TSE / Trinseo PLC - Depositi SEC, Relazione annuale, dichiarazione di delega

2 Appliances 2% Mobility 42% Building & Construction3 14% Consumer Electronics 8% MMA 18% Distribution / Other 16% Engineered Materials1 2024 Annual Trinseo Trade Volumes by End Application 1 Percentages are reflected as a % of segment volume (kts) 2

Exhibit 99.1 1 2024 Annual Trinseo Trade Volumes by End Application Building & Construction 3 14% Textile 18% Graphical Paper 25% Board & Specialty Paper 41% Other 2% Latex Binders1 Appliances 11% Mobility 14% Building & Construction 19% Textile Consumer Electronics 5% 3% Packaging 10% Graphical Paper 8% MMA 4% Board & Specialty Paper 12% Distribution / Other 14% Total Company1 2 1 Percentages are

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): August 26, 2025 Trinseo PLC (Exac

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): August 26, 2025 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 Fil

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM S-8 REGISTRATION STATEMENT the SECURITIES ACT OF 1933 Trinseo PLC (Exact Name of Registrant as Specified in Its Charter)

REGISTRATION NO. 333 – UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM S-8 REGISTRATION STATEMENT under the SECURITIES ACT OF 1933 Trinseo PLC (Exact Name of Registrant as Specified in Its Charter) Ireland N/A (State or Other Jurisdiction of Incorporation or Organization) (I.R.S. Employer Identification No.) 440 East Swedesford Road Suite 301 Wayne, PA 19087 (Address,

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2025 ☐TRANSITION REPORT PURS

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2025 or ☐TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-

Calculation of Filing Fee Table

Calculation of Filing Fee Tables S-8 Trinseo PLC Table 1: Newly Registered Securities Security Type Security Class Title Fee Calculation Rule Amount Registered Proposed Maximum Offering Price Per Unit Maximum Aggregate Offering Price Fee Rate Amount of Registration Fee 1 Equity Ordinary Shares, $0.

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): August 6, 2025 Trinseo PLC (Exact

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): August 6, 2025 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

3 Summary Q2 2025 Results • Net loss of $106 million and EPS of negative $2.95 • Adjusted EBITDA* of $42 million, inclusive of $10 million of unfavorable net timing, was $25 million below prior year driven by lower volumes and lower equity income fro

Exhibit 99.2 1 Trademark of Trinseo PLC or its affiliates Second Quarter 2025 Financial Results & Full Year 2025 Outlook August 6, 2025 2 Introductions & Disclosure Rules Introductions • Frank Bozich, President & CEO • David Stasse, Executive Vice President & CFO • Bee van Kessel, Senior Vice President, Corporate Finance & Investor Relations Disclosure Rules This presentation may contain forward-l

Trinseo Reports Second Quarter 2025 Financial Results and Provides 2025 Outlook

Exhibit 99.1 Contact: Bee van Kessel Tel: + 1 835 235 0735 Email: [email protected] Trinseo Reports Second Quarter 2025 Financial Results and Provides 2025 Outlook Second Quarter 2025 Highlights ● Net loss of $106 million and EPS of negative $2.95 ● Adjusted EBITDA* of $42 million, inclusive of $10 million of unfavorable net timing, was $25 million below prior year driven by lower volumes and

Trinseo PLC Amended and Restated 2014 Omnibus Incentive Plan (as amended)

TRINSEO PLC AMENDED AND RESTATED 2014 OMNIBUS INCENTIVE PLAN (as amended February 27, 2025) WHEREAS: A.

Current Report

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): June 25, 2025 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

Conflict Minerals Report as required by Items 1.01 and 1.02 of this Form SD

Exhibit 1.01 TRINSEO PLC Conflict Minerals Report For the Reporting Period from January 1, 2024 to December 31, 2024 This Conflict Minerals Report (the “Report”) of Trinseo PLC (“Trinseo” or the “Company”) for the reporting period from January 1 through December 31, 2024 (“Reporting Period”) is filed as an exhibit to Form SD as provided for in Rule 13p-1 (“Rule”) under the Securities Exchange Act

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM SD Specialized Disclosure Report Trinseo PLC (Exact name of registrant as specified in its charter)

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM SD Specialized Disclosure Report 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

Form of Performance Stock Unit Award Agreement

EXHIBIT 10.2 Name: Target Number of PSUs subject to Vesting and Performance Conditions: Date of Grant: Trinseo PLC Amended & Restated 2014 Omnibus Incentive Plan Performance Award Stock Unit Agreement This agreement (this “Agreement”) evidences an award (the “Award”) of restricted stock units subject to performance conditions (hereinafter referred to as Performance Award Stock Units or “PSUs”) gra

Form of Contingent Restricted Stock Unit Award Agreement

EXHIBIT 10.1 Name: Number of Restricted Stock Units subject to Award: Date of Grant: Trinseo PLC Amended & Restated 2014 Omnibus Incentive Plan Conditional Restricted Stock Unit Agreement This agreement (this “Agreement”) evidences a conditional award (the “Award”) of restricted stock units (the “Restricted Stock Units”) granted by Trinseo PLC (the “Company”) to the undersigned (the “Grantee”) pur

Form of Restricted Cash Unit Award Agreement

EXHIBIT 10.3 Name: Number of Cash Units Awarded: Date of Grant: Trinseo PLC Amended & Restated 2014 Omnibus Incentive Plan Cash Unit Agreement This agreement (this “Agreement”) evidences an award (the “Award”) of cash units (the “Cash Units”) granted by Trinseo PLC (the “Company”) to the undersigned (the “Grantee”) pursuant to the Trinseo PLC Amended and Restated 2014 Omnibus Incentive Plan (as am

Trinseo PLC Insider Trading Policy

EXHIBIT 19.1 Insider Trading Policy The Board of Directors of Trinseo PLC (together with its subsidiaries, the “Company” or “Trinseo”) has adopted this Insider Trading Policy (the “Policy”). This Policy governs the trading by “Insiders” (as defined below) in the securities of the Company, and any other public company as to which the person has become an Insider during the course of his or her empl

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2025 ☐TRANSITION REPORT PUR

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2025 or ☐TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001

Trinseo Reports First Quarter 2025 Financial Results and Provides Second Quarter Outlook

Exhibit 99.1 Contact: Bee van Kessel Tel: +41 44 718 3685 Email: [email protected] Trinseo Reports First Quarter 2025 Financial Results and Provides Second Quarter Outlook First Quarter 2025 Highlights ● Net loss of $79 million and EPS of negative $2.22 included $25 million of refinancing costs for the debt transactions that closed in January 2025 ● Adjusted EBITDA* of $65 million was $20 mil

Current Report

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 7, 2025 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 Nu

3 Summary Q1 2025 Results • Net loss of $79 million and EPS of negative $2.22 included $25 million of refinancing costs for the debt transactions that closed in January 2025 • Adjusted EBITDA* of $65 million was $20 million above prior year driven by

Exhibit 99.2 1 Trademark of Trinseo PLC or its affiliates First Quarter 2025 Financial Results & Second Quarter 2025 Outlook May 7, 2025 2 Introductions & Disclosure Rules Introductions • Frank Bozich, President & CEO • David Stasse, Executive Vice President & CFO • Bee van Kessel, Senior Vice President, Corporate Finance & Investor Relations Disclosure Rules This presentation may contain forward-

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

TABLE OF CONTENTS UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant  ☒ Filed by a Party other than the Registrant  ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ☒ De

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant x Filed by a Party other than the Registrant ¨ Check the appropriate box: ¨ Preliminary Proxy Statement ¨ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ¨ Definitive Proxy State

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

TABLE OF CONTENTS UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant  ☒ Filed by a Party other than the Registrant  ☐ Check the appropriate box: ☒ Preliminary Proxy Statement ☐ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ☐ De

Current Report

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): April 3, 2025 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

Termination of a Material Definitive Agreement

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): March 20, 2025 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 Fil

Subsidiaries of Trinseo PLC

Exhibit 21.1 SUBSIDIARIES OF TRINSEO PLC AS OF DECEMBER 31, 2024 Entity Name Jurisdiction 1. Trinseo Belgium B.V. Belgium 2. Trinseo Operating Belgium B.V. Belgium 3. Trinseo Canada ULC Canada 4. Styron Synthetic Materials (Shanghai) Company Limited China 5. Trinseo Polymers (Zhangjiagang) Company Limited China 6. Altuglas International Denmark A/S Denmark 7. Trinseo Suomi Oy Finland 8. Altuglas I

