Form 8-K

8-K — Trinseo PLC

Accession: 0001104659-26-062804

Filed: 2026-05-15

Period: 2026-05-15

CIK: 0001519061

SIC: 2821 (PLASTICS, MATERIALS, SYNTH RESINS & NONVULCAN ELASTOMERS)

Item: Entry into a Material Definitive Agreement

Item: Regulation FD Disclosure

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UNITED STATES

SECURITIES

AND EXCHANGE COMMISSION

Washington,

D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13

or 15(d)

of The Securities Exchange

Act of 1934

Date of Report (Date of earliest event reported):

May 15, 2026

Trinseo

PLC

(Exact name of registrant

as specified in its charter)

Ireland

001-36473

N/A

(State or other jurisdiction

of incorporation or organization)

(Commission

File Number)

(I.R.S. Employer

Identification Number)

440

East Swedesford Road, Suite 301,

Wayne,

Pennsylvania 19087

(Address of principal

executive offices, including zip code)

(610) 240-3200

(Telephone number, including

area code)

Check the appropriate box below if the Form 8-K

filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General

Instruction A.2. below):

¨ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

¨ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

¨ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

¨ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of

the Act:

Title of Each

Class

Trading

symbol(s)

Name of Each Exchange

on which registered

Ordinary Shares, par value $0.01 per share

TSEOF

N/A*

Indicate by check mark whether the registrant

is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2

of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth

company ¨

If an emerging

growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any

new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

* On March 23, 2026, the NYSE filed a Form 25 relating to the delisting

from the NYSE of our ordinary shares. The delisting became effective on March 30, 2026. The ordinary shares will continue to trade over

the counter under the symbol “TSEOF.”

EXPLANATORY NOTE

This Current Report is being filed to report an extension of the expiration

date of the waiver agreement (the “Existing Waiver”) previously disclosed under Item 1.01 of, and filed as an exhibit to,

the Current Report on Form 8-K filed by Trinseo PLC (the “Company”) with the U.S. Securities and Exchange Commission on March

20, 2026 (the “Prior 8-K”). As permitted by the terms of the Existing Waiver, the Company received confirmations from the

counterparties extending the expiration date of the Existing Waiver as described below. No new waiver agreement was entered into in connection

with such extension.

ITEM 1.01 Entry into a Material Definitive Agreement.

Securitization Waiver.

As permitted by the waiver under the Credit and Security Agreement

dated as of July 18, 2024 governing the Company’s accounts receivable securitization facility, the counterparties confirmed the

extension of such waiver’s expiration date until May 27, 2026.

The foregoing description of the Existing Waiver is qualified in its

entirety by reference to the full text of the Existing Waiver, a copy of which was filed as exhibit 10.5 to the Prior 8-K and is incorporated

herein by reference.

ITEM 7.01 Regulation FD Disclosure.

The information set forth in the Explanatory Note and under Item 1.01

of this Current Report on Form 8-K is incorporated by reference into this Item 7.01. The information under this Item 7.01 of this Current

Report on Form 8-K is being furnished and shall not be deemed “filed” for the purpose of Section 18 of the Securities Exchange

Act of 1934, as amended, or otherwise subject to the liabilities of that Section. The information under this Item 7.01 shall not be incorporated

by reference into any registration statement or other document pursuant to the Securities Act of 1933, as amended.

Cautionary Note on Forward Looking Statements

This

Current Report may contain forward-looking statements including, without limitation, statements concerning plans, objectives, goals, projections,

forecasts, strategies, future events or performance, and underlying assumptions and other statements, which are not statements of historical

facts or guarantees or assurances of future performance. Forward-looking statements may be identified by the use of words like “expect,”

“anticipate,” “believe,” “intend,” “forecast,” “outlook,” “will,”

“may,” “might,” “see,” “tend,” “assume,” “potential,” “likely,”

“target,” “plan,” “contemplate,” “seek,” “attempt,” “should,”

“could,” “would” or expressions of similar meaning. Forward-looking statements reflect management’s evaluation

of information currently available and are based on the Company’s current expectations and assumptions regarding its business, the

economy, its current indebtedness, and other future conditions. Because forward-looking statements relate to the future, they are subject

to inherent uncertainties, risks and changes in circumstances that are difficult to predict. Factors that might cause future results to

differ from those expressed by the forward-looking statements include, but are not limited to, outcome of discussions with our financial

stakeholders regarding our capital structure; our ability to obtain necessary waivers, consents or amendments from our lenders; our ability

to consummate the restructuring transactions contemplated by our previously announced Restructuring Support Agreement, obtain Bankruptcy

Court approval of the contemplated Chapter 11 plan of reorganization (the “Plan”) and related financing arrangements

and transactions, satisfy or waive conditions to the effective date of the Plan, including required regulatory approvals and Irish law

implementation steps, and operate our business during the contemplated Chapter 11 process; our ability to successfully execute our overall

business and transformation strategy; increased costs or disruption in the supply of raw materials; deterioration of our credit profile

limiting our access to commercial credit; compliance with laws and regulations impacting our business; conditions in the global economy

and capital markets; our current and future levels of indebtedness and ability to service our debt; our ability to meet the covenants

under our existing indebtedness; our ability to generate cash flows from operations; our ability to successfully implement and complete

proposed restructuring initiatives and to successfully generate cost savings through such initiatives; and those discussed in our Annual

Report on Form 10-K, under Part I, Item 1A — “Risk Factors” and elsewhere in our other reports, filings and furnishings

made with the U.S. Securities and Exchange Commission from time to time. As a result of these or other factors, the Company’s actual

results, performance or achievements may differ materially from those contemplated by the forward-looking statements. Therefore, we caution

you against relying on any of these forward-looking statements. The forward-looking statements included in this Current Report are made

only as of the date hereof. The Company undertakes no obligation to publicly update or revise any forward-looking statement as a result

of new information, future events or otherwise, except as otherwise required by law.

ITEM 9.01

Exhibits.

104

Cover Page Interactive Data File (formatted in Inline XBRL and contained in Exhibit 101)

SIGNATURE

Pursuant to the requirements of the Securities

Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

TRINSEO PLC

By:

/s/ David Stasse

Name:

David Stasse

Title:

Executive Vice President and Chief Financial Officer

Date: May 15, 2026

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