Westlake Corporation (WLK) Insider Trading

Last 12 months

Insiders sold $10.2M and bought nothing on the open market.

None of the selling was scheduled in advance under a 10b5-1 plan. Executive Chairman Albert Chao sold $3.12M on Aug 11, 5.7% of their stake, outside a plan. The last open-market buy by an executive or director was in Apr 2025.

Net open-market

−$10.2M

0 buys · 5 sales

Under a 10b5-1 plan

of the value sold

Insiders who bought / sold

0 / 3

executives and directors

Last open-market buy

Apr 2025

Apr 22, 2025

Get an email when WLK's executives or directors buy, or make a large sale outside a plan.

Trades · last 2 years

Date	Insider	Trade	Shares	Price	Value	Of their stake	Filing
Aug 11	Albert Chao Executive Chairman	SoldNo plan 2 parts	38,873	$80.28 average	$3.12M	5.7%	Form 4
Mar 27	Robert F. Buesinger EVP, PEM Segment Head	SoldNo plan	4,000	$115.25	$461k	10%	Form 4
Mar 27	Mark Steven Bender EVP & CFO	SoldNo plan	16,413	$112.54	$1.85M	37%	Form 4
Feb 27	Mark Steven Bender EVP & CFO	SoldNo plan 2 parts	17,409	$100.92 average	$1.76M	28%	Form 4
Dec 22, 2025	Albert Chao Executive Chairman	SoldNo plan 3 parts	40,836	$73.58 average	$3M	6.1%	Form 4
May 27, 2025	Robert F. Buesinger EVP, PEM Segment Head	SoldNo plan	83	$72.70	$6k	0.2%	Form 4
Apr 22, 2025	Robert F. Buesinger EVP, PEM Segment Head	Bought	83	$93.39	$8k	0.2%	Form 4
Nov 29, 2024	David Tsung-Hung Chao Director	SoldNo plan	1,750	$129.08	$226k	6.0%	Form 4
Nov 22, 2024	David Tsung-Hung Chao Director	SoldNo plan	1,750	$130.00	$228k	5.7%	Form 4

Aug 11No plan
Albert Chao
Executive Chairman · sold 38,873 at avg $80.28
$3.12M
5.7% of stake
Mar 27No plan
Robert F. Buesinger
EVP, PEM Segment Head · sold 4,000 at $115.25
$461k
10% of stake
Mar 27No plan
Mark Steven Bender
EVP & CFO · sold 16,413 at $112.54
$1.85M
37% of stake
Feb 27No plan
Mark Steven Bender
EVP & CFO · sold 17,409 at avg $100.92
$1.76M
28% of stake
Dec 22, 2025No plan
Albert Chao
Executive Chairman · sold 40,836 at avg $73.58
$3M
6.1% of stake
May 27, 2025No plan
Robert F. Buesinger
EVP, PEM Segment Head · sold 83 at $72.70
$6k
0.2% of stake
Apr 22, 2025
Robert F. Buesinger
EVP, PEM Segment Head · bought 83 at $93.39
$8k
0.2% of stake
Nov 29, 2024No plan
David Tsung-Hung Chao
Director · sold 1,750 at $129.08
$226k
6.0% of stake
Nov 22, 2024No plan
David Tsung-Hung Chao
Director · sold 1,750 at $130.00
$228k
5.7% of stake

How to read this. Insiders sell for many reasons: taxes, diversifying, a house. Open-market buys are rarer and say more. A 10b5-1 plan is a trading schedule set up months in advance, so those sales were not timed on news. Large holders (funds and 10% owners) are listed under Everything but not counted as insiders. If you own or watch WLK, we send a push when an executive buys or makes a large sale outside a plan.

Source: SEC Form 4 filings, filed within two business days of each trade and checked for new ones every hour.

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Spot a number that looks wrong? Check it in WLK's SEC filings or

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Data sourced from SEC EDGAR filings and third-party price providers. Scores, valuations, and metrics are algorithmic estimates. This is not investment advice. See our Terms and Methodology.

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