Description of Securities

Exhibit 4.5 DESCRIPTION OF SECURITIES References to “we”, “us”, “Trinseo” or the “Company” herein are, unless the context otherwise indicates, only to Trinseo PLC and not to any of its subsidiaries. General The following is a summary of information concerning capital stock of Trinseo PLC. The summaries and descriptions below do not purport to be complete statements of the relevant provisions of th

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended: December 31, 2024 ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-36473 Trinseo P

Current Report

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): February 12, 2025 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 F

Trinseo Reports Fourth Quarter 2024 Financial Results and Provides First Quarter 2025 Outlook

Exhibit 99.1 Contact: Bee van Kessel Tel : +41 44 718 3685 Email: [email protected] Trinseo Reports Fourth Quarter 2024 Financial Results and Provides First Quarter 2025 Outlook Fourth Quarter 2024 Highlights ● Cash provided by operations of $85 million and capital expenditures of $21 million resulted in Free Cash Flow* of $64 million, a sequential and year-over-year improvement of $67 millio

3 Summary Q4 2024 Results • Net loss of $118 million and EPS of negative $3.33; included pre-tax restructuring and other charges of $28 million related to the decommissioning of the Stade, Germany polycarbonate plant • Adjusted EBITDA* of $26 million

Exhibit 99.2 1 Trademark of Trinseo PLC or its affiliates Fourth Quarter 2024 Financial Results & First Quarter 2025 Outlook February 12, 2025 2 Introductions & Disclosure Rules Introductions • Frank Bozich, President & CEO • David Stasse, Executive Vice President & CFO • Bee van Kessel, Senior Vice President, Corporate Finance & Investor Relations Disclosure Rules This presentation may contain fo

2025 Incremental Amendment to the Credit Agreement dated September 6, 2017, by and among Trinseo Luxco S.à r.l., Trinseo Holding S.à r.l., Trinseo Materials Finance, Inc., Trinseo Luxco Finance SPV S.à r.l., and Deutsche Bank AG New York Branch, as administrative agent, collateral agent, L/C issuer and swing line lender, and the guarantors and lenders party thereto, dated as of January 17, 2025.

Exhibit 10.2 2025 INCREMENTAL AMENDMENT (this “Amendment”), dated as of January 17, 2025, to the Credit Agreement dated as of September 6, 2017 (as amended, restated, supplemented and/or otherwise modified from time to time prior to the date hereof, the “Existing Credit Agreement”, and the Existing Credit Agreement, as amended by this Amendment, the “Amended Credit Agreement”), by and among TRINSE

Indenture among Trinseo Luxco Finance SPV S.à r.l., Trinseo NA Finance SPV LLC, the guarantors named therein, The Bank of New York Mellon, as trustee, and Alter Domus (US) LLC, as collateral agent, dated as of January 17, 2025 (incorporated by reference to Exhibit 4.2 to the Current Report on Form 8-K filed January 21, 2025).

Exhibit 4.2 TRINSEO LUXCO FINANCE SPV S.À R.L. and TRINSEO NA FINANCE SPV LLC, as Issuers, THE GUARANTORS PARTY HERETO, as Guarantors, THE BANK OF NEW YORK MELLON as Trustee and ALTER DOMUS (US) LLC as Collateral Agent 7.625% Second Lien Senior Secured Notes due 2029 INDENTURE Dated as of January 17, 2025 Table of Contents Page Article I DEFINITIONS AND INCORPORATION BY REFERENCE 1 Section 1.1. De

Entry into a Material Definitive Agreement, Financial Statements and Exhibits

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): January 17, 2025 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 F

Seventh Supplemental Indenture to the indenture dated as of March 24, 2021, by and among Trinseo Holding S.à r.l., Trinseo Materials Finance, Inc., the guarantors named therein, and The Bank of New York Mellon, as trustee, dated as of January 17, 2025.

Exhibit 4.1 SEVENTH SUPPLEMENTAL INDENTURE This SEVENTH SUPPLEMENTAL INDENTURE, (this “Supplemental Indenture”) dated as of January 17, 2025, by and among Trinseo Holding S.à r.l., a private limited liability company (société à responsabilité limitée) organized and existing under the laws of the Grand Duchy of Luxembourg, having its registered office at 26, boulevard Royal, L-2449 Luxembourg, Gran

Third Amendment to Credit Agreement dated as of September 8, 2023, by and among Trinseo NA Finance LLC, Trinseo LuxCo Finance SPV S.à r.l., Trinseo NA Finance SPV LLC, Trinseo PLC, and Alter Domus (US) LLC, as administrative agent and collateral agent, dated January 17, 2025.

Exhibit 10.3 THIRD AMENDMENT TO CREDIT AGREEMENT This THIRD AMENDMENT TO CREDIT AGREEMENT (this “Amendment”) is dated as of January 17, 2025, and is by and among TRINSEO PLC, an Irish public limited company (“Parent”), TRINSEO NA FINANCE LLC, a Delaware limited liability company (“Holdings”), TRINSEO LUXCO FINANCE SPV S.À R.L., a private limited liability company (société à responsabilité limitée)

Credit Agreement, by and among Trinseo Luxco S.à r.l., Trinseo Holding S.à r.l., Trinseo Materials Finance, Inc., Deutsche Bank AG New York Branch, as administrative agent and collateral agent, and the guarantors and lenders party thereto, dated as of January 17, 2025.

Exhibit 10.1 CREDIT AGREEMENT Dated as of January 17, 2025, among TRINSEO LUXCO S.À R.L., as Holdings, TRINSEO HOLDING S.À R.L., as the Lead Borrower, TRINSEO MATERIALS FINANCE, INC., as the Co-Borrower, THE GUARANTORS PARTY HERETO FROM TIME TO TIME, THE LENDERS PARTY HERETO FROM TIME TO TIME and DEUTSCHE BANK AG NEW YORK BRANCH, as Administrative Agent, Collateral Agent, L/C Issuer and Swing Line

Entry into a Material Definitive Agreement, Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant, Other Events

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): January 17, 2025 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 F

Trinseo Announces Expiration and Final Result of the Exchange Offer and Consent Solicitation

Exhibit 99.1 Trinseo Announces Expiration and Final Result of the Exchange Offer and Consent Solicitation WAYNE, PA – January 15, 2025 – Trinseo PLC (NYSE: TSE), a specialty material solutions provider (“Trinseo” or the “Company”), today announced the expiration and final results of the previously announced private exchange offer (the “Exchange Offer”) by Trinseo Luxco Finance SPV S.à r.l. and Tri

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): January 15, 2025 Trinseo PLC (Ex

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): January 15, 2025 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 F

Sixth Supplemental Indenture to the indenture dated as of August 19, 2017, by and among Trinseo Materials Operating S.à r.l., Trinseo Holding S.à r.l., Trinseo Materials Finance, Inc., the Guarantors named therein, and The Bank of New York Mellon, as trustee, dated December 13, 2024.

Exhibit 10.1 SIXTH SUPPLEMENTAL INDENTURE This SIXTH SUPPLEMENTAL INDENTURE, (this “Supplemental Indenture”) dated as of December 13, 2024, by and among Trinseo Materials Operating S.à r.l. (formerly known as Trinseo Materials Operating S.C.A.), a private limited liability company (société à responsabilité limitée) organized and existing under the laws of the Grand Duchy of Luxembourg having its r

2024 LuxCo Merger Amendment, dated as of December 12, 2024, to the Existing Credit Agreement, by and among Trinseo Holding S.à r.l., Trinseo Materials Finance, Inc., Trinseo LuxCo S.à r.l. Deutsche Bank AG New York Branch, as Administrative Agent, dated December 12, 2024.

Exhibit 10.3 Execution Version 2024 LUXCO MERGER AMENDMENT (this “Amendment”), dated as of December 12, 2024, to the Existing Credit Agreement (as hereinafter defined), by and among TRINSEO HOLDING S.À R.L., a private limited liability company (société à responsabilité limitée), organized and established under the laws of the Grand Duchy of Luxembourg, having its registered office at 26, boulevard

Second Amendment to Credit Agreement by and among Trinseo LuxCo S.à.r.l., Trinseo NA Finance LLC, Trinseo LuxCo Finance SPV S.à.r.l., Trinseo NA Finance SPV LLC, Trinseo PLC, and Alter Domus (US) LLC, as Administrative Agent, dated December 12, 2024.

