director | Grant(A) | 2K | — | $0 |
| Aug 14, 2026 | Chao David Tsung-Hung | Director | Grant(A) | 2K | — | $0 |
| Aug 14, 2026 | Cregg Roger A | Director | Grant(A) | 2K | — | $0 |
| Aug 14, 2026 | Northcutt R Bruce | Director | Grant(A) | 2K | — | $0 |
| Aug 14, 2026 | Patel Bhavesh V. | Director | Grant(A) | 2K | — | $0 |
| Aug 14, 2026 | Sabat Carolyn Chao | Director | Grant(A) | 2K | — | $0 |
| Aug 14, 2026 | Sheets Jeffrey Wayne | Director | Grant(A) | 2K | — | $0 |
| Aug 14, 2026 | Graff Michael J | Director | Grant(A) | 2K | — | $0 |
| Aug 14, 2026 | Lubel Kimberly S | Director | Grant(A) | 2K | — | $0 |
| Aug 14, 2026 | McCollum Mark A | Director | Grant(A) | 2K | — | $0 |
| Aug 11, 2026 | Chao Albert | Executive Chairman, Director | Option exercise(M) | 39K | $61.87 | $2.4M |
| Aug 11, 2026 | Chao Albert | Executive Chairman, Director | Sell(S) | 7K | $79.70 | $597K |
| Aug 11, 2026 | Chao Albert | Executive Chairman, Director | Sell(S) | 31K | $80.42 | $2.5M |
| Aug 11, 2026 | Chao Albert | Executive Chairman, Director | Option exercise(M) | 39K | — | $0 |
| Aug 8, 2026 | Sabat Carolyn Chao | Director | Option exercise(M) | 2K | — | — |
| Aug 8, 2026 | Graff Michael J | Director | Option exercise(M) | 2K | — | — |
| Aug 8, 2026 | Graff Michael J | Director | Option exercise(M) | 2K | — | $0 |
| Aug 8, 2026 | Cregg Roger A | Director | Option exercise(M) | 2K | — | — |
| Aug 8, 2026 | Cregg Roger A | Director | Option exercise(M) | 2K | — | $0 |
| Aug 8, 2026 | Chao Catherine T. | Director | Option exercise(M) | 2K | — | — |
| Aug 8, 2026 | McCollum Mark A | Director | Option exercise(M) | 2K | — | — |
| Aug 8, 2026 | McCollum Mark A | Director | Option exercise(M) | 2K | — | $0 |
| Aug 8, 2026 | Lubel Kimberly S | Director | Option exercise(M) | 2K | — | — |
| Aug 8, 2026 | Lubel Kimberly S | Director | Option exercise(M) | 2K | — | $0 |
| Aug 8, 2026 | Sheets Jeffrey Wayne | Director | Option exercise(M) | 2K | — | — |
| Aug 8, 2026 | Sheets Jeffrey Wayne | Director | Option exercise(M) | 2K | — | $0 |
| Aug 8, 2026 | Sabat Carolyn Chao | Director | Option exercise(M) | 2K | — | $0 |
| Aug 8, 2026 | Northcutt R Bruce | Director | Option exercise(M) | 2K | — | — |
| Aug 8, 2026 | Northcutt R Bruce | Director | Option exercise(M) | 2K | — | $0 |
| Aug 8, 2026 | Chao David Tsung-Hung | Director | Option exercise(M) | 2K | — | — |
| Aug 8, 2026 | Chao David Tsung-Hung | Director | Option exercise(M) | 2K | — | $0 |
| Aug 8, 2026 | Chao Catherine T. | Director | Option exercise(M) | 2K | — | $0 |
| Jun 15, 2026 | Baksht Jonathan | SVP and CFO | Grant(A) | 21K | — | $0 |
| May 13, 2026 | Bender Mark Steven | EVP & CFO | Tax withholding(F) | 5K | $97.34 | $514K |
| May 12, 2026 | Bender Mark Steven | EVP & CFO | Option exercise(M) | 13K | — | $0 |
| May 12, 2026 | Bender Mark Steven | EVP & CFO | Option exercise(M) | 13K | — | $0 |
| Apr 2, 2026 | Powers Brian John | SVP, PEM Segment Head | Grant(A) | 2K | — | $0 |
| Mar 27, 2026 | Bender Mark Steven | EVP & CFO | Sell(S) | 16K | $112.54 | $1.8M |
