Westlake Corp (WLK) · Insider trading

What Westlake's directors, officers and largest holders bought and sold themselves, from the Form 4 each of them files with the SEC within two business days of a trade. Open-market purchases and sales first: those are the trades somebody chose to make at the market price.

Bought, 12 months

0 insiders, 0 trades

Sold, 12 months

$10.19M

3 insiders, 0% under a plan

Net, 12 months

−$10.19M

bought less sold

Latest filing

2026-08-11

filings read to 2026-10-20

Bought and sold at the market, by month

Two years. Purchases above the line, sales below, in dollars.

Bought Sold Largest month: $3.12M

Who traded, two years

Insider	Bought	Sold	Trades	Last trade	Holds after
Chao AlbertDirector, Executive Chairman	–	$6.13M	5	2026-08-11	674,264
Bender Mark StevenEVP & CFO	–	$3.60M	3	2026-03-27	28,015
Buesinger Robert F.EVP, PEM Segment Head	$7,751	$467,034	3	2026-03-27	34,482
Chao David Tsung-HungDirector	–	$453,390	2	2024-11-29	7,784

Open-market purchases and sales

Newest first. “Plan” marks a trade made under a 10b5-1 plan set up in advance.

Date	Insider	Trade	Shares	Price	Value	Holds after	Filing
2026-08-11	Chao AlbertDirector, Executive Chairman	Sale	7,489	79.70	$596,873	674,264	Form 4
2026-08-11	Chao AlbertDirector, Executive Chairman	Sale	31,384	80.42	$2.52M	642,880	Form 4
2026-03-27	Buesinger Robert F.EVP, PEM Segment Head	Sale	4,000	115.25	$461,000	34,482	Form 4
2026-03-27	Bender Mark StevenEVP & CFO	Sale	16,413	112.54	$1.85M	28,015	Form 4
2026-02-27	Bender Mark StevenEVP & CFO	Sale	16,988	100.91	$1.71M	44,854	Form 4
2026-02-27	Bender Mark StevenEVP & CFO	Sale	421	101.52	$42,740	44,433	Form 4
2025-12-22	Chao AlbertDirector, Executive Chairman	Sale	9,711	72.82	$707,155	658,847	Form 4
2025-12-22	Chao AlbertDirector, Executive Chairman	Sale	30,604	73.80	$2.26M	628,243	Form 4
2025-12-22	Chao AlbertDirector, Executive Chairman	Sale	521	74.44	$38,783	627,722	Form 4
2025-05-27	Buesinger Robert F.EVP, PEM Segment Head	Saleindirect	83	72.70	$6,034	0	Form 4
2025-04-22	Buesinger Robert F.EVP, PEM Segment Head	Buyindirect	83	93.39	$7,751	83	Form 4
2024-11-29	Chao David Tsung-HungDirector	Sale	1,750	129.08	$225,890	7,784	Form 4
2024-11-22	Chao David Tsung-HungDirector	Sale	1,750	130.00	$227,500	9,534	Form 4

Grants, exercises and other transactions

Pay, tax and paperwork rather than a choice to trade at the market price. Two years.

43 × shares withheld for tax42 × option exercise16 × grant or award1 × returned to the company1 × gift

