Bregje van Kessel - 21 Feb 2026 Form 4 Insider Report for Trinseo PLC (TSE)

Role: SVP, Corporate Finance & IR
Signature: /s/ Angelo Chaclas, Attorney-in-Fact
Issuer symbol: TSE
Transactions as of: 21 Feb 2026
Net transactions value: -$2,391
Form type: 4
Filing time: 24 Feb 2026, 15:45:43 UTC
Previous filing: 03 Mar 2025
Next filing: 03 Mar 2026
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
van Kessel Bregje	SVP, Corporate Finance & IR	C/O TRINSEO PLC, 440 EAST SWEDESFORD ROAD, SUITE 301, WAYNE	/s/ Angelo Chaclas, Attorney-in-Fact	24 Feb 2026	0001949985

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	TSE	Ordinary Shares	Tax liability	$1,953	-5,963	-5.3%	$0.3276	105,695	21 Feb 2026	Direct	F1
transaction	TSE	Ordinary Shares	Tax liability	$437	-1,335	-1.3%	$0.3276	104,360	22 Feb 2026	Direct	F1

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	Shares withheld by the Company to pay taxes due following the vesting of previously granted restricted stock units.