Recent insider transactions reported to the SEC on Form 4 — directors and officers buying or selling their own company’s stock. Sourced directly from public SEC filings, latest filed Sep 1, 2026.
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Counts cover the 40 most recent Form 4 filings Tradune holds for WLK (filed Feb 19 – Sep 1, 2026); the score below covers only the trailing 90 days (0 buys, 2 sells). No completed check of WLK's Form 4 list on SEC EDGAR is on record yet; the latest WLK filing Tradune holds was filed Sep 1, 2026. This is not guaranteed to be the complete record — see WLK's full Form 4 filing history on SEC EDGAR.
Open-market activity, last 90 days
Purchases (Form 4 code P) and sales (code S) on the 21 filings Tradune holds for WLK filed Aug 10 – Sep 1, 2026. Grants, exercises, tax withholding and the other Form 4 transaction codes are left out.
filed before Apr 1, 2023, or no checkbox value in the filing data
Counts are Form 4 lines as filed. The checkbox is one per filing, so every sale on a filing with the box checked is counted there even if only some of its transactions were under a plan; it records what the filer disclosed, and the three categories are not a judgement about why a sale was made.
Open-market purchases and sales by insider
Insider
Buys
Sells
Shares bought
Shares sold
Value
Albert ChaoExecutive Chairman
0
2
—
38,873
−$3,120,775
Value = shares × the price reported on each Form 4 (+ purchases, − sales); every open-market line in this window disclosed a price.
Insider-activity score
0/ 100
Net insider sales
0 distinct buyers0 buy · 2 sell tx
Summarises ~90 days of public SEC Form 4 activity — more distinct buyers, officer involvement and net buying score higher. A description of filing activity, not a rating or buy signal. How this score is computed →
How to read this: an open-market purchase (Form 4 code P) is a buy at the market price with the insider’s own money, as opposed to a grant, award or option exercise; an open-market sale is code S. When two or more distinct insiders report open-market purchases in the same 90-day window, this site labels that a cluster — a definition, not a forecast; see insider cluster buying.
“Held after” is Form 4 Table I column 5; “Change” = shares ÷ holdings before the trade (held after − shares for an acquisition, held after + shares for a disposition).
Insider Buying at WLK
No open-market insider purchases (Form 4 code P) were reported for WLK between Feb 19, 2026 and Sep 1, 2026. The filings below may include other transaction types — sales, grants, option exercises, and tax withholding — shown for completeness; they are not open-market purchases.
† change in this filer’s own reported holding line (Form 4 Table I, col. 5), not of total company ownership; small prior holdings produce large percentages, so under 100 shares the prior holding is shown instead.
“10b5-1 box checked” = the filer checked the Form 4 box stating that a transaction on the filing was made under a plan intended to satisfy Rule 10b5-1(c); “10b5-1 box not checked” = the box was left blank, which does not prove that no plan exists. The box applies to Form 4s filed from April 1, 2023; older filings, and boxes we could not read, carry no tag. What the 10b5-1 box means.
Listing the 25 most recent of 40 Form 4 filings held for WLK; the 15 older filings (filed Feb 19 – Mar 30, 2026) are counted above but not listed here — see WLK's full Form 4 filing history on SEC EDGAR.
Insider filings reported around the same time
Other companies whose most recent Form 4 was filed closest to WLK's (Sep 1, 2026).
How many insiders bought WLK stock in these Form 4 filings?
No open-market purchases (Form 4 code P) of WLK shares were reported by Westlake Corp insiders between Feb 19, 2026 and Sep 1, 2026. The 40 filings shown on this page cover other transaction types — sales, grants, option exercises, and tax withholding.
Who filed the most recent Form 4 for WLK?
The most recent Form 4 on this page was filed by Tommy Darby (VP and CAO) on Sep 1, 2026, reporting 1 transaction. The original document is linked from the filing list above on SEC EDGAR. Amended filings (Form 4/A) may later revise reported figures.
What was the largest open-market WLK insider sale shown?
The largest open-market sale among the filings shown was 31,384 WLK shares at $80.42 (about $2,523,901) by Albert Chao (Executive Chairman) on Aug 11, 2026. Value is shares × the price reported on the Form 4; its Rule 10b5-1 box is not checked.
New to Form 4s? The transaction codes, the 90-day window and the 0–100 score are defined on the insider-activity score methodology page.
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This score summarizes SEC Form 4 filing activity over the trailing 90 days. It is descriptive, not predictive — not a rating, recommendation, or investment advice. Data: SEC EDGAR (public domain), as filed; amendments may revise figures. Tradune is not a registered investment adviser.
Data as filed; amended filings (Form 4/A) may revise figures. Sales may occur under prearranged Rule 10b5-1 trading plans.