Show them

Date	Insider	What	Shares	Price	Holds after	Filing
2026-08-11	Chao AlbertDirector, Executive Chairman	Option exercise M	+38,873	61.87	681,753	Form 4
2026-08-08	Chao Catherine T.Director	Option exercise M	+2,168	–	7,748	Form 4
2026-08-08	Chao David Tsung-HungDirector	Option exercise M	+2,168	–	11,080	Form 4
2026-08-08	Cregg Roger ADirector	Option exercise M	+2,168	–	3,507	Form 4
2026-08-08	Graff Michael JDirector	Option exercise M	+2,168	–	23,310	Form 4
2026-08-08	Lubel Kimberly SDirector	Option exercise M	+2,168	–	13,821	Form 4
2026-08-08	McCollum Mark ADirector	Option exercise M	+2,168	–	11,824	Form 4
2026-08-08	Northcutt R BruceDirector	Option exercise M	+2,168	–	23,351	Form 4
2026-08-08	Sabat Carolyn ChaoDirector	Option exercise M	+2,168	–	5,748	Form 4
2026-08-08	Sheets Jeffrey WayneDirector	Option exercise M	+2,168	–	14,927	Form 4
2026-05-13	Bender Mark StevenEVP & CFO	Shares withheld for tax F	−5,284	97.34	35,895	Form 4
2026-05-12	Bender Mark StevenEVP & CFO	Option exercise M	+13,164	–	41,179	Form 4
2026-02-27	Bender Mark StevenEVP & CFO	Option exercise M	+6,199	65.81	68,041	Form 4
2026-02-27	Bender Mark StevenEVP & CFO	Option exercise M	+6,494	86.54	74,535	Form 4
2026-02-27	Bender Mark StevenEVP & CFO	Returned to the company D	−12,693	98.20	61,842	Form 4
2026-02-20	Chao JamesDirector, Senior Chairman	Shares withheld for tax F	−1,569	94.10	49,774	Form 4
2026-02-20	Chao AlbertDirector, Executive Chairman	Shares withheld for tax F	−2,501	94.10	642,880	Form 4
2026-02-20	Chao John Tsung-chenDirector	Shares withheld for tax F	−91	94.10	7,888	Form 4
2026-02-20	Bender Mark StevenEVP & CFO	Shares withheld for tax F	−445	94.10	61,842	Form 4
2026-02-20	Buesinger Robert F.EVP, PEM Segment Head	Shares withheld for tax F	−326	94.10	38,482	Form 4
2026-02-20	Ederington L. BenjaminEVP, Legal & External Affairs	Shares withheld for tax F	−357	94.10	80,158	Form 4
2026-02-20	Holy Jeffrey AdamVP and CAO	Shares withheld for tax F	−81	94.10	5,124	Form 4
2026-02-20	Szwejbka Scott ThomasSVP, HIP Segment Head	Shares withheld for tax F	−91	94.10	13,773	Form 4
2026-02-19	Chao JamesDirector, Senior Chairman	Grant or award A	+3,884	–	51,343	Form 4
2026-02-19	Chao AlbertDirector, Executive Chairman	Grant or award A	+6,193	–	645,381	Form 4
2026-02-19	Chao John Tsung-chenDirector	Grant or award A	+213	–	7,979	Form 4
2026-02-19	Bender Mark StevenEVP & CFO	Grant or award A	+1,777	–	62,287	Form 4
2026-02-19	Buesinger Robert F.EVP, PEM Segment Head	Grant or award A	+1,301	–	38,808	Form 4
2026-02-19	Ederington L. BenjaminEVP, Legal & External Affairs	Grant or award A	+1,425	–	80,515	Form 4
2026-02-19	Holy Jeffrey AdamVP and CAO	Grant or award A	+264	–	5,205	Form 4
2026-02-19	Szwejbka Scott ThomasSVP, HIP Segment Head	Grant or award A	+365	–	13,864	Form 4
2026-02-18	Bender Mark StevenEVP & CFO	Shares withheld for tax F	−1,209	98.95	60,510	Form 4
2026-02-18	Buesinger Robert F.EVP, PEM Segment Head	Shares withheld for tax F	−903	98.95	37,507	Form 4
2026-02-18	Chao AlbertDirector, Executive Chairman	Shares withheld for tax F	−5,089	98.95	639,188	Form 4
2026-02-18	Chao John Tsung-chenDirector	Shares withheld for tax F	−242	98.95	7,766	Form 4
2026-02-18	Chao JamesDirector, Senior Chairman	Shares withheld for tax F	−2,664	98.95	47,459	Form 4
2026-02-18	Ederington L. BenjaminEVP, Legal & External Affairs	Shares withheld for tax F	−978	98.95	79,090	Form 4
2026-02-18	Holy Jeffrey AdamVP and CAO	Shares withheld for tax F	−213	98.95	4,941	Form 4
2026-02-18	Szwejbka Scott ThomasSVP, HIP Segment Head	Shares withheld for tax F	−295	98.95	13,499	Form 4
