Westlake's three largest insider shareholders as of September 29, 2026 are Albert Chao (Executive Chairman, 642.88K shares), L. Benjamin Ederington (Evp, Legal External Affairs, 80.16K shares), Dorothy C Jenkins (Director, 73.78K shares).
| # | Insider | Position | Direct | Indirect | Total | Share of Insiders | Last Filed |
|---|---|---|---|---|---|---|---|
| 1 | Albert Chao | Executive Chairman | 642,880 | 0 | 642,880 | 55.8% | 11 Aug, 2026 |
| 2 | L. Benjamin Ederington | Evp, Legal External Affairs | 80,158 | 0 | 80,158 | 7.0% | 23 Feb, 2026 |
| 3 | Dorothy C Jenkins | Director, TenPercentOwner | 73,778 | 0 | 73,778 | 6.4% | 15 Aug, 2022 |
| 4 | James Chao | Senior Chairman | 49,774 | 0 | 49,774 | 4.3% | 23 Feb, 2026 |
| 5 | Roger L. Kearns | Coo And Evp, Pem | 39,849 | 0 | 39,849 | 3.5% | 15 Mar, 2023 |
| 6 | Mark Steven Bender | Evp Cfo | 35,895 | 0 | 35,895 | 3.1% | 14 May, 2026 |
| 7 | Robert F. Buesinger | Evp, Pem Segment Head | 34,482 | 0 | 34,482 | 3.0% | 31 Mar, 2026 |
| 8 | R Bruce Northcutt | Director | 23,351 | 0 | 23,351 | 2.0% | 10 Aug, 2026 |
| 9 | Michael J Graff | Director | 23,310 | 0 | 23,310 | 2.0% | 10 Aug, 2026 |
| 10 | Andrew Kenner | Svp, Operations | 20,362 | 0 | 20,362 | 1.8% | 22 Feb, 2022 |
| 11 | Thomas J. Janssens | Svp, Ops Pem Corp Logistic | 17,127 | 0 | 17,127 | 1.5% | 24 Feb, 2025 |
| 12 | Jeffrey Wayne Sheets | Director | 14,927 | 0 | 14,927 | 1.3% | 10 Aug, 2026 |
| 13 | Kimberly S Lubel | Director | 13,821 | 0 | 13,821 | 1.2% | 10 Aug, 2026 |
| 14 | Scott Thomas Szwejbka | Svp, Hip Segment Head | 13,773 | 0 | 13,773 | 1.2% | 23 Feb, 2026 |
| 15 | Mark A Mccollum | Director | 11,824 | 0 | 11,824 | 1.0% | 10 Aug, 2026 |
| 16 | Marius Haas | Director | 11,631 | 0 | 11,631 | 1.0% | 12 Aug, 2024 |
| 17 | David Tsung-Hung Chao | Director | 11,080 | 0 | 11,080 | 1.0% | 10 Aug, 2026 |
| 18 | John Tsung-Chen Chao | Director | 7,888 | 0 | 7,888 | 0.7% | 23 Feb, 2026 |
| 19 | Catherine T. Chao | Director | 7,748 | 0 | 7,748 | 0.7% | 10 Aug, 2026 |
| 20 | Carolyn Chao Sabat | Director | 5,748 | 0 | 5,748 | 0.5% | 10 Aug, 2026 |
| 21 | Jeffrey Adam Holy | Vp And Cao | 5,124 | 0 | 5,124 | 0.4% | 23 Feb, 2026 |
| 22 | Johnathan Stevan Zoeller | Vp And Cao | 4,416 | 0 | 4,416 | 0.4% | 22 Mar, 2024 |
| 23 | Roger A Cregg | Director | 3,507 | 0 | 3,507 | 0.3% | 10 Aug, 2026 |
Each row is that insider’s most recently reported position, from Form 4 filings over the last 60 months — which is why this total does not tie to the quarterly series above, where a quarter counts only the insiders who filed in it. Shares held through a fund or institutional portfolio are counted on the institutional ownership page instead.
| Date | Insider | Position | Transaction | Shares | Price | Value | Shares Held After | Ownership |
|---|---|---|---|---|---|---|---|---|
| 31 Aug, 2026 | Tommy Darby | Vp And Cao | Acquired A | 1,791 | $0.00 | $0 | 1,791 | Direct |
| 14 Aug, 2026 | Mark A Mccollum | Director | Acquired A | 2,184 | $0.00 | $0 | 2,184 | Direct |
| 14 Aug, 2026 | Kimberly S Lubel | Director | Acquired A | 2,184 | $0.00 | $0 | 2,184 | Direct |
| 14 Aug, 2026 | David Tsung-Hung Chao | Director | Acquired A | 2,184 | $0.00 | $0 | 2,184 | Direct |
| 14 Aug, 2026 | Roger A Cregg | Director | Acquired A | 2,184 | $0.00 | $0 | 2,184 | Direct |
| 14 Aug, 2026 | Michael J Graff | Director | Acquired A | 2,184 | $0.00 | $0 | 2,184 | Direct |
| 14 Aug, 2026 | Bhavesh V. Patel | Director | Acquired A | 2,184 | $0.00 | $0 | 2,184 | Direct |
| 14 Aug, 2026 | Carolyn Chao Sabat | Director | Acquired A | 2,184 | $0.00 | $0 | 2,184 | Direct |
| 14 Aug, 2026 | R Bruce Northcutt | Director | Acquired A | 2,184 | $0.00 | $0 | 2,184 | Direct |
| 14 Aug, 2026 | Catherine T. Chao | Director | Acquired A | 2,184 | $0.00 | $0 | 2,184 | Direct |
| 14 Aug, 2026 | Jeffrey Wayne Sheets | Director | Acquired A | 2,184 | $0.00 | $0 | 2,184 | Direct |
| 11 Aug, 2026 | Albert Chao | Executive Chairman | Acquired M | 38,873 | $61.87 | $2.40Mn | 681,753 | Direct |
| 11 Aug, 2026 | Albert Chao | Executive Chairman | Disposed S | 7,489 | $79.70 | $596.87K | 674,264 | Direct |
| 11 Aug, 2026 | Albert Chao | Executive Chairman | Disposed S | 31,384 | $80.42 | $2.52Mn | 642,880 | Direct |
| 11 Aug, 2026 | Albert Chao | Executive Chairman | Disposed M | 38,873 | $0.00 | $0 | 38,873 | Direct |
| 08 Aug, 2026 | Jeffrey Wayne Sheets | Director | Acquired M | 2,168 | — | — | 14,927 | Direct |
| 08 Aug, 2026 | Roger A Cregg | Director | Acquired M | 2,168 | — | — | 3,507 | Direct |
| 08 Aug, 2026 | Carolyn Chao Sabat | Director | Acquired M | 2,168 | — | — | 5,748 | Direct |
| 08 Aug, 2026 | David Tsung-Hung Chao | Director | Acquired M | 2,168 | — | — | 11,080 | Direct |
| 08 Aug, 2026 | Mark A Mccollum | Director | Acquired M | 2,168 | — | — | 11,824 | Direct |