What SEC filings does Westlake Corporation submit to the SEC?

Westlake Corporation (WLK) submits several types of SEC filings including Form 4 (insider transactions), Form 144 (proposed insider sales), 8-K reports (material events such as earnings releases, acquisitions, leadership changes), and periodic reports — the 10-Q (quarterly) and 10-K (annual). All filings are publicly available through SEC EDGAR.

What does a Form 4 filing tell me about WLK?

A Form 4 for WLK discloses a transaction by a company insider — typically a director, officer, or 10%+ shareholder. It shows the source-reported date, number of shares, price, and updated ownership. These facts do not establish motive or predict future returns.

How do I interpret an 8-K filing from Westlake Corporation?

An 8-K signals a material event requiring prompt disclosure. Common triggers include earnings pre-announcements, acquisitions, leadership appointments or departures, credit changes, or regulatory actions. Read the item codes inside the filing to understand exactly what was disclosed before drawing conclusions.

What is the difference between a 10-K and 10-Q for WLK?

The 10-K is Westlake Corporation's annual report with fully audited financial statements, comprehensive MD&A, and complete risk factor disclosures — filed 60–90 days after fiscal year-end. The 10-Q is a lighter quarterly report with unaudited financials filed for the first three quarters. Together they provide a continuous financial picture of the company.

Where can I see all WLK SEC filings directly on EDGAR?

You can view all historical Westlake Corporation filings on the SEC EDGAR company page for WLK. Each filing card on this page links directly to the original SEC document.

How often does Westlake Corporation file with the SEC?

Westlake Corporation files one 10-K per year and up to three 10-Qs per year. Form 4 insider transactions must be reported within two business days of each trade, so the frequency depends on how often insiders are buying or selling WLK shares. 8-K filings occur whenever a material event happens — which can be several times per quarter for an active company.

WLK SEC Filing News — Westlake Corporation

Latest SEC filings for Westlake Corporation (WLK) explained in plain English. Covers insider buying and selling (Form 4), proposed insider sales (Form 144), material company events (8-K), and quarterly & annual reports (10-Q / 10-K). StrongBuyAnalytics provides navigation and brief excerpts or summaries; original filings remain at the SEC/source links and were authored by their filers, not StrongBuyAnalytics. Filing dates shown are source dates. Coverage and detection can be delayed or incomplete because of SEC availability, amendments, parsing, caching, or outages. Latest source filing date shown: 2026-09-29.

Westlake Corporation manufactures and markets performance and essential materials, and housing and infrastructure products in the United States, Canada, Germany, China, Mexico, Brazil, France, Italy, and internationally. It operates through two segments, Performance and Essential Materials and The Housing and Infrastructure Products. The Performance and Essential Materials segment offers ethylene, polyethylene, chlor-alkali, chlorinated derivative products, ethylene dichloride, vinyl chloride mo…

Sector: Basic Materials Industry: Specialty Chemicals Market Cap: $8.0B

Total Filings

Bullish Classifications

Bearish Classifications

Insider Transactions

Material Events (8-K)

Periodic Reports

Rule-based classifications for WLK currently lean bearish. Of the 20 filing records displayed, 1 carry bearish classifications (such as insider sales or negative 8-K disclosures) versus 0 bullish. This does not necessarily signal fundamental deterioration — insiders sell for many reasons — but it is worth monitoring alongside the company's core financial metrics.

WLK Filing Activity Snapshot 2026-08-10 — 2026-09-29

Insider Transactions (Form 4)

0 buys vs 1 sell

Net insider selling in this period — insiders sell for many reasons beyond conviction.

Largest Form 144 Filing

$3.12M

Chao Albert (Director, Executive Chairman) · 2026-08-11

38,873 shares · Form 4

Form 144 Notices

Proposed insider sale filed — Form 144 is a notice of intent, not a confirmed transaction. Actual sales are confirmed via Form 4.

Insider Transactions 17 · Forms 3, 4 and 5

A Form 4 is filed within two business days of a company insider — an officer, a director, or a holder of more than ten percent of the stock — changing their position in the shares. All 17 filings in this group are Form 4s for Westlake Corporation.

The difficulty with reading these filings as a group is that a single form type covers transactions that mean entirely different things. An executive spending their own money to buy stock and an executive having shares withheld to pay tax on a vesting grant both appear as a Form 4. Every filing below is therefore tagged with the nature of the underlying transaction, taken from the transaction code reported on the form itself.

Across the 17 insider filings shown, the breakdown is 11 compensation award, 5 option exercise and 1 open-market sale. 1 of them involved a discretionary open-market trade; the rest are compensation and administrative mechanics.