2026-02-17	Bender Mark StevenEVP & CFO	Option exercise M	+4,751	–	61,719	Form 4
2026-02-17	Buesinger Robert F.EVP, PEM Segment Head	Option exercise M	+3,478	–	38,410	Form 4
2026-02-17	Chao AlbertDirector, Executive Chairman	Option exercise M	+16,555	–	644,277	Form 4
2026-02-17	Chao John Tsung-chenDirector	Option exercise M	+570	–	7,608	Form 4
2026-02-17	Chao JamesDirector, Senior Chairman	Option exercise M	+10,382	–	50,123	Form 4
2026-02-17	Ederington L. BenjaminEVP, Legal & External Affairs	Option exercise M	+3,809	–	80,068	Form 4
2026-02-17	Holy Jeffrey AdamVP and CAO	Option exercise M	+706	–	5,154	Form 4
2026-02-17	Szwejbka Scott ThomasSVP, HIP Segment Head	Option exercise M	+977	–	13,794	Form 4
2025-12-22	Chao AlbertDirector, Executive Chairman	Option exercise M	+81,673	44.42	668,558	Form 4
2025-12-10	Cregg Roger ADirector	Option exercise M	+1,339	–	1,339	Form 4
2025-10-02	Szwejbka Scott ThomasSVP, HIP Segment Head	Shares withheld for tax F	−3,842	76.70	12,817	Form 4
2025-10-01	Szwejbka Scott ThomasSVP, HIP Segment Head	Option exercise M	+10,840	–	16,659	Form 4
2025-08-28	Chao JamesDirector, Senior Chairman	Gift G	−15,140	–	39,741	Form 4
2025-08-09	McCollum Mark ADirector	Option exercise M	+1,128	–	9,656	Form 4
2025-08-09	Northcutt R BruceDirector	Option exercise M	+1,128	–	21,183	Form 4
2025-08-09	Sheets Jeffrey WayneDirector	Option exercise M	+1,128	–	12,759	Form 4
2025-08-09	Lubel Kimberly SDirector	Option exercise M	+1,128	–	11,653	Form 4
2025-08-09	Graff Michael JDirector	Option exercise M	+1,128	–	21,142	Form 4
2025-08-09	Chao David Tsung-HungDirector	Option exercise M	+1,128	–	8,912	Form 4
2025-08-09	Sabat Carolyn ChaoDirector	Option exercise M	+1,128	–	3,580	Form 4
2025-08-09	Chao Catherine T.Director	Option exercise M	+1,128	–	5,580	Form 4
2025-03-05	Chao John Tsung-chenDirector	Shares withheld for tax F	−391	108.62	7,038	Form 4/A
2025-02-21	Bender Mark StevenEVP & CFO	Shares withheld for tax F	−3,530	110.54	56,968	Form 4
2025-02-21	Buesinger Robert F.EVP, HIP, IT & Digital	Shares withheld for tax F	−2,738	110.54	34,932	Form 4
2025-02-21	Chao AlbertDirector, Executive Chairman	Shares withheld for tax F	−13,390	110.54	586,885	Form 4
2025-02-21	Chao JamesDirector, Senior Chairman	Shares withheld for tax F	−6,554	110.54	54,881	Form 4
2025-02-21	Janssens Thomas J.SVP, Ops - PEM & Corp Logistic	Shares withheld for tax F	−606	110.54	17,127	Form 4
2025-02-21	Ederington L. BenjaminEVP, PEM, GC and CAO	Shares withheld for tax F	−2,924	110.54	76,259	Form 4
2025-02-21	Holy Jeffrey AdamVP and CAO	Shares withheld for tax F	−341	110.54	4,448	Form 4
2025-02-20	Chao John Tsung-chenDirector	Grant or award A	+955	–	7,664	Form 4/A
2025-02-20	Bender Mark StevenEVP & CFO	Grant or award A	+8,819	–	60,498	Form 4
2025-02-20	Buesinger Robert F.EVP, HIP, IT & Digital	Grant or award A	+6,839	–	37,670	Form 4
2025-02-20	Chao AlbertDirector, Executive Chairman	Grant or award A	+33,456	–	600,275	Form 4
2025-02-20	Chao JamesDirector, Senior Chairman	Grant or award A	+16,375	–	61,435	Form 4
2025-02-20	Janssens Thomas J.SVP, Ops - PEM & Corp Logistic	Grant or award A	+2,444	–	17,733	Form 4
2025-02-20	Ederington L. BenjaminEVP, PEM, GC and CAO	Grant or award A	+7,305	–	79,183	Form 4
2025-02-20	Holy Jeffrey AdamVP and CAO	Grant or award A	+1,306	–	4,789	Form 4
2025-02-19	Chao AlbertDirector, Executive Chairman	Shares withheld for tax F	−5,820	111.46	567,068	Form 4
2025-02-19	Chao AlbertDirector, Executive Chairman	Shares withheld for tax F	−249	112.73	566,819	Form 4
