[Form 4] Trinseo PLC Insider Trading Activity

Rhea-AI Filing Summary

Roger Greene, VP, Global Controller & PAO of Trinseo PLC (TSE), reported a transaction on 09/25/2025 in which 1,617 ordinary shares were disposed at $2.57 per share. The Form 4 indicates the shares were withheld by the company to pay taxes following the vesting of restricted stock units, and the reporting person now directly beneficially owns 49,856 shares. The filing was signed by an attorney-in-fact on behalf of the reporting person on 09/29/2025. The disclosure is a routine insider tax-withholding event rather than an open-market sale.

Positive

• Transaction disclosed promptly on Form 4 with required details (date, code, amount, price, post-transaction holdings).
• Disposition resulted from tax withholding after RSU vesting, indicating routine compensation administration rather than active selling.

Negative

• None.

Insights

Securities Compliance Analyst

TL;DR: Routine tax-withholding after RSU vesting; small disposition relative to total shares owned, properly reported on Form 4.

The filing shows a Code F disposition where 1,617 shares were withheld to satisfy tax obligations tied to vested restricted stock units. The transaction price is reported at $2.57 per share and leaves the reporting person with 49,856 shares beneficially owned directly. From a compliance perspective, the Form 4 contains the required elements: reporting person identity and role, transaction date, code, amount, price, and remaining ownership. The attorney-in-fact signature is present and dated. There are no indications in this filing of open-market trades or compensation changes beyond standard RSU settlement and withholding.

Corporate Governance Expert

TL;DR: Administrative insider disclosure; immaterial to corporate control or governance dynamics.

The disclosed disposition stems from tax withholding on vested equity rather than a discretionary sale by the insider. The residual direct ownership of 49,856 shares remains, and the filing follows Section 16 reporting rules. This is a routine equity compensation administrative action and does not signal leadership change, control shift, or unusual insider selling pressure based on the information provided.

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
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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).

1. Name and Address of Reporting Person^*

Greene Roger

(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)
	VP, GLOBAL CONTROLLER & PAO

3. Date of Earliest Transaction (Month/Day/Year)
09/25/2025

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	09/25/2025		F		1,617(1)	D	$2.57	49,856	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, Attorney-in-Fact	09/29/2025
	** 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 did Roger Greene report on the Form 4 for Trinseo (TSE)?

He reported a disposition of 1,617 ordinary shares on 09/25/2025 at $2.57 per share, with 49,856 shares beneficially owned afterward.

Why were the 1,617 shares disposed according to the filing?

The filing states the shares were withheld by the company to pay taxes due following the vesting of restricted stock units.

What transaction code was used on the Form 4 and what does it mean?

The transaction was reported with Code F, which here indicates shares were withheld to satisfy tax withholding obligations related to equity vesting.

Who signed the Form 4 and when?

The form was signed by Angelo Chaclas, Attorney-in-Fact on 09/29/2025.

Does this Form 4 indicate an open-market sale by the insider?

No; the filing identifies the disposition as company withholding for taxes after RSU vesting, not a voluntary market sale.