What each transaction type means

Compensation award ×11: Shares were granted as compensation rather than purchased. No cash changed hands, so the filing reflects a pay decision by the company, not a judgement about the price.
Option exercise ×5: The insider converted options into shares. The exercise price was fixed when the options were granted, so the timing usually tracks an expiry schedule.
Open-market sale ×1: The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Form 4 Compensation award Tax / Compensation Filing 2026-09-01

WLK insider Form 4 filed for equity award, exercise, or tax withholding

Darby Tommy (VP and CAO) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

Shares were granted as compensation rather than purchased. No cash changed hands, so the filing reflects a pay decision by the company, not a judgement about the price.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`A`	Compensation award derivative · Restricted Stock Units	1,791	—	—

Filing: Form 4 (Insider Transaction) Insider: Darby Tommy (VP and CAO)

View on SEC EDGAR → Open Filing Document →

Form 4 Compensation award Tax / Compensation Filing 2026-08-17

WLK insider Form 4 filed for equity award, exercise, or tax withholding

Sheets Jeffrey Wayne (Director) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

Shares were granted as compensation rather than purchased. No cash changed hands, so the filing reflects a pay decision by the company, not a judgement about the price.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`A`	Compensation award derivative · Restricted Stock Units	2,184	—	—

Filing: Form 4 (Insider Transaction) Insider: Sheets Jeffrey Wayne (Director)

View on SEC EDGAR → Open Filing Document →

Form 4 Compensation award Tax / Compensation Filing 2026-08-17

WLK insider Form 4 filed for equity award, exercise, or tax withholding

Sabat Carolyn Chao (Director) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

Shares were granted as compensation rather than purchased. No cash changed hands, so the filing reflects a pay decision by the company, not a judgement about the price.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`A`	Compensation award derivative · Restricted Stock Units	2,184	—	—

Filing: Form 4 (Insider Transaction) Insider: Sabat Carolyn Chao (Director)

View on SEC EDGAR → Open Filing Document →

Form 4 Compensation award Tax / Compensation Filing 2026-08-17

WLK insider Form 4 filed for equity award, exercise, or tax withholding

Patel Bhavesh V. (Director) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

Shares were granted as compensation rather than purchased. No cash changed hands, so the filing reflects a pay decision by the company, not a judgement about the price.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`A`	Compensation award derivative · Restricted Stock Units	2,184	—	—

Filing: Form 4 (Insider Transaction) Insider: Patel Bhavesh V. (Director)

View on SEC EDGAR → Open Filing Document →

Form 4 Compensation award Tax / Compensation Filing 2026-08-17

WLK insider Form 4 filed for equity award, exercise, or tax withholding

NORTHCUTT R BRUCE (Director) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

Shares were granted as compensation rather than purchased. No cash changed hands, so the filing reflects a pay decision by the company, not a judgement about the price.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`A`	Compensation award derivative · Restricted Stock Units	2,184	—	—

Filing: Form 4 (Insider Transaction) Insider: NORTHCUTT R BRUCE (Director)

View on SEC EDGAR → Open Filing Document →

Form 4 Compensation award Tax / Compensation Filing 2026-08-17

WLK insider Form 4 filed for equity award, exercise, or tax withholding

MCCOLLUM MARK A (Director) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

Shares were granted as compensation rather than purchased. No cash changed hands, so the filing reflects a pay decision by the company, not a judgement about the price.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`A`	Compensation award derivative · Restricted Stock Units	2,184	—	—

Filing: Form 4 (Insider Transaction) Insider: MCCOLLUM MARK A (Director)

View on SEC EDGAR → Open Filing Document →

Form 4 Compensation award Tax / Compensation Filing 2026-08-17

WLK insider Form 4 filed for equity award, exercise, or tax withholding

Lubel Kimberly S (Director) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

Shares were granted as compensation rather than purchased. No cash changed hands, so the filing reflects a pay decision by the company, not a judgement about the price.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`A`	Compensation award derivative · Restricted Stock Units	2,184	—	—

Filing: Form 4 (Insider Transaction) Insider: Lubel Kimberly S (Director)

View on SEC EDGAR → Open Filing Document →

Form 4 Compensation award Tax / Compensation Filing 2026-08-17

WLK insider Form 4 filed for equity award, exercise, or tax withholding

Graff Michael J (Director) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

Shares were granted as compensation rather than purchased. No cash changed hands, so the filing reflects a pay decision by the company, not a judgement about the price.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`A`	Compensation award derivative · Restricted Stock Units	2,184	—	—