2025-02-19	Chao JamesDirector, Senior Chairman	Shares withheld for tax F	−2,193	111.46	45,154	Form 4
2025-02-19	Chao JamesDirector, Senior Chairman	Shares withheld for tax F	−94	112.76	45,060	Form 4
2025-02-19	Holy Jeffrey AdamVP and CAO	Shares withheld for tax F	−210	111.46	3,492	Form 4
2025-02-19	Holy Jeffrey AdamVP and CAO	Shares withheld for tax F	−9	112.76	3,483	Form 4
2025-02-19	Janssens Thomas J.SVP, Ops - PEM & Corp Logistic	Shares withheld for tax F	−322	111.46	15,303	Form 4
2025-02-19	Janssens Thomas J.SVP, Ops - PEM & Corp Logistic	Shares withheld for tax F	−14	112.53	15,289	Form 4
2025-02-19	Bender Mark StevenEVP & CFO	Shares withheld for tax F	−4,264	111.46	51,861	Form 4
2025-02-19	Bender Mark StevenEVP & CFO	Shares withheld for tax F	−50	112.46	51,811	Form 4
2025-02-19	Bender Mark StevenEVP & CFO	Shares withheld for tax F	−132	112.76	51,679	Form 4
2025-02-19	Buesinger Robert F.EVP, HIP, IT & Digital	Shares withheld for tax F	−3,851	111.46	30,995	Form 4
2025-02-19	Buesinger Robert F.EVP, HIP, IT & Digital	Shares withheld for tax F	−164	112.76	30,831	Form 4
2025-02-19	Ederington L. BenjaminEVP, PEM, GC and CAO	Shares withheld for tax F	−5,052	111.46	72,094	Form 4
2025-02-19	Ederington L. BenjaminEVP, PEM, GC and CAO	Shares withheld for tax F	−216	112.76	71,878	Form 4
2025-02-18	Chao John Tsung-chenDirector	Option exercise M	+513	–	6,709	Form 4/A
2025-02-18	Chao AlbertDirector, Executive Chairman	Option exercise M	+17,972	–	572,888	Form 4
2025-02-18	Chao JamesDirector, Senior Chairman	Option exercise M	+8,796	–	47,347	Form 4
2025-02-18	Holy Jeffrey AdamVP and CAO	Option exercise M	+702	–	3,702	Form 4
2025-02-18	Janssens Thomas J.SVP, Ops - PEM & Corp Logistic	Option exercise M	+1,313	–	15,625	Form 4
2025-02-18	Bender Mark StevenEVP & CFO	Option exercise M	+13,987	–	56,125	Form 4
2025-02-18	Buesinger Robert F.EVP, HIP, IT & Digital	Option exercise M	+12,923	–	34,846	Form 4
2025-02-18	Ederington L. BenjaminEVP, PEM, GC and CAO	Option exercise M	+13,174	–	77,146	Form 4
2025-02-18	Ederington L. BenjaminEVP, PEM, GC and CAO	Shares withheld for tax F	−1,895	115.29	63,972	Form 4
2025-02-18	Janssens Thomas J.SVP, Ops - PEM & Corp Logistic	Shares withheld for tax F	−790	115.29	14,312	Form 4
2025-02-14	Ederington L. BenjaminEVP, PEM, GC and CAO	Option exercise M	+7,597	–	65,867	Form 4
2025-02-14	Janssens Thomas J.SVP, Ops - PEM & Corp Logistic	Option exercise M	+3,039	–	15,102	Form 4

How to read it

Buy, sale: Code P and S on the form: shares bought or sold in the market, at the market price. The other codes are mostly pay (a grant, an option exercised) or tax (shares the company withheld), and say little about what the insider thinks of the price.
Plan: A sale or purchase under a Rule 10b5-1 plan, set up in advance and running on its own schedule. Since April 2023 the form has a box for it. Much executive selling is planned and says more about diversifying than about the company.
Holds after: The shares the insider still held after the trade, in the form the trade was in (directly, or indirectly through a trust or a fund).
Value: Shares times the price the form reports, which is often an average over several fills on the day.

Read from the SEC's own quarterly data sets of Forms 3, 4 and 5, and from each day's filings since the last one. A correcting amendment replaces the lines it restates. Every row links to its filing. None of this is advice: insiders sell for many reasons, and buy for fewer.

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