[Form 4] Trinseo PLC Insider Trading Activity

Rhea-AI Filing Summary

Form 4 filing overview: On 06/25/2025, Trinseo PLC (ticker: TSE) disclosed that Director Lynne K. Johnson received 42,484 ordinary shares through a restricted stock unit (RSU) award. The award was booked at an acquisition price of $0 and will vest in full on the first anniversary of the grant date. Following the grant, Johnson’s total beneficial ownership stands at 90,913 ordinary shares. No sales, option exercises, or other derivative transactions were reported, and there were no indications of 10b5-1 plan activity. The transaction is classified under code “A” (grant/acquisition) and is a routine director equity award intended to align management and shareholder interests.

Positive

• Director ownership increased by 42,484 shares, modestly strengthening management–shareholder alignment.

Negative

• None.

Insights

Corporate Governance Expert

TL;DR: Routine RSU grant adds 42k shares to director ownership; modest alignment signal, no immediate valuation impact.

The filing documents a standard annual equity grant rather than an open-market purchase, so cash commitment is absent. Nevertheless, the award increases the director’s stake to roughly 0.12% of Trinseo’s outstanding shares, marginally improving incentive alignment. Because vesting is one year out and no derivative positions were involved, the disclosure carries little short-term valuation weight. I therefore view it as governance-neutral and not materially price-moving.

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^*

Johnson KLynne

(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)
06/25/2025

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	06/25/2025		A		42,484(1)	A	$0	90,913	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. Represents ordinary shares issuable pursuant to a restricted stock unit award that will vest in full on the first anniversary of the grant date.

	/s/ Angelo Chaclas, Attorney-in-Fact	06/27/2025
	** 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

How many Trinseo (TSE) shares did Director Lynne K. Johnson acquire?

42,484 ordinary shares were acquired via an RSU grant.

What is the total number of TSE shares Johnson now beneficially owns?

After the grant, Johnson holds 90,913 shares.

Was any cash paid for the shares in this Form 4 filing?

No. The RSUs were granted at $0 acquisition price.

When will the RSU award reported on 06/25/2025 vest?

The RSUs vest in full one year from the grant date.

Did the Form 4 mention any derivative or option transactions?

No derivative securities were reported in Table II.