SEC Form 4
Westlake Corporation (WLK) insider trading
In the 12 months to Oct 23, 2026, 3 WLK insiders reported open-market sales of $10.2M across 5 filings; no open-market purchases were filed.
Latest filing · Last 12 months · Source: SEC EDGAR · How we count
- Open-market sales
- $10.2M
- 5 filings · 3 insiders
- Open-market purchases
- $0
- 0 filings
Who traded WLK, and when
- Sale
WLK daily close from Oct 23, 2025 to Oct 23, 2026, between $56.38 and $123.39, last $64.56. 5 sale and 0 purchase filings by 3 insiders, marked at their filing dates. Albert Chao, Executive Chairman: sold $6.1M across 2 filings, first filed Dec 23, 2025, last Aug 11, 2026. Mark Steven Bender, EVP & CFO: sold $3.6M across 2 filings, first filed Mar 2, 2026, last Mar 30, 2026. Robert F. Buesinger, EVP, PEM Segment Head: sold $461.0K across 1 filing, first filed Mar 31, 2026, last Mar 31, 2026.
Largest mark · tap a row for others
Albert Chao · Executive Chairman
Sale $3,120,775
38,873 shares at $80.28 avg
Filed Aug 11, 2026
Close on filing date $80.84
Albert Chao · Executive Chairman
Executive Chairman
$6.1M soldMark Steven Bender · EVP & CFO
EVP & CFO
$3.6M soldRobert F. Buesinger · EVP, PEM Segment Head
EVP, PEM Segment Head
$461.0K soldHas the Westlake Corporation's CEO sold stock?
No. Jean-Marc Gilson (CEO) made no open-market sales filed as CEO in the last 12 months.
Open-market trades
5 filings in the last 12 months| Insider | Role | Sold | Bought | Filings | Pre-arranged (10b5-1) | Last filed |
|---|---|---|---|---|---|---|
| Albert Chao | Executive Chairman | $6.1M | — | 2 | — | |
| Mark Steven Bender | EVP & CFO | $3.6M | — | 2 | — | |
| Robert F. Buesinger | EVP, PEM Segment Head | $461.0K | — | 1 | — |
| Filed | Insider | Type | Shares | Avg price | Value | Held after | Source |
|---|---|---|---|---|---|---|---|
traded | Albert Chao Executive Chairman | Sale | 38,873 | $80.28 | $3.1M | 674,264 | |
traded | Robert F. Buesinger EVP, PEM Segment Head | Sale | 4,000 | $115.25 | $461.0K | 34,482 | |
traded | Mark Steven Bender EVP & CFO | Sale | 16,413 | $112.54 | $1.8M | 28,015 | |
traded | Mark Steven Bender EVP & CFO | Sale | 17,409 | $100.92 | $1.8M | 44,854 | |
traded | Albert Chao Executive Chairman | Sale | 40,836 | $73.57 | $3.0M | 658,847 |
GET /stocks/filings/vX/form-4?tickers=WLK&filing_date.gte=2025-10-23&sort=filing_date.desc&limit=500{
"status": "OK",
"results": [
{
"tickers": [
"WLK"
],
"issuer_cik": "0001262823",
"owner_cik": "0001299403",
"accession_number": "0001193125-26-345140",
"form_type": "4",
"filing_date": "2026-08-11",
"period_of_report": "2026-08-11",
"issuer_name": "WESTLAKE CORP",
"issuer_trading_symbol": "WLK",
"owner_name": "Chao Albert",
"is_director": true,
"is_officer": true,
"is_ten_percent_owner": false,
"is_other": false,
"officer_title": "Executive Chairman",
"security_type": "non_derivative",
"record_type": "transaction",
"security_title": "Common Stock",
"transaction_timeliness": "O",
"aff_10b5_one": false,
"transaction_date": "2026-08-11",
"transaction_code": "S",
"equity_swap_involved": false,
"transaction_shares": 31384,
"transaction_price_per_share": 80.42,
"transaction_acquired_disposed": "D",
"shares_owned_following_transaction": 642880,
"transaction_value": 2523901.2800000003,
"not_subject_to_section_16": false,
"direct_or_indirect": "D",
"footnotes": [
{
"id": "F2",
"description": "Weighted average price. These shares were sold in multiple transactions ranging from $80.10 to $80.86 inclusive. The reporting person undertakes to provide the issuer, any security holder of the issuer, or the staff of the SEC, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."
}
]
},
{
"tickers": [
"WLK"
],
"issuer_cik": "0001262823",
"owner_cik": "0001299403",
"accession_number": "0001193125-26-345140",
"form_type": "4",
"filing_date": "2026-08-11",
"period_of_report": "2026-08-11",
"issuer_name": "WESTLAKE CORP",
"issuer_trading_symbol": "WLK",
"owner_name": "Chao Albert",
"is_director": true,
"is_officer": true,
"is_ten_percent_owner": false,
"is_other": false,
"officer_title": "Executive Chairman",
"security_type": "non_derivative",
"record_type": "transaction",
"security_title": "Common Stock",
"transaction_timeliness": "O",
"aff_10b5_one": false,
"transaction_date": "2026-08-11",
"transaction_code": "S",
"equity_swap_involved": false,
"transaction_shares": 7489,
"transaction_price_per_share": 79.7,
"transaction_acquired_disposed": "D",
"shares_owned_following_transaction": 674264,
"transaction_value": 596873.3,
"not_subject_to_section_16": false,
"direct_or_indirect": "D",
"footnotes": [
{
"id": "F1",
"description": "Weighted average price. These shares were sold in multiple transactions ranging from $79.02 to $80.01 inclusive. The reporting person undertakes to provide the issuer, any security holder of the issuer, or the staff of the SEC, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."
}
]
}
]
}
// trimmed to 2 resultsThe response includes every Form 4 record; this page keeps open-market purchases and sales on common stock and removes duplicate joint-filer rows.
Other insider activity (not market trades) · 50 records
- Option exercises23 records
- Tax withholding18 records
- Grants and awards8 records
- Other1 record
Reported on Form 4 but not purchases or sales in the market, so not counted in the totals above.
Build this yourself
This page joins two Massive endpoints: Form 4 filings and daily prices. Ask an agent to watch for new filings:
Using the Massive API (massive.com/docs/llms.txt), check Form 4 filings for WLK every day with transaction_code=P and tell me when an insider files an open-market purchase, with their role, shares, price and the filing link.
How to read this page
- Open-market purchase or sale
- A buy or sell of the company's stock at market price. Grants, option exercises, shares withheld for tax, gifts and employee stock plan purchases are listed separately and not counted.
- Filing date
- Insiders have two business days to report a trade. Totals and the chart use the filing date, when the trade became public.