Westlake director converts 2,168 RSUs into stock

Westlake Corp director Mark A. McCollum reported the vesting and conversion of 2,168 restricted stock units into an equal number of shares of common stock on August 8, 2026.

Rhea-AI Filing Summary

Westlake Corp director Mark A. McCollum reported the vesting and conversion of 2,168 restricted stock units into an equal number of shares of common stock on August 8, 2026. The restricted stock units converted to common stock on a one-for-one basis and were originally granted on August 8, 2025, vesting on the first anniversary of the grant date. Following this transaction, McCollum directly holds 11,824 shares of Westlake common stock.

Insider Trade Summary

2,168 shares exercised/converted

Exercise 2 txns

Insider MCCOLLUM MARK A

Role Director

Type	Security	Shares	Price	Value
Exercise	Restricted Stock Units F1, F2	2,168	$0.00	$0.00
Exercise	Common Stock F1	2,168	--	--

Holdings After Transaction: Restricted Stock Units — 2,168 contracts (Direct); Common Stock — 11,824 shares (Direct)

Footnotes (2)

1. F1. Restricted stock units convert into the Issuer's common stock on a one-for-one basis.
2. F2. On August 8, 2025 the reporting person was granted 2,168 restricted stock units vesting on the first anniversary of the grant date.

Key Figures

Restricted stock units converted: 2,168 units Common shares acquired: 2,168 shares Shares held after transaction: 11,824 shares +1 more

4 metrics

Restricted stock units converted 2,168 units RSUs converted into common stock on August 8, 2026, one-for-one basis

Common shares acquired 2,168 shares Shares of common stock received upon RSU conversion

Shares held after transaction 11,824 shares Direct common stock ownership by Mark A. McCollum following the transactions

RSU grant date August 8, 2025 Grant of 2,168 restricted stock units vesting on first anniversary

Key Terms

Restricted Stock Units, derivative security, vest

3 terms

Restricted Stock Units financial

"Restricted stock units convert into the Issuer's common stock on a one-for-one basis"

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

derivative security financial

"Exercise or conversion of derivative security"

A derivative security is a financial contract whose value comes from the price or performance of something else, such as a stock, bond, commodity, or market index. For investors it acts like an insurance policy or a wager: it can be used to protect against losses, lock in prices, or amplify gains and losses, so it can change a portfolio’s risk and potential return without owning the underlying asset directly.

vest financial

"restricted stock units vesting on the first anniversary of the grant date"

A vest is the process by which an employee earns the right to receive certain benefits or ownership interests, such as stock or retirement funds, over time. It’s similar to earning a reward gradually, ensuring that the benefit becomes fully yours only after a set period or meeting specific conditions. This makes it important for investors because it determines when they can actually claim or use those benefits.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What insider transaction did Westlake Corp (WLK) report for Mark A. McCollum?

Westlake Corp reported that director Mark A. McCollum had 2,168 restricted stock units vest and convert into 2,168 shares of common stock on August 8, 2026, under an equity award originally granted in 2025.

How many Westlake Corp (WLK) shares does Mark A. McCollum hold after this Form 4?

After the reported transactions, Mark A. McCollum directly holds 11,824 shares of Westlake Corp common stock. This reflects the addition of 2,168 shares received from the vesting and conversion of restricted stock units.

What happened to the 2,168 restricted stock units in Westlake Corp (WLK)'s Form 4?

The 2,168 restricted stock units were exercised/converted into 2,168 shares of common stock on August 8, 2026. The derivative position was disposed of as the units converted on a one-for-one basis into common shares.

When were the restricted stock units in Westlake Corp (WLK) originally granted to Mark A. McCollum?

The filing states that on August 8, 2025, Mark A. McCollum was granted 2,168 restricted stock units, which vested on the first anniversary of the grant date, leading to their conversion into common stock in August 2026.

Were the Westlake Corp (WLK) insider transactions under a Rule 10b5-1 plan?

The Form 4 indicates the Rule 10b5-1 checkbox is not affirmed (set to false). The disclosure does not state that these transactions were executed pursuant to a Rule 10b5-1 trading plan.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 08/10/2026 - 01:52 PM EDT Learn about SEC filing dates

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

MCCOLLUM MARK A

(Last) (First) (Middle)

2801 POST OAK BLVD., STE. 600

(Street)

HOUSTON TEXAS 77056

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
WESTLAKE CORP [ WLK ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
08/08/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	08/08/2026		M		2,168	A	(1)	11,824	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Restricted Stock Units	(1)	08/08/2026		M			2,168	(2)	(2)	Common Stock	2,168	$0	2,168	D

Explanation of Responses:

1. Restricted stock units convert into the Issuer's common stock on a one-for-one basis.

2. On August 8, 2025 the reporting person was granted 2,168 restricted stock units vesting on the first anniversary of the grant date.

	Mark McCollum by J Feng POA	08/10/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)