Filing: Form 4 (Insider Transaction) Insider: Graff Michael J (Director)

View on SEC EDGAR → Open Filing Document →

Form 4 Compensation award Tax / Compensation Filing 2026-08-17

WLK insider Form 4 filed for equity award, exercise, or tax withholding

CREGG ROGER A (Director) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

Shares were granted as compensation rather than purchased. No cash changed hands, so the filing reflects a pay decision by the company, not a judgement about the price.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`A`	Compensation award derivative · Restricted Stock Units	2,184	—	—

Filing: Form 4 (Insider Transaction) Insider: CREGG ROGER A (Director)

View on SEC EDGAR → Open Filing Document →

Form 4 Compensation award Tax / Compensation Filing 2026-08-17

WLK insider Form 4 filed for equity award, exercise, or tax withholding

Chao David Tsung-Hung (Director) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

Shares were granted as compensation rather than purchased. No cash changed hands, so the filing reflects a pay decision by the company, not a judgement about the price.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`A`	Compensation award derivative · Restricted Stock Units	2,184	—	—

Filing: Form 4 (Insider Transaction) Insider: Chao David Tsung-Hung (Director)

View on SEC EDGAR → Open Filing Document →

Form 4 Compensation award Tax / Compensation Filing 2026-08-17

WLK insider Form 4 filed for equity award, exercise, or tax withholding

Chao Catherine T. (Director) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

Shares were granted as compensation rather than purchased. No cash changed hands, so the filing reflects a pay decision by the company, not a judgement about the price.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`A`	Compensation award derivative · Restricted Stock Units	2,184	—	—

Filing: Form 4 (Insider Transaction) Insider: Chao Catherine T. (Director)

View on SEC EDGAR → Open Filing Document →

Form 4 Open-market sale Insider Selling 2026-08-11

WLK insider Chao Albert (Director, Executive Chairman) sold 38,873 shares (~$3.12M)

Chao Albert, listed as Director, Executive Chairman at WESTLAKE CORP, reported an open-market sale of 38,873 WLK shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`M`	Option exercise	38,873	$61.87	$2.40M
`S`	Open-market sale	7,489	$79.70	$596.9K
`S`	Open-market sale	31,384	$80.42	$2.52M
`M`	Option exercise derivative · Employee Option (right to buy)	38,873	—	—

Filing: Form 4 (Insider Transaction) Insider: Chao Albert (Director, Executive Chairman) Shares: 38,873 Est. Value: $3.12M

View on SEC EDGAR → Open Filing Document →

Form 4 Option exercise Tax / Compensation Filing 2026-08-10

WLK insider Form 4 filed for equity award, exercise, or tax withholding

Sheets Jeffrey Wayne (Director) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

The insider converted options into shares. The exercise price was fixed when the options were granted, so the timing usually tracks an expiry schedule.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`M`	Option exercise	2,168	—	—
`M`	Option exercise derivative · Restricted Stock Units	2,168	—	—

Filing: Form 4 (Insider Transaction) Insider: Sheets Jeffrey Wayne (Director) Shares: 2,168

View on SEC EDGAR → Open Filing Document →

Form 4 Option exercise Tax / Compensation Filing 2026-08-10

WLK insider Form 4 filed for equity award, exercise, or tax withholding

Sabat Carolyn Chao (Director) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

The insider converted options into shares. The exercise price was fixed when the options were granted, so the timing usually tracks an expiry schedule.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`M`	Option exercise	2,168	—	—
`M`	Option exercise derivative · Restricted Stock Units	2,168	—	—

Filing: Form 4 (Insider Transaction) Insider: Sabat Carolyn Chao (Director) Shares: 2,168

View on SEC EDGAR → Open Filing Document →

Form 4 Option exercise Tax / Compensation Filing 2026-08-10

WLK insider Form 4 filed for equity award, exercise, or tax withholding

NORTHCUTT R BRUCE (Director) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

The insider converted options into shares. The exercise price was fixed when the options were granted, so the timing usually tracks an expiry schedule.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`M`	Option exercise	2,168	—	—
`M`	Option exercise derivative · Restricted Stock Units	2,168	—	—

Filing: Form 4 (Insider Transaction) Insider: NORTHCUTT R BRUCE (Director) Shares: 2,168