Exhibit 10.4 Execution Version SECOND AMENDMENT TO CREDIT AGREEMENT This SECOND AMENDMENT TO CREDIT AGREEMENT (this “Amendment”) is dated as of December 12, 2024, and is by and among TRINSEO LUXCO S.À R.L., a private limited liability company (société à responsabilité limitée), incorporated and existing under the laws of Luxembourg, having its registered office at 26, boulevard Royal, L-2449 Luxem

Entry into a Material Definitive Agreement, Financial Statements and Exhibits, Other Events

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): December 12, 2024 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

Trinseo Launches Previously Announced Exchange Offer and Consent Solicitation

Exhibit 99.1 Trinseo Launches Previously Announced Exchange Offer and Consent Solicitation WAYNE, PA – December 16, 2024 – Trinseo PLC (NYSE: TSE), a specialty material solutions provider (“Trinseo” or the “Company”), today announced that its subsidiaries, Trinseo Luxco Finance SPV S.à r.l. and Trinseo NA Finance SPV LLC (the “New Issuers”), have commenced a private offer to exchange (the “Exchang

Sixth Supplemental Indenture to the indenture dated as of March 24, 2021, by and among Trinseo Materials Operating S.à r.l., Trinseo Holding S.à r.l., Trinseo Materials Finance, Inc., the Guarantors named therein, and The Bank of New York Mellon, as trustee, dated December 13, 2024.

Exhibit 10.2 SIXTH SUPPLEMENTAL INDENTURE This SIXTH SUPPLEMENTAL INDENTURE, (this “Supplemental Indenture”) dated as of December 13, 2024, by and among Trinseo Materials Operating S.à r.l. (formerly known as Trinseo Materials Operating S.C.A.), a private limited liability company (société à responsabilité limitée) organized and existing under the laws of the Grand Duchy of Luxembourg having its r

TSE / Trinseo PLC / CastleKnight Master Fund LP Passive Investment

SC 13G 1 d11551276.htm UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No.)* Trinseo PLC (Name of Issuer) Common Stock, par value $0.01 per share (Title of Class of Securities) G9059U107 (CUSIP Number) December 10, 2024 (Date of Event Which Requires Filing of this Statement) Check the appropriate box to designa

Transaction Support Agreement, dated December 9, 2024, by and among the Company, and certain of their direct and indirect subsidiaries party thereto, and each of the Supporting Creditors named therein (incorporated by reference to Exhibit 10.1 to the Current Report on Form 8-K filed December 11, 2024).

Exhibit 10.1 CERTAIN INFORMATION HAS BEEN EXCLUDED FROM THIS EXHIBIT BECAUSE IT IS NOT MATERIAL AND IS THE TYPE THAT THE REGISTRANT TREATS AS PRIVATE OR CONFIDENTIAL. THE OMITTED PORTIONS OF THIS DOCUMENT ARE INDICATED BY [***]. Execution Version THIS TRANSACTION SUPPORT AGREEMENT DOES NOT CONSTITUTE, AND SHALL NOT BE DEEMED, AN OFFER TO SELL, OR A SOLICITATION OF AN OFFER TO BUY WITH RESPECT TO A

Entry into a Material Definitive Agreement, Financial Statements and Exhibits

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): December 9, 2024 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 F

Trinseo Enters into Transaction Support Agreement to Extend Debt Maturities and Increase Liquidity

EX-99.1 2 tm2430477d1ex99-1.htm EXHIBIT 99.1 Exhibit 99.1 News Release Trinseo Enters into Transaction Support Agreement to Extend Debt Maturities and Increase Liquidity WAYNE, PA – December 10, 2024 – Trinseo PLC (NYSE: TSE), a specialty material solutions provider, (“Trinseo” or the “Company”) today announced that it and certain of its subsidiaries have entered into a Transaction Support Agreeme

1 Trademark of Trinseo PLC or its affiliates Transaction Support Agreement to Extend Debt Maturities and Increase Liquidity December 10, 2024

EX-99.2 3 tm2430477d1ex99-2.htm EXHIBIT 99.2 Exhibit 99.2 1 Trademark of Trinseo PLC or its affiliates Transaction Support Agreement to Extend Debt Maturities and Increase Liquidity December 10, 2024 2 Disclosure Rules This presentation contains certain forward - looking statements, including without limitation, statements concerning plans, object ives, goals, projections, forecasts, strategies, f

Regulation FD Disclosure, Entry into a Material Definitive Agreement, Financial Statements and Exhibits

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): December 9, 2024 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 Fi

Costs Associated with Exit or Disposal Activities

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K/A Amendment No. 2 CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): September 26, 2024 Trinseo PLC (Exact name of registrant as specified in its charter) Ireland 001-36473 N/A (State or other jurisdiction of incorporation or organiza

TSE / Trinseo PLC / Nut Tree Capital Management, LP - SC 13G Passive Investment

SC 13G 1 ef20038373sc13g.htm SC 13G SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. )* Trinseo PLC (Name of Issuer) Ordinary Shares, par value $0.01 per share (Title of Class of Securities) G9059U107 (CUSIP Number) September 30, 2024 (Date of Event which Requires Filing of this Statement) Check the appropriate box to d

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2024 ☐TRANSITION REPORT

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2024 or ☐TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number:

3 Summary Q3 2024 Results • Net loss of $87 million and EPS of negative $2.47; included pre-tax restructuring and other charges of $26 million related to recently announced restructuring initiatives • Adjusted EBITDA* of $66 million, including a $3 m

Exhibit 99.2 1 Trademark of Trinseo PLC or its affiliates Third Quarter 2024 Financial Results & Fourth Quarter Outlook November 6, 2024 2 Introductions & Disclosure Rules Introductions • Frank Bozich, President & CEO • David Stasse, Executive Vice President & CFO • Bee van Kessel, Senior Vice President, Corporate Finance & Investor Relations Disclosure Rules This presentation may contain forward-

Trinseo Reports Third Quarter 2024 Financial Results and Provides Fourth Quarter Outlook

Exhibit 99.1 Contact: Bee van Kessel Tel : +41 44 718 3685 Email: [email protected] Trinseo Reports Third Quarter 2024 Financial Results and Provides Fourth Quarter Outlook Third Quarter 2024 and Other Highlights ● Net loss of $87 million, including pre-tax restructuring and other charges of $26 million related to recently announced restructuring initiatives, and EPS of negative $2.47 ● Adjus

Current Report

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): November 6, 2024 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 Fi

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K/A Amendment No. 1 CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): September 26, 2024 Trinseo PLC (Exact name of registrant as specified in its charter) Ireland 001-36473 N/A (State or other jurisdiction of incorporation or organiza

Trinseo Announces Additional Restructuring Initiatives Business and support function consolidation as well as exit of virgin polycarbonate production expected to result in $45 million to $50 million of annualized profitability improvement

Exhibit 99.1 News Release Trinseo Announces Additional Restructuring Initiatives Business and support function consolidation as well as exit of virgin polycarbonate production expected to result in $45 million to $50 million of annualized profitability improvement Wayne, Pa, September 30, 2024—Trinseo (NYSE: TSE) (Trinseo or “the Company”), a specialty materials solutions provider, today announced

Current Report

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): September 26, 2024 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

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2024 ☐TRANSITION REPORT PURS

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2024 or ☐TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-

Current Report

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): August 6, 2024 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

3 Summary Q2 2024 Results • Net loss of $68 million and EPS of negative $1.92; included a $13 million non-cash, after-tax charge for an increase in valuation allowance on deferred tax assets in China • Adjusted EBITDA* of $67 million included a $10 m

Exhibit 99.2 1 Trademark of Trinseo PLC or its affiliates Second Quarter 2024 Financial Results & Third Quarter Outlook August 6, 2024 2 Introductions & Disclosure Rules Introductions • Frank Bozich, President & CEO • David Stasse, Executive Vice President & CFO • Andy Myers, Vice President of Investor Relations Disclosure Rules This presentation may contain forward-looking statements including, w

Trinseo Reports Second Quarter 2024 Financial Results and Provides Third Quarter Outlook

Exhibit 99.1 Contact: Andy Myers Tel : +1 610-240-3221 Email: [email protected] Trinseo Reports Second Quarter 2024 Financial Results and Provides Third Quarter Outlook Second Quarter 2024 and Other Highlights ● Net loss of $68 million and EPS of negative $1.92 ● Adjusted EBITDA* of $67 million, including a $10 million unfavorable impact from net timing; Adjusted Net Loss* of $52 million, reflec

Credit and Security Agreement, dated July 18, 2024, among Styron Receivables Funding Designated Activity Company, Trinseo Ireland Global IHB Limited, KKR Credit Advisors (US) LLC, GLAS USA LLC, GLAS Americas LLC, and the Lenders from time to time party thereto.*

