[Form 4] Trinseo PLC Insider Trading Activity

Rhea-AI Filing Summary

SEC Form 4 filing overview: On 25 June 2025, Trinseo PLC (ticker: TSE) reported that board director Sandra Beach Lin acquired 42,484 ordinary shares through a restricted stock unit (RSU) grant. The RSUs were issued at a stated price of $0 as part of the company’s equity-based compensation program and will vest in full on the first anniversary of the grant date, according to the single footnote provided.

Post-transaction ownership: Following the award, Lin’s aggregate beneficial ownership increased to 87,260 shares, all held directly.

Materiality assessment: The transaction does not involve open-market buying or selling and therefore does not signal a valuation opinion. It represents standard director compensation and is modest in size relative to Trinseo’s ~35 million shares outstanding (dilution impact well under 0.1%). However, the grant modestly strengthens alignment between the director and shareholders by increasing equity exposure.

Positive

• Enhanced director-shareholder alignment: The 42,484 RSU grant increases the director’s ownership to 87,260 shares, enhancing incentive alignment.

Negative

• Minor potential dilution: New shares will be issued upon vesting, though impact is less than 0.1% of shares outstanding.

Insights

Corporate Governance Expert

TL;DR: Routine director RSU grant; improves alignment, immaterial dilution.

The filing documents a typical annual equity grant to a non-executive director. Because the RSUs vest after one year, they serve as a short-term retention tool and encourage near-term oversight. The grant’s size—42,484 shares—adds roughly 0.12% to the director’s stake but is negligible versus the company’s float, so dilution risk is minimal. No open-market purchase means investors should not read it as a signal on valuation. Overall governance impact is positive but minor.

Portfolio Manager

TL;DR: Neutral for valuation; slight positive for incentive alignment.

From a portfolio perspective, this Form 4 has no immediate earnings or cash-flow implications. The RSU award aligns the director’s interests but doesn’t change the investment thesis, liquidity, or leverage profile. Given Trinseo’s current market cap, the share count effect is immaterial, and the zero-dollar price indicates compensation rather than bullish insider buying. I classify the disclosure as non-impactful for valuation models and trading decisions.

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^*

LIN SANDRA BEACH

(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	87,260	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

What insider transaction did Trinseo (TSE) report?

Director Sandra Beach Lin received 42,484 RSUs on 25 June 2025 as disclosed in a Form 4 filing.

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

Lin now beneficially owns 87,260 ordinary shares.

Was cash paid for the RSUs?

No. The RSUs were granted at a stated price of $0 as part of director compensation.

When will the RSUs vest?

The award vests in full one year after the 25 June 2025 grant date.

Does the Form 4 indicate insider buying or selling?

It indicates a compensation grant, not an open-market purchase or sale.

Is the transaction material for existing shareholders?

Dilution from 42,484 shares is immaterial (well below 0.1%) to Trinseo’s float.