TSE Form 4: Jeanmarie Desmond’s 10,343-Share Tax Withholding

Rhea-AI Filing Summary

Trinseo PLC (Ticker: TSE) – Form 4 filing dated 24 June 2025

The filing discloses an insider transaction by Director Jeanmarie F. Desmond. On 21 June 2025, the company withheld 10,343 ordinary shares to satisfy taxes triggered by the vesting of previously granted restricted stock units, a transaction coded “F” (tax-related disposition). The shares were valued at $3.73 per share. Following the withholding, Desmond’s direct ownership stands at 46,552 ordinary shares.

No derivative securities were reported and there were no open-market purchases or sales. The transaction is administrative in nature and does not represent an active trading decision by the director.

Positive

• None.

Negative

• Director’s share count fell by 10,343 shares (≈18% of prior holdings) through a disposition, modestly lowering insider ownership.

Insights

Securities Analyst

TL;DR: Automatic tax-withholding of 10,343 shares; minimal market signal.

The “F” code indicates a tax-related disposition, not an elective sale. The size—roughly 18% of the director’s pre-transaction holdings—reduces insider ownership but is routine following RSU vesting. No cash proceeds go to the insider, and no derivatives were exercised. Given the small absolute value (≈$38k), the filing is unlikely to influence valuation or liquidity for Trinseo. I classify the impact as neutral.

Corporate Governance Expert

TL;DR: Compliance event; insider still holds 46,552 shares.

Form 4 shows proper Section 16 reporting and Rule 10b5-1 checkbox unchecked, suggesting this was not executed under a pre-arranged plan. The director retains a meaningful equity stake, which maintains alignment with shareholders. No red flags regarding governance or potential conflicts emerge from this routine tax settlement.

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^*

Desmond Jeanmarie F.

(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)

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

3. Date of Earliest Transaction (Month/Day/Year)
06/21/2025

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	06/21/2025		F		10,343(1)	D	$3.73	46,552	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	06/24/2025
	** 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 transaction did Trinseo (TSE) report in this Form 4?

10,343 ordinary shares were withheld from Director Jeanmarie F. Desmond on 21 Jun 2025 to cover taxes on vested RSUs.

Was the insider sale discretionary or automatic?

The filing uses code “F”, indicating an automatic tax-withholding rather than an open-market sale.

What price was assigned to the withheld Trinseo shares?

The shares were valued at $3.73 each for tax-withholding purposes.

How many Trinseo shares does the director own after the transaction?

After the withholding, Jeanmarie F. Desmond owns 46,552 ordinary shares directly.

Does the Form 4 report any derivative securities activity?

No. Table II is blank, indicating no options, warrants, or other derivatives were exercised or disposed.