EX-10.1 2 tse-20240718xex10d1.htm EX-10.1 Exhibit 10.1 CREDIT AND SECURITY AGREEMENT DATED AS OF July 18, 2024 AMONG Styron receivables funding designated activity company, AS BORROWER, Trinseo Ireland Global IHB Limited, AS THE INVESTMENT MANAGER, THE LENDERS FROM TIME TO TIME PARTY HERETO, GLAS USA LLC, AS ADMINISTRATIVE AGENT, glas americas llc, as collateral agent AND KKR CREDIT ADVISORS (US)

Deed of Release and Termination, dated July 18, 2024, entered into by and among Trinseo Europe GmbH, Trinseo Export GmbH, Trinseo Deutschland Anlagengesellschaft mbH, Trinseo Netherlands B.V., Altuglas LLC, Aristech Surfaces, LLC, Trinseo LLC, Trinseo U.S. Receivables Company SPV LLC, Styron Receivables Funding Designated Activity Company, Regency Assets Designated Activity Company, HSBC Bank plc, Trinseo Holding S.à r.l., TMF Administration Services Limited and the Law Debenture Trust Corporation plc (incorporated by reference to Exhibit 10.2 to the Current Report on Form 8-K filed July 22, 2024).

Exhibit 10.2 daTED ‌18 JULY 2024 (1) TRINSEO EUROPE GMBH (formerly STYRON EUROPE GMBH) (as a Swiss Seller, a Swiss Servicer and Chargor) (2) TRINSEO EXPORT GMBH (as a Swiss Seller, a Swiss Servicer and Pledgor) (3) TRINSEO DEUTSCHLAND ANLAGENGESELLSCHAFT MBH (formerly STYRON DEUTSCHLAND ANLAGENGESELLSCHAFT MBH) (as German Seller and German Servicer) (4) TRINSEO NETHERLANDS B.V. (formerly STYRON NE

Trinseo Announces New Receivables Financing Facility from KKR

Exhibit 99.1 Trinseo Announces New Receivables Financing Facility from KKR WAYNE, Pa. and NEW YORK - July 18, 2024 – Trinseo PLC (“Trinseo” or “the Company”)(NYSE: TSE), a specialty material solutions provider, today announced that a special purpose finance entity, Styron Receivables Funding Designated Activity Company, has entered into a $150 million non-recourse financing facility with credit fu

Entry into a Material Definitive Agreement, Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant

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): July 18, 2024 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

Trinseo Announces Quarterly Dividend of $0.01 Per Share Record Date Correction

Exhibit 99.1 News Release Trinseo Announces Quarterly Dividend of $0.01 Per Share Record Date Correction June 27, 2024 WAYNE, Pa.- Trinseo (NYSE: TSE), a specialty material solutions provider, today announced a correction to its previously issued press release dated June 27, 2024, under the headline “Trinseo Announces Quarterly Dividend of $0.01 Per Share”. The previous press release contained a t

Regulation FD Disclosure

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): June 27, 2024 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

Current Report

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): June 26, 2024 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

Fiscal Year 2020

Trinseo PLC 400 E. Swedesford Rd. Suite 301 Wayne, PA 19087 June 12, 2024 U.S. Securities and Exchange Commission Division of Corporation Finance 100 F Street, NE Washington, DC 20549 Attention: Jeanne Baker Nudrat Salik RE: Trinseo PLC Comment Letter Dated June 7, 2024 Form 10-K for the Year Ended December 31, 2023 File No. 001-36473 To the Staff of the Division of Corporate Finance: Below please

June 5, 2024

Trinseo PLC 400 E. Swedesford Rd. Suite 301 Wayne, PA 19087 June 5, 2024 U.S. Securities and Exchange Commission Division of Corporation Finance 100 F Street, NE Washington, DC 20549 Attention: Jeanne Baker Nudrat Salik RE: Trinseo PLC Comment Letter Dated May 29, 2024 Form 10-K for the Year Ended December 31, 2023 File No. 001-36473 To the Staff of the Division of Corporate Finance: Below please

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2024 ☐TRANSITION REPORT PUR

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2024 or ☐TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001

Form of Performance Award Stock Unit Agreement.

Exhibit 10.4 Name: Target Number of PSUs subject to Vesting and Performance Conditions: Date of Grant: Trinseo PLC Amended & Restated 2014 Omnibus Incentive Plan Performance Award Stock Unit Agreement This agreement (this “Agreement”) evidences an award (the “Award”) of restricted stock units subject to performance conditions (hereinafter referred to as Performance Award Stock Units or “PSUs”) gra

Form of Non-statutory Stock Option Award Agreement.

Exhibit 10.5 Name: Number of Shares of Stock subject to Stock Option: Exercise Price Per Share: Date of Grant: Trinseo PLC Amended & Restated 2014 Omnibus Incentive Plan Non-Statutory Stock Option Agreement This agreement (this “Agreement”) evidences an award (the “Award”) of a stock option (the “Stock Option”) granted by Trinseo PLC (the “Company”) to the undersigned (the “Optionee”) pursuant to

Form of Restricted Stock Unit Award Agreement.

Exhibit 10.3 Name: Number of Restricted Stock Units subject to Award: Date of Grant: Trinseo PLC Amended & Restated 2014 Omnibus Incentive Plan Restricted Stock Unit Agreement This agreement (this “Agreement”) evidences an award (the “Award”) of restricted stock units (the “Restricted Stock Units”) granted by Trinseo PLC (the “Company”) to the undersigned (the “Grantee”) pursuant to the Trinseo PL

Form of Restricted Cash Unit Award Agreement.

Exhibit 10.6 Name: Number of Cash Units Awarded: Date of Grant: Trinseo PLC Amended & Restated 2014 Omnibus Incentive Plan Cash Unit Agreement This agreement (this “Agreement”) evidences an award (the “Award”) of cash units (the “Cash Units”) granted by Trinseo PLC (the “Company”) to the undersigned (the “Grantee”) pursuant to the Trinseo PLC Amended and Restated 2014 Omnibus Incentive Plan (as am

Employment Agreement between Trinseo Netherlands B.V. and Johannes Hendriks, dated August 25, 2022.

Exhibit 10.7 TRINSEO NETHERLANDS B.V. EMPLOYMENT AGREEMENT EMPLOYMENT AGREEMENT (this “Agreement”), dated as of August 5, 2022, is among Trinseo Netherlands B.V., a Dutch limited liability company (Besloten vennootschap met beperkte aansprakelijkheid) (the “Company”), and JOHANNES (also known as “HAN”) LAMBERTUS HENDRIKS (the “Executive”). W I T N E S S E T H WHEREAS, the Company desires to employ

Current Report

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 8, 2024 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 Nu

Trinseo Reports First Quarter 2024 Financial Results and Provides Second Quarter Outlook

Exhibit 99.1 Contact: Andy Myers Tel : +1 610-240-3221 Email: [email protected] Trinseo Reports First Quarter 2024 Financial Results and Provides Second Quarter Outlook First Quarter 2024 and Other Highlights ● Net loss of $76 million and EPS of negative $2.14 ● Adjusted EBITDA* of $45 million, including a $13 million favorable impact from net timing; Adjusted Net Loss* of $69 million ● Cash use

3 Summary Q1 2024 Results • Net loss of $76 million and EPS of negative $2.14 • Adjusted EBITDA* of $45 million included a $13 million favorable impact from net timing • First year-over-year volume increase in two years and highest volumes excluding

Exhibit 99.2 ™ 1 Trademark of Trinseo PLC or its affiliates First Quarter 2024 Financial Results & Second Quarter Outlook May 8, 2024 2 Introductions & Disclosure Rules Introductions • Frank Bozich, President & CEO • David Stasse, Executive Vice President & CFO • Andy Myers, Vice President of Investor Relations Disclosure Rules This presentation may contain forward-looking statements including, wi

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant  ☒ Filed by a Party other than the Registrant  ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ☒ De

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant  ☒ Filed by a Party other than the Registrant  ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ☐ De

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant  ☒ Filed by a Party other than the Registrant  ☐ Check the appropriate box: ☒ Preliminary Proxy Statement ☐ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ☐ De

Entry into a Material Definitive Agreement, Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant

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): March 28, 2024 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

CONTENTS PAGE 1

Exhibit 10.1 daTED ‌28 MARCH 2024 (1) TRINSEO EUROPE GMBH (formerly STYRON EUROPE GMBH) (as a Swiss Seller, a Swiss Servicer and Chargor) (2) TRINSEO EXPORT GMBH (as a Swiss Seller, a Swiss Servicer and Pledgor) (3) TRINSEO DEUTSCHLAND ANLAGENGESELLSCHAFT MBH (formerly STYRON DEUTSCHLAND ANLAGENGESELLSCHAFT MBH) (as German Seller and German Servicer) (4) TRINSEO NETHERLANDS B.V. (formerly STYRON N

Regulation FD Disclosure

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): March 13, 2024 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

Trinseo Announces Commencement of Sale Process for Interest in Americas Styrenics

Exhibit 99.1 News Release Trinseo Announces Commencement of Sale Process for Interest in Americas Styrenics March 13, 2024 WAYNE, Pa.- Trinseo (“Trinseo” or “the Company”) (NYSE: TSE), a specialty material solutions provider, today announced that it has commenced a sale process for its 50% ownership in Americas Styrenics LLC (“AmSty”), a joint venture with Chevron Phillips Chemical Company LP. As

Form of Retention Award Agreement (incorporated by reference to Exhibit 10.1 to the Current Report on Form 8-K filed February 27, 2024).

