Trinseo (NYSE: TSE) director reports RSU forfeiture and 48,429-share holding

Rhea-AI Filing Summary

Trinseo PLC director Johnson KLynne reported an “other” restructuring transaction involving 42,484 Ordinary Shares at a stated price of $0.00 per share. A footnote explains this reflects a voluntary forfeiture of restricted stock units that had been previously granted and were not yet vested or settled. Following this transaction, Johnson is reported as directly holding 48,429 Ordinary Shares.

Insider Trade Summary

1 transaction reported

Mixed 1 txn

Insider Johnson KLynne

Role null

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

Holdings After Transaction: Ordinary Shares — 48,429 shares (Direct, null)

Footnotes (1)

1. [object Object]

Key Figures

Restructuring transaction shares: 42,484 shares Price per share: $0.00 per share Shares after transaction: 48,429 shares +1 more

4 metrics

Restructuring transaction shares 42,484 shares Code J “other” transaction on Ordinary Shares

Price per share $0.00 per share Stated for the May 12, 2026 transaction

Shares after transaction 48,429 shares Ordinary Shares directly held following the reported event

Restructuring shares total 42,484 shares Classified in summary as restructuringShares

Key Terms

restricted stock units ("RSUs"), voluntary forfeiture, Ordinary Shares, other acquisition or disposition, +1 more

5 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"

Ordinary Shares financial

"security_title": "Ordinary Shares""

Ordinary shares are a type of ownership stake in a company, giving shareholders a right to participate in the company’s profits and decision-making through voting. They are similar to owning a piece of a business, and their value can rise or fall based on the company's performance. Investors buy ordinary shares to potentially earn dividends and benefit from the company's growth over time.

other acquisition or disposition financial

"transaction_code_description": "Other acquisition or disposition""

restructuringShares financial

""restructuringShares": 42484"

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^*

Johnson KLynne

(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)	48,429	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 activity did Trinseo (TSE) disclose for Johnson KLynne?

Trinseo disclosed that director Johnson KLynne reported an “other” restructuring transaction involving 42,484 Ordinary Shares. A related footnote describes this as a voluntary forfeiture of unvested and unsettled restricted stock units rather than a typical open-market buy or sell.

Was the Trinseo (TSE) Form 4 transaction a stock purchase or sale?

The Form 4 does not report a standard purchase or sale. It classifies the May 12, 2026 transaction as code J, an “other acquisition or disposition,” linked to a voluntary forfeiture of unvested restricted stock units at a stated price of $0.00 per share.

How many Trinseo (TSE) shares are reported after Johnson KLynne’s transaction?

After the reported transaction, Johnson KLynne is shown as directly holding 48,429 Ordinary Shares. This figure reflects the position reported on the Form 4 following the restructuring-type event tied to the voluntary forfeiture of restricted stock units.

What does the Trinseo (TSE) Form 4 footnote say about the RSUs?

The footnote states that the transaction reflects a voluntary forfeiture of restricted stock units previously granted on June 25, 2025. It adds that, at the time of forfeiture, this RSU award had not vested or settled, in full or in part, when the restructuring occurred.

What is transaction code J on the Trinseo (TSE) Form 4?

Transaction code J is described as an “other acquisition or disposition” on the Form 4. In this Trinseo filing, it is associated with a restructuring-type event and a voluntary forfeiture of unvested restricted stock units, not a routine open-market trade in Ordinary Shares.