Trinseo (NYSE: TSE) director forfeits 42,484 unvested restricted stock units

Rhea-AI Filing Summary

Trinseo PLC director Henri Steinmetz reported an administrative equity change involving 42,484 shares. The Form 4 shows an "other" transaction in which 42,484 units linked to Ordinary Shares were adjusted at a price of $0.00 per share.

A footnote explains this reflects a voluntary forfeiture of restricted stock units that had been granted earlier and were not yet vested or settled. After this change, Steinmetz is shown as directly holding 53,453 Ordinary Shares, so the filing records a restructuring of unvested awards rather than a market purchase or sale.

Insider Trade Summary

1 transaction reported

Mixed 1 txn

Insider STEINMETZ HENRI

Role null

Type	Security	Shares	Price	Value
Other	Ordinary Shares	42,484	$0.00	--

Holdings After Transaction: Ordinary Shares — 53,453 shares (Direct, null)

Footnotes (1)

1. [object Object]

Key Figures

RSUs forfeited: 42,484 units Price per share: $0.00 per share Shares held after: 53,453 shares

3 metrics

RSUs forfeited 42,484 units Voluntary forfeiture of unvested restricted stock units

Price per share $0.00 per share Stated transaction price for the "other" equity adjustment

Shares held after 53,453 shares Ordinary Shares directly held by Henri Steinmetz after transaction

Key Terms

restricted stock units ("RSUs"), voluntary forfeiture, not vested or settled, transaction code "J"

4 terms

restricted stock units ("RSUs") financial

"Reflects a voluntary forfeiture by the Reporting Person of restricted stock units ("RSUs") that were previously granted"

Restricted stock units (RSUs) are a company promise to give an employee shares of stock (or cash equivalent) in the future, but only after certain conditions—usually staying with the company for a set time or hitting performance goals—are met. Investors watch RSUs because when they vest they increase the number of shares outstanding and can lead insiders to sell shares, affecting share price, company dilution and the true cost of employee pay.

voluntary forfeiture financial

"Reflects a voluntary forfeiture by the Reporting Person of restricted stock units"

not vested or settled financial

"At the time of forfeiture, the RSU award was not vested or settled, in full or in part"

transaction code "J" regulatory

"transaction_code": "J""

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^*

STEINMETZ HENRI

(Last) (First) (Middle)

C/O TRINSEO PLC

440 EAST SWEDESFORD ROAD, SUITE 301

(Street)

WAYNE PENNSYLVANIA 19087

(City) (State) (Zip)

UNITED STATES

(Country)

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)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
05/12/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

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	05/12/2026		J(1)		42,484	D	(1)	53,453	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. Reflects a voluntary forfeiture by the Reporting Person of restricted stock units ("RSUs") that were previously granted on June 25, 2025. At the time of forfeiture, the RSU award was not vested or settled, in full or in part

	/s/ Angelo Chaclas, Attorney-in-Fact	05/14/2026
	** 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.
* Form 4: SEC 1474 (03-26)

FAQ

What insider transaction did Trinseo (TSE) report for Henri Steinmetz?

Trinseo reported an "other" insider transaction for director Henri Steinmetz involving 42,484 Ordinary Shares. A footnote clarifies this reflects a voluntary forfeiture of previously granted, unvested restricted stock units rather than an open-market buy or sell of shares.

How many Trinseo (TSE) shares were affected in Henri Steinmetz’s Form 4?

The Form 4 records 42,484 units linked to Trinseo Ordinary Shares in a transaction coded as "J" (other). According to the footnote, these represented restricted stock units that were voluntarily forfeited and had not yet vested or been settled into actual shares.

Does the Henri Steinmetz Trinseo (TSE) filing show a stock purchase or sale?

The filing does not show a traditional stock purchase or sale. Instead, it reports an "other" transaction in which 42,484 unvested restricted stock units were voluntarily forfeited at a stated price of $0.00 per share, indicating a non-market administrative adjustment.

How many Trinseo (TSE) shares does Henri Steinmetz hold after this transaction?

After the reported transaction, Henri Steinmetz is shown holding 53,453 Trinseo Ordinary Shares directly. This post-transaction holding figure comes from the Form 4 and reflects his remaining direct ownership following the forfeiture of the unvested restricted stock units.

What does the footnote in the Trinseo (TSE) Form 4 for Henri Steinmetz explain?

The footnote explains the entry reflects a voluntary forfeiture of restricted stock units granted on June 25, 2025. It states the RSU award was not vested or settled, in full or in part, clarifying that this was an adjustment to unvested awards rather than trading of existing shares.