Trinseo PLC Riverside One, Sir John Rogerson's Quay Dublin 2 D02 X576 Ireland [], 2024 [] Re: Retention Bonus Agreement Dear []: Thank you for your contributions to Trinseo PLC (the “Company”).

Current Report

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): February 21, 2024 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 F

Trinseo PLC Policy for Recoupment of Incentive Compensation

‌Exhibit 97.1 TRINSEO PLC POLICY FOR RECOUPMENT OF INCENTIVE COMPENSATION 1. Introduction In accordance with Section 10D of the Securities Exchange Act of 1934, as amended, and the regulations thereunder, and Section 303A.14 of the New York Stock Exchange Listed Company Manual (the “Listing Standards”), the Compensation Committee of the Board of Directors (the “Board”) of Trinseo PLC (the “Company

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended: December 31, 2023 ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-36473 Trinseo P

Description of Securities

Exhibit 4.3 DESCRIPTION OF SECURITIES References to “we”, “us”, “Trinseo” or the “Company” herein are, unless the context otherwise indicates, only to Trinseo PLC and not to any of its subsidiaries. General The following is a summary of information concerning capital stock of Trinseo PLC. The summaries and descriptions below do not purport to be complete statements of the relevant provisions of th

Subsidiaries of Trinseo PLC

Exhibit 21.1 SUBSIDIARIES OF TRINSEO PLC AS OF DECEMBER 31, 2023 Entity Name Jurisdiction 1. Trinseo Belgium B.V. Belgium 2. Trinseo Operating Belgium B.V. Belgium 3. Trinseo Canada ULC Canada 4. Styron Synthetic Materials (Shanghai) Company Limited China 5. Trinseo Polymers (Zhangjiagang) Company Limited China 6. Altuglas International Denmark A/S Denmark 7. Trinseo Suomi Oy Finland 8. Altuglas I

Deed of Amendment and Restatement and Waiver dated November 23, 2023, entered into by and among Trinseo Europe GmbH, Trinseo Export GmbH, Trinseo Deutschland Anlagengesellschaft mbH, Trinseo Netherlands B.V., Trinseo LLC, Trinseo U.S. Receivables Company SPV LLC, Styron Receivables Funding Designated Activity Company, Trinseo Ireland Global IHB Limited, Regency Assets Designated Activity Company, HSBC Bank plc, Trinseo Holding S.à r.l., TMF Administration Services Limited and the Law Debenture Trust Corporation plc

Exhibit 10.10 EXECUTION VERSION DATED 23 NOVEMBER 2023 TRINSEO EUROPE GMBH (formerly STYRON EUROPE GMBH) (as a Swiss Seller, a Swiss Servicer and Chargor) TRINSEO EXPORT GMBH (as a Swiss Seller, a Swiss Servicer and Pledgor) TRINSEO DEUTSCHLAND ANLAGENGESELLSCHAFT MBH (formerly STYRON DEUTSCHLAND ANLAGENGESELLSCHAFT MBH) (as German Seller and German Servicer) TRINSEO NETHERLANDS B.V. (formerly STY

First Amendment to Credit Agreement, dated January 26, 2024, to the Credit Agreement dated as of September 8, 2023 among Trinseo Luxco SARL, Trinseo NA Finance LLC, Trinseo Luxco Finance SPV SARL, Trinseo NA Finance SPV LLC, the guarantors party thereto from time to time, the lenders party thereto from time to time and Alter Domus (US) LLC, as administrative agent and collateral agent.

Exhibit 10.8 Execution Version FIRST AMENDMENT TO CREDIT AGREEMENT This FIRST AMENDMENT TO CREDIT AGREEMENT (this “Amendment”) is dated as of January 26, 2024, and is by and among TRINSEO LUXCO S.À R.L., a private limited liability company (société à responsabilité limitée), incorporated and existing under the laws of Luxembourg, having its registered office at 26, boulevard Royal, L-2449 Luxembou

Trinseo PLC Insider Trading Policy

Exhibit 19.1 TRINSEO PLC INSIDER TRADING POLICY The Board of Directors of Trinseo PLC (together with its subsidiaries, the “Company” or “Trinseo”) has adopted this Insider Trading Policy (the “Policy”). This Policy governs the trading by “Insiders” (as defined below) in the securities of the Company, and any other public company as to which the person has become an Insider during the course of his

Trinseo Reports Fourth Quarter and Full-Year 2023 Financial Results; Provides First Quarter 2024 Outlook

Exhibit 99.1 Contact: Andy Myers Tel : +1 610-240-3221 Email: [email protected] Trinseo Reports Fourth Quarter and Full-Year 2023 Financial Results; Provides First Quarter 2024 Outlook Full-Year 2023 Summary ● Cash from operations of $149 million and capital expenditures of $70 million resulted in Free Cash Flow* of $79 million; and a $47 million year-over-year increase to $259 million cash at y

3 Summary Q4 2023 Results • Net loss from continuing operations of $265 million included a pre-tax charge of approximately $38 million related to restructuring initiatives and non-cash after-tax charges of approximately $160 million related to increa

Exhibit 99.2 ™Trademark of Trinseo PLC or its affiliates 1 Fourth Quarter 2023 Financial Results & First Quarter 2024 Outlook February 12, 2024 2 Introductions & Disclosure Rules Introductions • Frank Bozich, President & CEO • David Stasse, Executive Vice President & CFO • Andy Myers, Director of Investor Relations Disclosure Rules This presentation may contain forward-looking statements including

Current Report

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): February 12, 2024 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 F

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2023 ☐TRANSITION REPORT

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2023 or ☐TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number:

3 Summary Q3 2023 Results • Net loss from continuing operations of $38 million and Adjusted EBITDA* of $41 million; net loss included a $14 million charge related to the Company’s PMMA sheet optimization and Corporate restructuring initiatives • Adju

Exhibit 99.2 ™Trademark of Trinseo PLC or its affiliates 1 Third Quarter 2023 Financial Results & Full-Year Outlook November 3, 2023 2 Introductions & Disclosure Rules Introductions • Frank Bozich, President & CEO • David Stasse, Executive Vice President & CFO • Andy Myers, Director of Investor Relations Disclosure Rules This press release may contain forward-looking statements including, without

Trinseo Reports Third Quarter 2023 Financial Results and Updates 2023 Outlook

Exhibit 99.1 Contact: Andy Myers Tel : +1 610-240-3221 Email: [email protected] Trinseo Reports Third Quarter 2023 Financial Results and Updates 2023 Outlook Third Quarter 2023 and Other Highlights ● Cash provided by operations of $29 million and capital expenditures of $13 million resulted in Free Cash Flow* of $16 million including a $52 million decrease in working capital ● Third quarter endi

Current Report

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): November 3, 2023 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 Fi

Trinseo Completes Strategic Network Optimization Initiative with Closure of Terneuzen, the Netherlands Styrene Manufacturing Operations.

Exhibit 99.1 Trinseo Completes Strategic Network Optimization Initiative with Closure of Terneuzen, the Netherlands Styrene Manufacturing Operations. -Closure effective November 1, 2023 -Follows previously announced closures of PMMA sheets operations in Bronderslev, Denmark, Belen, New Mexico and extruded sheets line in Rho, Italy -Supports continued transformation of the company’s portfolio to fo

Costs Associated with Exit or Disposal Activities

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K/A Amendment No. 1 CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): October 26, 2023 (August 17, 2023) Trinseo PLC (Exact name of registrant as specified in its charter) Ireland 001-36473 N/A (State or other jurisdiction of incorpora

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): September 21, 2023 Trinseo PLC (E

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): September 21, 2023 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

2023 Incremental and Refinancing Amendment, dated as of September 8, 2023, among Trinseo Holding SARL, Trinseo Ireland Holdings Limited, Trinseo Materials Operating S.C.A., Trinseo Materials Finance, Inc. the guarantors party thereto from time to time, the lenders party thereto from time to time and Deutsche Bank AG New York Branch, as administrative agent and collateral agent.