View on SEC EDGAR → Open Filing Document →

Form 4 Option exercise Tax / Compensation Filing 2026-08-10

WLK insider Form 4 filed for equity award, exercise, or tax withholding

MCCOLLUM MARK A (Director) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

The insider converted options into shares. The exercise price was fixed when the options were granted, so the timing usually tracks an expiry schedule.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`M`	Option exercise	2,168	—	—
`M`	Option exercise derivative · Restricted Stock Units	2,168	—	—

Filing: Form 4 (Insider Transaction) Insider: MCCOLLUM MARK A (Director) Shares: 2,168

View on SEC EDGAR → Open Filing Document →

Form 4 Option exercise Tax / Compensation Filing 2026-08-10

WLK insider Form 4 filed for equity award, exercise, or tax withholding

Lubel Kimberly S (Director) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

The insider converted options into shares. The exercise price was fixed when the options were granted, so the timing usually tracks an expiry schedule.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`M`	Option exercise	2,168	—	—
`M`	Option exercise derivative · Restricted Stock Units	2,168	—	—

Filing: Form 4 (Insider Transaction) Insider: Lubel Kimberly S (Director) Shares: 2,168

View on SEC EDGAR → Open Filing Document →

Proposed Insider Sales 1 · Form 144

A Form 144 is a notice of intent to sell restricted or control securities. It is not a record that anything was sold. Westlake Corporation has 1 such notice in this period.

The distinction matters because a Form 144 is frequently reported as though it were a completed insider sale. The filer may sell all of the shares covered, some of them, or none at all, and there is no obligation to update the notice either way. A sale that is actually executed by an officer or director shows up separately on a Form 4, which is the filing to check before treating a proposed sale as a real one.

Form 144 Proposed Insider Sale 2026-08-11

WLK Form 144 filed for proposed insider sale by ALBERT Y CHAO (38,873 shares) ~$3.12M

ALBERT Y CHAO filed a Form 144 with the SEC indicating intent to sell WLK (WESTLAKE CORP) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: ALBERT Y CHAO Shares: 38,873 Est. Value: $3.12M

View on SEC EDGAR → Open Filing Document →

Material Events 2 · Form 8-K

An 8-K reports a material event in the window between scheduled reports. There are 2 in this period for Westlake Corporation. Each 8-K names the item number it is filed under, and that number is the fastest way to tell a routine disclosure from a consequential one.

Item 2.02 is an earnings release, Item 5.02 is a change of directors or officers, and Item 1.01 or 2.01 covers a material agreement or a completed acquisition. Item 7.01 and Item 8.01 are the general-purpose disclosure items and carry no fixed meaning on their own.

Form 8-K Material Company Update 2026-09-29

WLK filed 8-K — material company event

WESTLAKE CORP filed an 8-K with the SEC reporting a material event. Summary unavailable — view the original SEC filing for the full text.

Filing: 8-K (Material Event)

View on SEC EDGAR → Open Filing Document →

Form 8-K Material Company Update 2026-08-31

WLK filed 8-K — material company event

WESTLAKE CORP filed an 8-K with the SEC reporting a material event. Summary unavailable — view the original SEC filing for the full text.

Filing: 8-K (Material Event)

View on SEC EDGAR → Open Filing Document →

How we classify Westlake Corporation's filings

Straight from EDGAR

Each displayed record links to an original source document. StrongBuyAnalytics provides navigation and brief excerpts or summaries, not the filing itself. Parsing may omit context or contain errors, so read the original document in full.

Transaction codes, not guesswork

The nature shown on each insider filing comes from the transaction code the filer entered on the form itself — P for an open-market purchase, A for a compensation award, F for shares withheld to pay tax, M for an option exercise. Where one filing contains several codes, the transaction table lists them line by line.

Why the distinction matters

Insider activity is routinely summarised as buying or selling, which flattens together decisions that mean very different things. Shares withheld for tax on a vesting grant are an automatic administrative step; shares bought on the open market are someone committing their own money at the current price.

What this page does not tell you

A filing records what happened, not why. Form 4 does not always disclose whether a sale was executed under a pre-arranged Rule 10b5-1 plan, and no single filing is a basis for a decision on WLK. Read these alongside the fundamentals rather than in isolation.

Frequently Asked Questions — WLK SEC Filings

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WLK Full Analysis

Publisher, sources & limitations — September 15, 2026. StrongBuyAnalytics provides navigation and brief excerpts or summaries for educational use. Original filings remain at SEC EDGAR or other displayed source links; StrongBuyAnalytics does not author them. Filing dates are source dates, not publication dates for this page. Coverage can be delayed, incomplete, amended, or unavailable because of SEC/source availability, parsing, caching, or outages. Verify every material statement in the original filing.

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