Trinseo (NYSE: TSE) SVP has 6,064 shares withheld to cover taxes

Rhea-AI Filing Summary

Trinseo PLC reported that SVP of Corporate Finance & IR, Bregje van Kessel, had 6,064 Ordinary Shares withheld on February 27, 2026 to cover taxes due on vesting of previously granted restricted stock units. After this tax-withholding disposition, she directly owned 98,296 Ordinary Shares.

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

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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^*

van Kessel Bregje

(Last) (First) (Middle)

C/O TRINSEO PLC

440 EAST SWEDESFORD ROAD, SUITE 301

(Street)

WAYNE PA 19087

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Trinseo PLC [ TSE ]

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

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	SVP, Corporate Finance & IR

3. Date of Earliest Transaction (Month/Day/Year)
02/27/2026

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

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

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

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
Ordinary Shares	02/27/2026		F		6,064(1)	D	$0.23	98,296	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

Explanation of Responses:

1. Shares withheld by the Company to pay taxes due following the vesting of previously granted restricted stock units.

	/s/ Angelo Chaclas, Attorney-in-Fact	03/03/2026
	** 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).
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FAQ

What insider transaction did Trinseo (TSE) disclose for Bregje van Kessel?

Trinseo disclosed a tax-related share disposition by SVP Bregje van Kessel. On February 27, 2026, 6,064 Ordinary Shares were withheld by the company to pay taxes triggered by vesting of previously granted restricted stock units.

How many Trinseo (TSE) shares were involved in Bregje van Kessel’s Form 4 filing?

The Form 4 shows 6,064 Ordinary Shares involved in the transaction. These shares were not sold on the open market but withheld by Trinseo to satisfy tax obligations upon vesting of restricted stock units.

Was the Trinseo (TSE) Form 4 transaction an open-market sale by Bregje van Kessel?

No, it was not an open-market sale. The filing describes a tax-withholding disposition, where 6,064 shares were retained by Trinseo to cover taxes due when restricted stock units vested.

How many Trinseo (TSE) shares does Bregje van Kessel own after this transaction?

After the tax-withholding transaction, Bregje van Kessel directly owns 98,296 Ordinary Shares of Trinseo. This figure reflects her holdings following the company’s retention of 6,064 shares for tax purposes.

What does transaction code "F" mean in the Trinseo (TSE) insider filing?

Transaction code “F” indicates shares used to pay a tax liability or exercise price. In this case, Trinseo withheld 6,064 shares from Bregje van Kessel to satisfy taxes arising from vesting restricted stock units.

What price per share is reported in Bregje van Kessel’s Trinseo (TSE) Form 4?

The Form 4 reports a price of $0.23 per Ordinary Share for the 6,064 shares withheld. This figure is used to calculate the value of shares applied toward the tax obligation on the vested restricted stock units.