Exhibit 10.2 Execution Version 2023 INCREMENTAL AND REFINANCING AMENDMENT (this “Amendment”), dated as of September 8, 2023, to the Credit Agreement dated as of September 6, 2017 (as amended, restated, supplemented and/or otherwise modified from time to time prior to the date hereof, the “Existing Credit Agreement”, and the Existing Credit Agreement, as amended by this Amendment, the “Amended Cred

Trinseo Announces Completion of Transaction to Refinance $660 million 2024 Term Loan and $385 million of 2025 Senior Notes

Exhibit 99.1 Trinseo Announces Completion of Transaction to Refinance $660 million 2024 Term Loan and $385 million of 2025 Senior Notes September 8, 2023 WAYNE, Pa.- Trinseo (“Trinseo” or “the Company”) (NYSE: TSE), a specialty material solutions provider, today announced that it has obtained $1.077 billion in aggregate principal amount of secured term loan financing (“New Term Loan Facility”) arr

Credit Agreement, dated as of September 8, 2023, among Trinseo Luxco SARL, Trinseo NA Finance LLC, Trinseo Luxco Finance SPV SARL, Trinseo NA Finance SPV LLC, the guarantors party thereto from time to time, the lenders party thereto from time to time and Alter Domus (US) LLC, as administrative agent and collateral agent (incorporated by reference to Exhibit 10.1 to the Current Report on Form 8-K filed on September 8, 2023)

Exhibit 10.1 CREDIT AGREEMENT Dated as of September 8, 2023, among TRINSEO LUXCO S.À R.L., as Parent, Trinseo NA Finance LLC, as Holdings, TRINSEO LUXCO FINANCE SPV S.À R.L., as the Lead Borrower, Trinseo NA Finance SPV LLC, as the Co-Borrower, THE GUARANTORS PARTY HERETO FROM TIME TO TIME, THE LENDERS PARTY HERETO FROM TIME TO TIME, and ALTER DOMUS (US) LLC, as Administrative Agent and Collateral

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): September 8, 2023 Trinseo PLC (Ex

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): September 8, 2023 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 F

Current Report

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): August 17, 2023 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 Fil

2 Cash Generation Forecast • Cash Interest and Cash Taxes assume the capital structure as of June 30, 2023 • 2024 Restructuring costs primarily related to the Boehlen, Germany styrene closure (~$25 million) and the potential Terneuzen, the Netherland

Exhibit 99.1 1 2023 to 2024 Profitability Bridge (In $millions, unless noted) Low Base High 2023 Net Income (Loss) from Continuing Operations (460) (460) (460) 2023 Adjusted EBITDA* 215 215 215 Net Timing 18 18 18 Volume 0 80 110 Potential Terneuzen Closure 55 55 55 Natural Gas Hedge Losses 35 35 35 Other 3 12 14 2024 Adjusted EBITDA* 326 415 447 2024 Net Income (Loss) from Continuing Operations (

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): August 16, 2023 Trinseo PLC (Exac

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): August 16, 2023 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 Fil

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): August 9, 2023 Trinseo PLC (Exact

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): August 9, 2023 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

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2023 ☐TRANSITION REPORT PURS

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2023 or ☐TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-

Calculation of Filing Fee Table

Exhibit 107 Calculation of Filing Fee Tables Form S-8 (Form Type) Trinseo PLC (Exact Name of Registrant as Specified in its Charter) Table 1: Newly Registered Securities Security Type Security Class Title Fee Calculation Rule Amount Registered Proposed Maximum Offering Price Per Share Maximum Aggregate Offering Price(2) Fee Rate Amount of Registration Fee(2) Equity Ordinary Shares, $0.

2023 SOFR Amendment to the Credit Agreement dated September 6, 2017 among Trinseo Materials Operating S.C.A., Trinseo Materials Finance, Inc., together with Trinseo Holding S.à r.l. and Trinseo Ireland Holdings Limited, Deutsche Bank AG New York Branch, as administrative agent, collateral agent, L/C issuer and swing line lender, and the guarantors and lenders party thereto from time to time, dated as of June 30, 2023 (incorporated by reference to Exhibit 10.2 to the Quarterly Report on Form 10-Q for the quarter ended June 30, 2023, filed on August 4, 2023)

POSTING VERSION Exhibit 10.2 2023 SOFR AMENDMENT (this “Amendment”), dated as of June 30, 2023, to the Credit Agreement dated as of September 6, 2017 (as amended, restated, supplemented and/or otherwise modified from time to time prior to the date hereof, the “Existing Credit Agreement”, and the Existing Credit Agreement, as amended by this Amendment, the “Amended Credit Agreement”) among TRINSEO

As filed with the Securities and Exchange Commission on August 4, 2023

As filed with the Securities and Exchange Commission on August 4, 2023 REGISTRATION NO.

3 Summary Q2 2023 Results • Net loss from continuing operations of $349 million and Adjusted EBITDA* of $57 million; net loss included a non-cash goodwill impairment of $349 million • Results included pre-tax impacts of $16 million for unfavorable ne

Exhibit 99.2 ™Trademark of Trinseo PLC or its affiliates 1 Second Quarter 2023 Financial Results & Full-Year Outlook August 3, 2023 2 Introductions & Disclosure Rules Introductions • Frank Bozich, President & CEO • David Stasse, Executive Vice President & CFO • Andy Myers, Director of Investor Relations Disclosure Rules This press release may contain forward-looking statements including, without l

Current Report

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): August 3, 2023 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

Trinseo Reports Second Quarter 2023 Financial Results, Announces Additional Restructuring Initiatives and Updates 2023 Outlook

Exhibit 99.1 Contact: Andy Myers Tel : +1 610-240-3221 Email: [email protected] Trinseo Reports Second Quarter 2023 Financial Results, Announces Additional Restructuring Initiatives and Updates 2023 Outlook Second Quarter 2023 ● Net loss from continuing operations of $349 million and diluted EPS from continuing operations of negative $9.93 ● Net loss includes a pre-tax, non-cash goodwill impairm

Current Report

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): July 20, 2023 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

Trinseo Announces Executive Leadership Team Changes

Trinseo Announces Executive Leadership Team Changes - Trinseo is restructuring its Executive Leadership Team (ELT) in a move specifically designed to create a more streamlined organizational structure that will help drive improved performance, value creation, and delivery of Trinseo’s transformation strategy.

Separation Agreement with Andre Lanning dated July 18, 2023

Trinseo Europe GmbH Gwattstrasse 15 8808 Pfäffikon (SZ), Switzerland Personal and Confidential Delivered Via Email Pfäffikon, 17 July 2023 Separation Agreement Dear André, We would like to summarize the mutually agreed to details concerning your resignation and separation from Trinseo Europe GmbH on 31 January 2024, unless otherwise adjusted as described below.

