Trinseo (TSE) director Desmond voluntarily forfeits 42,484 unvested RSUs

Rhea-AI Filing Summary

Trinseo PLC director Jeanmarie F. Desmond reported a voluntary forfeiture of equity awards on May 12, 2026. The Form 4 shows an "other" transaction involving 42,484 ordinary shares at a stated price of $0.0000 per share, tied to restricted stock units.

According to the footnote, this reflects a voluntary forfeiture 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, so this is a compensation-related adjustment rather than an open‑market trade. Following the transaction, Desmond directly holds 46,552 ordinary shares.

Insider Trade Summary

1 transaction reported

Mixed 1 txn

Insider Desmond Jeanmarie F.

Role null

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

Holdings After Transaction: Ordinary Shares — 46,552 shares (Direct, null)

Footnotes (1)

1. [object Object]

Key Figures

Restructuring-related shares: 42,484 shares Transaction price: $0.0000 per share Shares after transaction: 46,552 shares +1 more

4 metrics

Restructuring-related shares 42,484 shares Shares tied to voluntary RSU forfeiture coded J

Transaction price $0.0000 per share Stated price for the Form 4 "other" transaction

Shares after transaction 46,552 shares Ordinary shares directly owned following the event

Restructuring shares (summary) 42,484 shares Classified as restructuringShares in transaction summary

Key Terms

restricted stock units ("RSUs"), voluntary forfeiture, Form 4, transaction code "J", +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"

Form 4 regulatory

"INSIDER FILING DATA (Form 4):"

Form 4 is a official document that company insiders, such as executives or major shareholders, file with regulators whenever they buy or sell company shares. It provides transparency about how those with inside knowledge are trading, helping investors see if insiders are confident in the company's prospects or may be selling for personal reasons. This information can influence investor decisions by revealing insiders' perspectives on the company's value.

transaction code "J" regulatory

"transaction_code": "J","transaction_code_description": "Other acquisition or disposition""

other acquisition or disposition regulatory

"transaction_code_description": "Other acquisition or disposition""

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^*

Desmond Jeanmarie F.

(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)	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. 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) director Jeanmarie F. Desmond report?

Jeanmarie F. Desmond reported an "other" transaction on Form 4 involving 42,484 ordinary shares. A footnote explains this reflects a voluntary forfeiture of previously granted restricted stock units that were not vested or settled at the time of forfeiture.

Was the Trinseo (TSE) Form 4 transaction an open-market buy or sell?

No, the Form 4 does not show an open‑market buy or sell. It reports an "other" transaction coded J, tied to a voluntary forfeiture of unvested restricted stock units, with a stated transaction price of zero dollars per share.

How many Trinseo (TSE) shares were affected by the RSU forfeiture?

The Form 4 lists 42,484 ordinary shares associated with the voluntary forfeiture. These relate to restricted stock units that had been granted earlier and were not vested or settled when they were forfeited by the reporting person.

What is Jeanmarie F. Desmond’s Trinseo (TSE) shareholding after this Form 4 event?

After the reported transaction, Jeanmarie F. Desmond directly holds 46,552 ordinary shares of Trinseo PLC. This figure comes from the "shares owned following transaction" field, which reflects her direct ownership position after the RSU forfeiture.

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

The footnote states the transaction reflects a voluntary forfeiture of restricted stock units granted on June 25, 2025. It clarifies that, at the time of forfeiture, the RSU award was not vested or settled, in full or in part.