| Mar 27, 2026 | Buesinger Robert F. | EVP, PEM Segment Head | Sell(S) | 4K | $115.25 | $461K |
| Feb 27, 2026 | Bender Mark Steven | EVP & CFO | Option exercise(M) | 6K | $65.81 | $408K |
| Feb 27, 2026 | Bender Mark Steven | EVP & CFO | Sell(S) | 421 | $101.52 | $43K |
| Feb 27, 2026 | Bender Mark Steven | EVP & CFO | Sell(S) | 17K | $100.91 | $1.7M |
| Feb 27, 2026 | Bender Mark Steven | EVP & CFO | Disposed to issuer(D) | 13K | $98.20 | $1.2M |
| Feb 27, 2026 | Bender Mark Steven | EVP & CFO | Option exercise(M) | 6K | $86.54 | $562K |
| Feb 27, 2026 | Bender Mark Steven | EVP & CFO | Option exercise(M) | 6K | — | $0 |
| Feb 27, 2026 | Bender Mark Steven | EVP & CFO | Option exercise(M) | 6K | — | $0 |
| Feb 20, 2026 | Patel Bhavesh V. | Director | Grant(A) | 2K | — | $0 |
| Feb 20, 2026 | Chao James | Senior Chairman, Director | Tax withholding(F) | 2K | $94.10 | $148K |
| Feb 20, 2026 | Chao James | Senior Chairman, Director | Grant(A) | 27K | — | $0 |
| Feb 20, 2026 | Chao James | Senior Chairman, Director | Grant(A) | 7K | — | $0 |
| Feb 20, 2026 | Chao Albert | Executive Chairman, Director | Tax withholding(F) | 3K | $94.10 | $235K |
| Feb 20, 2026 | Chao Albert | Executive Chairman, Director | Grant(A) | 55K | — | $0 |
| Feb 20, 2026 | Chao Albert | Executive Chairman, Director | Grant(A) | 15K | — | $0 |
| Feb 20, 2026 | Chao John Tsung-chen | Director | Tax withholding(F) | 91 | $94.10 | $9K |
| Feb 20, 2026 | Chao John Tsung-chen | Director | Grant(A) | 2K | — | $0 |
| Feb 20, 2026 | Chao John Tsung-chen | Director | Grant(A) | 1K | — | $0 |
| Feb 20, 2026 | Chao John Tsung-chen | Director | Grant(A) | 4K | — | $0 |
| Feb 20, 2026 | Bender Mark Steven | EVP & CFO | Tax withholding(F) | 445 | $94.10 | $42K |
| Feb 20, 2026 | Bender Mark Steven | EVP & CFO | Grant(A) | 28K | — | $0 |
| Feb 20, 2026 | Bender Mark Steven | EVP & CFO | Grant(A) | 8K | — | $0 |
| Feb 20, 2026 | Buesinger Robert F. | EVP, PEM Segment Head | Tax withholding(F) | 326 | $94.10 | $31K |
| Feb 20, 2026 | Buesinger Robert F. | EVP, PEM Segment Head | Grant(A) | 5K | — | $0 |
| Feb 20, 2026 | Buesinger Robert F. | EVP, PEM Segment Head | Grant(A) | 19K | — | $0 |
| Feb 20, 2026 | Ederington L. Benjamin | EVP, Legal & External Affairs | Tax withholding(F) | 357 | $94.10 | $34K |
| Feb 20, 2026 | Ederington L. Benjamin | EVP, Legal & External Affairs | Grant(A) | 26K | — | $0 |
| Feb 20, 2026 | Ederington L. Benjamin | EVP, Legal & External Affairs | Grant(A) | 7K | — | $0 |
| Feb 20, 2026 | Gilson Jean-Marc | President and CEO | Grant(A) | 109K | — | $0 |
| Feb 20, 2026 | Gilson Jean-Marc | President and CEO | Grant(A) | 30K | — | $0 |
| Feb 20, 2026 | Holy Jeffrey Adam | VP and CAO | Tax withholding(F) | 81 | $94.10 | $8K |
| Feb 20, 2026 | Holy Jeffrey Adam | VP and CAO | Grant(A) | 1K | — | $0 |
| Feb 20, 2026 | Holy Jeffrey Adam | VP and CAO | Grant(A) | 3K | — | $0 |
| Feb 20, 2026 | Holy Jeffrey Adam | VP and CAO | Grant(A) | 4K | — | $0 |