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): July 20, 2023 Trinseo PLC (Exact

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): July 20, 2023 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

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): June 14, 2023 Trinseo PLC (Exact

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): June 14, 2023 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

Trinseo PLC Amended and Restated 2014 Omnibus Incentive Plan (as amended)

Exhibit 10.1 TRINSEO PLC AMENDED AND RESTATED 2014 OMNIBUS INCENTIVE PLAN (as amended June 14, 2023) WHEREAS: A.On May 30, 2014, Trinseo S.A., a public limited company (société anonyme) incorporated under the laws of Luxembourg, adopted the Trinseo S.A. 2014 Omnibus Incentive Plan (as so adopted and amended, from time to time, in respect of periods prior to the Effective Time (as defined below), t

  UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

      UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549   SCHEDULE 14A   Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934   Filed by the Registrant   x   Filed by a Party other than the Registrant   ¨   Check the appropriate box:   ¨ Preliminary Proxy Statement   ¨ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant  x Filed by a Party other than the Registrant  ¨ Check the appropriate box: ¨ Preliminary Proxy Statement ¨ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ¨ Definitive Proxy Sta

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2023 ☐TRANSITION REPORT PUR

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2023 or ☐TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001

Employment Agreement between Trinseo LLC and Paula Cooney, dated October 15, 2021 (incorporated by reference to Exhibit 10.1 to the Quarterly Report on Form 10-Q for the quarter ended March 31, 2023 filed May 5, 2023)

Exhibit 10.1 TRINSEO LLC EMPLOYMENT AGREEMENT EMPLOYMENT AGREEMENT (this “Agreement”), dated as of October 15, 2021 (the “Effective Date”), among Trinseo LLC, a Delaware limited liability company, with offices at 1000 Chesterbrook Boulevard, Suite 300, Berwyn, Pennsylvania 19312 (the “Company”), and Paula Cooney, of 100 S. 3rd Avenue, Unit 1503, Minneapolis, MN 55401 (the “Executive”). W I T N E S

Deed of Amendment and Restatement, dated March 31, 2023, entered into by and among Trinseo Europe GmbH, Trinseo Export GmbH, Trinseo Deutschland Anlagengesellschaft mbH, Trinseo Netherlands B.V., Trinseo LLC, Trinseo U.S. Receivables Company SPV LLC, Styron Receivables Funding Designated Activity Company, Trinseo Finance Luxembourg S.à r.l., Luxembourg, Zweigniederlassung Horgen, Regency Assets Designated Activity Company, HSBC Bank plc, Trinseo Holding S.à r.l., TMF Administration Services Limited and the Law Debenture Trust Corporation plc.

Exhibit 10.3 DATED 31 MARCH 2023 TRINSEO EUROPE GMBH (formerly STYRON EUROPE GMBH) (as a Swiss Seller, a Swiss Servicer and Chargor) TRINSEO EXPORT GMBH (as a Swiss Seller, a Swiss Servicer and Pledgor) TRINSEO DEUTSCHLAND ANLAGENGESELLSCHAFT MBH (formerly STYRON DEUTSCHLAND ANLAGENGESELLSCHAFT MBH) (as German Seller and German Servicer) TRINSEO NETHERLANDS B.V. (formerly STYRON NETHERLANDS B.V.)

Regulation FD Disclosure

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 5, 2023 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 Nu

Amendment, dated May 9, 2022, to the Employment Agreement between Trinseo LLC and Paula Cooney dated October 15, 2021 (incorporated by reference to Exhibit 10.2 to the Quarterly Report on Form 10-Q for the quarter ended March 31, 2023 filed May 5, 2023)

Exhibit 10.2 Trinseo PLC 76 Sir John Rogerson’s Quay Dublin 2 D02 FX51, Ireland Paula Cooney May 9, 2022 S.V.P., Chief Human Resources Officer Dear Paula, We are pleased to confirm a change in your Change of Control benefit under your employment contract with Trinseo PLC or its affiliate. Basically, the change increases the severance amount from 18 months to 24 months provided all other conditions

Trinseo Reports First Quarter 2023 Financial Results, Announces Cash Improvement Initiatives and Updates 2023 Outlook

Exhibit 99.1 Contact: Andy Myers Tel : +1 610-240-3221 Email: [email protected] Trinseo Reports First Quarter 2023 Financial Results, Announces Cash Improvement Initiatives and Updates 2023 Outlook First Quarter 2023 and Other Highlights ● Net loss from continuing operations of $49 million and diluted EPS from continuing operations of negative $1.40 ● Adjusted EBITDA* of $36 million, including a

Summary 2023 Outlook Q1 2023 Results • Q1 cash provided by operations of $45 million led to Free Cash Flow* of $24 million – included a working capital release of $52 million from inventory reduction • Q1 ending cash balance of $217 million with $251

Exhibit 99.2 ™Trademark of Trinseo PLC or its affiliates First Quarter 2023 Financial Results & Full-Year Outlook May 4, 2023 2 Introductions & Disclosure Rules Disclosure Rules This press release may contain forward-looking statements including, without limitation, statements concerning plans, objectives, goals, projections, forecasts, strategies, future events or performance, and underlying assu

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 4, 2023 Trinseo PLC (Exact na

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 4, 2023 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 Nu

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant x Filed by a Party other than the Registrant ¨ Check the appropriate box: ¨ Preliminary Proxy Statement ¨ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ¨ Definitive Proxy State

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

TABLE OF CONTENTS UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant  ☒ Filed by a Party other than the Registrant  ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ☒ De

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

TABLE OF CONTENTS UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant  ☒ Filed by a Party other than the Registrant  ☐ Check the appropriate box: ☒ Preliminary Proxy Statement ☐ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ☐ De

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): April 13, 2023 Trinseo PLC (Exact

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): April 13, 2023 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

Description of Securities

EX-4.3 2 tse-20221231xex4d3.htm EX-4.3 Exhibit 4.3 DESCRIPTION OF SECURITIES References to “we”, “us”, “Trinseo” or the “Company” herein are, unless the context otherwise indicates, only to Trinseo PLC and not to any of its subsidiaries. General The following is a summary of information concerning capital stock of Trinseo PLC. The summaries and descriptions below do not purport to be complete stat

Form of Restricted Stock Unit Agreement for Directors (incorporated herein by reference to Exhibit 10.33 to the Company’s Annual Report on Form 10-K for the year ended December 31, 2022, filed on February 27, 2023)

Exhibit 10.33 Name: /$ParticipantName$/ Number of Restricted Stock Units subject to Award: /$AwardsGranted$/ Date of Grant: /$GrantDate$/ TRINSEO PLC Non-Employee Equity Incentive Plan (sub-plan of the Amended& Restated 2014 Omnibus Incentive Plan) Restricted Stock Unit Agreement (Non-Employee Directors) This agreement (this “Agreement”) evidences an award (the “Award”) of restricted stock units (

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended: December 31, 2022 ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-36473 Trinseo P

Subsidiaries of Trinseo PLC

Exhibit 21.1 SUBSIDIARIES OF TRINSEO PLC AS OF DECEMBER 31, 2022 Entity Name Jurisdiction 1. Trinseo Belgium B.V. Belgium 2. Trinseo Operating Belgium B.V. Belgium 3. Trinseo Canada ULC Canada 4. Styron Synthetic Materials (Shanghai) Company Limited China 5. Trinseo Polymers (Zhangjiagang) Company Limited China 6. Altuglas International Denmark A/S Denmark 7. Trinseo Suomi Oy Finland 8. Altuglas I

Summary 2023 Outlook Q4 2022 Results • Q4 cash provided by operations of $34 million led to Free Cash Flow* of negative $20 million - included working capital release of $88 million and $34 million payment for European Commission settlement • 2022 en

Exhibit 99.2 ™Trademark of Trinseo PLC or its affiliates Fourth Quarter 2022 Financial Results & 2023 Outlook February 8, 2023 2 Introductions & Disclosure Rules Disclosure Rules Cautionary Note on Forward-Looking Statements.This presentation may contain forward-looking statements including, without limitation, statements concerning plans, objectives, goals, projections, forecasts, strategies, fut

Trinseo Reports Fourth Quarter and Full-Year 2022 Financial Results; Provides Full-Year 2023 Guidance

Exhibit 99.1 Contact: Andy Myers Tel : +1 610-240-3221 Email: [email protected] Trinseo Reports Fourth Quarter and Full-Year 2022 Financial Results; Provides Full-Year 2023 Guidance Full-Year 2022 Summary ● Net loss from continuing operations of $428 million and diluted EPS from continuing operations of negative $11.91 ● Adjusted EBITDA* of $312 million, including a $21 million favorable impact

Current Report

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): Februrary 8, 2023 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 F

Current Report

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): January 26, 2023 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 Fi

Trinseo Announces Fourth Quarter and Full-Year 2022 Expected Results and Goodwill Impairment; Provides Details for Fourth Quarter 2022 Conference Call

Exhibit 99.1 Contact: Trinseo Andy Myers Tel : +1 610-240-3221 Email: [email protected] Trinseo Announces Fourth Quarter and Full-Year 2022 Expected Results and Goodwill Impairment; Provides Details for Fourth Quarter 2022 Conference Call Fourth Quarter 2022 Expected Results ● Net loss from continuing operations of $367 million to $362 million and Adjusted EBITDA* of $4 million to $9 million ● N

TSE / Trinseo S.A. / BlackRock Inc. Passive Investment

SC 13G/A 1 ie0000qbk8u7012323.txt ie0000qbk8u7012323.txt SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No: 2) TRINSEO PLC - (Name of Issuer) Common Stock - (Title of Class of Securities) BP48297 - (SEDOL Number) December 31, 2022 - (Date of Event Which Requires Filing of this Statement) Check the appropriate box to desig

