Trinseo (TSE) legal chief has shares withheld to cover RSU taxes

Rhea-AI Filing Summary

Trinseo PLC senior executive reports tax-related share withholding

Trinseo PLC executive Angelo N. Chaclas reported a disposition of 7,607 ordinary shares on February 27, 2026. The transaction was a tax-withholding disposition, where shares were withheld by the company to cover taxes due upon vesting of restricted stock units, rather than an open-market sale. After this transaction, Chaclas held 274,798 ordinary shares directly.

Insider Trade Summary

1 transaction reported

Mixed 1 txn

Insider Chaclas Angelo N.

Role SVP, CLO, CCO & CORP. SEC.

Type	Security	Shares	Price	Value
Tax Withholding	Ordinary Shares	7,607	$0.23	$2K

Holdings After Transaction: Ordinary Shares — 274,798 shares (Direct)

Footnotes (1)

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Form 4 Insider Transactions: What Each Field Means →

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^*

Chaclas Angelo N.

(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, CLO, CCO & CORP. SEC.

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		7,607(1)	D	$0.23	274,798	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 restricted stock units.

	/s/ Angelo Chaclas	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).
** 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.

FAQ

What insider transaction did Trinseo (TSE) report for Angelo N. Chaclas?

Trinseo reported that Angelo N. Chaclas had 7,607 ordinary shares disposed on February 27, 2026. The shares were withheld by the company to pay taxes due when restricted stock units vested, not through an open-market sale.

Was the Trinseo (TSE) insider transaction an open-market sale of shares?

No, the Trinseo insider transaction was not an open-market sale. The 7,607 shares were withheld by the company to satisfy tax liabilities arising from the vesting of restricted stock units awarded to Angelo N. Chaclas.

How many Trinseo (TSE) shares does Angelo N. Chaclas hold after the transaction?

After the tax-withholding disposition, Angelo N. Chaclas directly holds 274,798 Trinseo ordinary shares. This figure reflects his position following the company’s withholding of 7,607 shares to cover tax obligations from vesting restricted stock units.

What does transaction code "F" mean in the Trinseo (TSE) Form 4 filing?

Transaction code "F" indicates a tax-withholding disposition. In this Trinseo filing, it shows the company withheld 7,607 ordinary shares from Angelo N. Chaclas to pay taxes due when his restricted stock units vested.

What role does Angelo N. Chaclas hold at Trinseo (TSE)?

Angelo N. Chaclas serves as Senior Vice President, Chief Legal Officer, Chief Compliance Officer and Corporate Secretary at Trnseo. The reported Form 4 reflects a tax-withholding share disposition tied to his equity compensation vesting.