| Feb 20, 2026 | Szwejbka Scott Thomas | SVP, HIP Segment Head | Tax withholding(F) | 91 | $94.10 | $9K |
| Feb 20, 2026 | Szwejbka Scott Thomas | SVP, HIP Segment Head | Grant(A) | 4K | — | $0 |
| Feb 20, 2026 | Szwejbka Scott Thomas | SVP, HIP Segment Head | Grant(A) | 15K | — | $0 |
| Feb 19, 2026 | Chao James | Senior Chairman, Director | Grant(A) | 4K | — | $0 |
| Feb 19, 2026 | Chao Albert | Executive Chairman, Director | Grant(A) | 6K | — | $0 |
| Feb 19, 2026 | Chao John Tsung-chen | Director | Grant(A) | 213 | — | $0 |
| Feb 19, 2026 | Bender Mark Steven | EVP & CFO | Grant(A) | 2K | — | $0 |
| Feb 19, 2026 | Buesinger Robert F. | EVP, PEM Segment Head | Grant(A) | 1K | — | $0 |
| Feb 19, 2026 | Ederington L. Benjamin | EVP, Legal & External Affairs | Grant(A) | 1K | — | $0 |
| Feb 19, 2026 | Holy Jeffrey Adam | VP and CAO | Grant(A) | 264 | — | $0 |
| Feb 19, 2026 | Szwejbka Scott Thomas | SVP, HIP Segment Head | Grant(A) | 365 | — | $0 |
| Feb 18, 2026 | Bender Mark Steven | EVP & CFO | Tax withholding(F) | 1K | $98.95 | $120K |
| Feb 18, 2026 | Buesinger Robert F. | EVP, PEM Segment Head | Tax withholding(F) | 903 | $98.95 | $89K |
| Feb 18, 2026 | Chao Albert | Executive Chairman, Director | Tax withholding(F) | 5K | $98.95 | $504K |
| Feb 18, 2026 | Chao John Tsung-chen | Director | Tax withholding(F) | 242 | $98.95 | $24K |
| Feb 18, 2026 | Chao James | Senior Chairman, Director | Tax withholding(F) | 3K | $98.95 | $264K |
| Feb 18, 2026 | Ederington L. Benjamin | EVP, Legal & External Affairs | Tax withholding(F) | 978 | $98.95 | $97K |
| Feb 18, 2026 | Holy Jeffrey Adam | VP and CAO | Tax withholding(F) | 213 | $98.95 | $21K |
| Feb 18, 2026 | Szwejbka Scott Thomas | SVP, HIP Segment Head | Tax withholding(F) | 295 | $98.95 | $29K |
| Feb 17, 2026 | Bender Mark Steven | EVP & CFO | Option exercise(M) | 5K | — | $0 |
| Feb 17, 2026 | Bender Mark Steven | EVP & CFO | Option exercise(M) | 5K | — | $0 |
| Feb 17, 2026 | Buesinger Robert F. | EVP, PEM Segment Head | Option exercise(M) | 3K | — | $0 |
| Feb 17, 2026 | Buesinger Robert F. | EVP, PEM Segment Head | Option exercise(M) | 3K | — | $0 |
| Feb 17, 2026 | Chao Albert | Executive Chairman, Director | Option exercise(M) | 17K | — | $0 |
| Feb 17, 2026 | Chao Albert | Executive Chairman, Director | Option exercise(M) | 17K | — | $0 |
| Feb 17, 2026 | Chao John Tsung-chen | Director | Option exercise(M) | 570 | — | $0 |
| Feb 17, 2026 | Chao John Tsung-chen | Director | Option exercise(M) | 570 | — | $0 |
Insider transactions sourced from SEC EDGAR Form 4 filings, normalized within minutes of acceptance. "Buy"/"Sell" mark open-market transactions (codes P/S), the tradeable signal. Awards, option exercises and tax-withholding are shown with their raw code. All data is public domain.
Coverage: Form 4 filings indexed 2006-01-02 → 2026-09-02. Earlier history is backfilling; this window widens as it deepens.
Programmatic access via the Arkolith API & MCP server (insider.transactions, insider.company).
Connected pages for WLK