Current Report

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): December 13, 2022 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 F

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2022 ☐TRANSITION REPORT

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 ? ? FORM 10-Q ? ? ? (Mark One) ?QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2022 or ?TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission Fi

Summary 2022 Outlook Q3 2022 Results•Q3 cash provided by operations of $98 million led to Free Cash Flow* of $59 million•Working capital release of $166 million attributed mostly to a sharp decline in raw material costs•Q3 ending cash of $243 million

Exhibit 99.2 ?Trademark of Trinseo PLC or its affiliates Third Quarter 2022 Financial Results & Full-Year 2022 OutlookNovember 2, 2022 2 Introductions & Disclosure RulesDisclosure RulesCautionary Note on Forward-Looking Statements.This presentation may contain forward-looking statements including, without limitation, statements concerning plans, objectives, goals, projections, forecasts, strategie

Current Report

? ? 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): November 2, 2022 ? Trinseo PLC (Exact name of registrant as specified in its charter) ? ? ? ? ? ? Ireland ? 001-36473 ? N/A (State or other jurisdiction of incorporation or

Trinseo Reports Third Quarter 2022 Financial Results; Updates Full-Year Outlook

Exhibit 99.1 ? ? ? ? ? Contact: Trinseo Andy Myers Tel : +1 610-240-3221 Email: [email protected] ? Trinseo Reports Third Quarter 2022 Financial Results; Updates Full-Year Outlook ? Third Quarter 2022 and Other Highlights ? ? Net loss from continuing operations of $118 million and diluted EPS from continuing operations of negative $3.35 ? Adjusted EBITDA* of negative $37 million, including a $24

Current Report

? ? 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): October 18, 2022 ? Trinseo PLC (Exact name of registrant as specified in its charter) ? ? ? ? ? ? Ireland ? 001-36473 ? N/A (State or other jurisdiction of incorporation or

Trinseo Provides Third Quarter 2022 Expected Results and Potential Profitability Improvement Initiatives; Announces Third Quarter 2022 Conference Call

Exhibit 99.1 ? ? ? ? ? Contact: Trinseo Andy Myers Tel : +1 610-240-3221 Email: [email protected] ? Trinseo Provides Third Quarter 2022 Expected Results and Potential Profitability Improvement Initiatives; Announces Third Quarter 2022 Conference Call WAYNE, Pa ? October 18, 2022 ? Trinseo (NYSE: TSE), a specialty material solutions provider, today released preliminary result estimates for third

TSE / Trinseo S.A. / M&G INVESTMENT MANAGEMENT LTD Activist Investment

United States SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 Trinseo PLC (Name of Issuer) Common Stock (Title of Class of Securities) G9059U107 (CUSIP Number) 1000 Chesterbrook Boulevard, Suite 300, Berwyn, PA 19312 (Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications) 09 August 2022 (Date o

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2022 ☐TRANSITION REPORT PURS

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2022 or ☐TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-

Amendment, dated May 9, 2022, to the Employment Agreement between Trinseo LLC and David Stasse dated April 29, 2019 (incorporated by reference to Exhibit 10.2 to the Quarterly Report on Form 10-Q for the quarter ended June 30, 2022 filed August 9, 2022)

Exhibit 10.2 Trinseo PLC 76 Sir John Rogerson’s Quay Dublin 2 D02 FX51, Ireland May 9, 2022 David Stasse E.V.P., Chief Financial Officer Dear Dave, We are pleased to confirm a change in your Change of Control benefit under your employment contract with Trinseo PLC or its affiliate. Basically, the change increases the severance amount from 18 months to 24 months provided all other conditions of thi

Agreement, dated May 9, 2022, to the Employment Agreement between Trinseo LLC and Angelo Chaclas dated January 1, 2020 (incorporated by reference to Exhibit 10.3 to the Quarterly Report on Form 10-Q for the quarter ended June 30, 2022 filed August 9, 2022)

Exhibit 10.3 Trinseo PLC 76 Sir John Rogerson’s Quay Dublin 2 D02 FX51, Ireland May 9, 2022 Angelo N. Chaclas S.V.P., Chief Legal Officer Dear Angelo, We are pleased to confirm a change in your Change of Control benefit under your employment contract with Trinseo PLC or its affiliate. Basically, the change increases the severance amount from 18 months to 24 months provided all other conditions of

Calculation of Filing Fee Table

? Exhibit 107 Calculation of Filing Fee Tables ? Form S-8 (Form Type) ? Trinseo PLC (Exact Name of Registrant as Specified in its Charter) ? Table 1: Newly Registered Securities ? Security Type Security Class Title Fee Calculation Rule Amount Registered Proposed Maximum Offering Price Per Share Maximum Aggregate Offering Price(2) Fee Rate Amount of Registration Fee(2) Equity Ordinary Shares, $0.

Amendment, dated May 9, 2022, to the Employment Agreement between Trinseo Europe GmbH and Andre Lanning dated October 1, 2021.

Exhibit 10.4 Trinseo PLC 76 Sir John Rogerson’s Quay Dublin 2 D02 FX51, Ireland May 9, 2022 Andre Lanning S.V.P., Chief Commercial Officer Dear Andre, We are pleased to confirm a change in your Change of Control benefit under your employment contract with Trinseo PLC or its affiliate. Basically, the change increases the severance amount from 18 months to 24 months provided all other conditions of

Powers of Attorney (included on the signature page of this Registration Statement).

As filed with the Securities and Exchange Commission on August 9, 2022 ? REGISTRATION NO.

Amendment, dated May 9, 2022, to the Employment Agreement between Trinseo Europe GmbH and Francesca Reverberi dated October 1, 2021 (incorporated by reference to Exhibit 10.5 to the Quarterly Report on Form 10-Q for the quarter ended June 30, 2022 filed August 9, 2022)

Exhibit 10.5 Trinseo PLC 76 Sir John Rogerson’s Quay Dublin 2 D02 FX51, Ireland May 9, 2022 Francesca Reverberi S.V.P., Chief Sustainability Officer Dear Francesca, We are pleased to confirm a change in your Change of Control benefit under your employment contract with Trinseo PLC or its affiliate. Basically, the change increases the severance amount from 18 months to 24 months provided all other

Amendment, dated May 9, 2022, to the Employment Agreement between Trinseo LLC and Frank Bozich dated December 11, 2018 (incorporated by reference to Exhibit 10.1 to the Quarterly Report on Form 10-Q for the quarter ended June 30, 2022 filed August 9, 2022)

Exhibit 10.1 Trinseo PLC 76 Sir John Rogerson’s Quay Dublin 2 D02 FX51, Ireland Frank A. Bozich President and Chief Executive Officer May 9, 2022 Dear Frank, We are advising you of a change in your Change of Control benefit under your employment contract with Trinseo PLC or its affiliate. Basically, the change increases the severance amount from 24 months to 36 months provided all other conditions

Current Report

? ? 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): August 8, 2022 ? Trinseo PLCs (Exact name of registrant as specified in its charter) ? ? ? ? ? ? Ireland ? 001-36473 ? N/A (State or other jurisdiction of incorporation or o

Summary 2022 Outlook Q2 2022 Results • Q2 cash use in operations of $83 million led to Free Cash Flow* of negative $115 million • Working capital use of $181 million attributed to steep increases in raw material and utility costs • Repurchased approx

Exhibit 99.2 ™ Trademark of Trinseo PLC or its affiliates Second Quarter 2022 Financial Results & Outlook August 8, 2022 2 Introductions & Disclosure Rules Disclosure Rules Cautionary Note on Forward-Looking Statements. This presentation may contain forward-looking statements including, without limitation, statements concerning plans, objectives, goals, projections, forecasts, strategies, future e

Trinseo Reports Second Quarter 2022 Financial Results and Updates Full-Year Outlook

Exhibit 99.1 ? ? ? ? ? Contact: Trinseo Andy Myers Tel : +1 610-240-3221 Email: [email protected] ? Trinseo Reports Second Quarter 2022 Financial Results and Updates Full-Year Outlook ? Second Quarter 2022 and Other Highlights ? ? Net income from continuing operations of $37 million and diluted EPS from continuing operations of $1.00 ? Adjusted EBITDA* of $164 million, including a $33 million fa

Memorandum and Articles of Association of Trinseo PLC, as amended (incorporated by reference to Exhibit 3.1 to the Current Report on Form 8-K, filed on June 17, 2022)

? ? COMPANIES ACT 2014 PUBLIC LIMITED COMPANY MEMORANDUM AND ARTICLES OF ASSOCIATION OF TRINSEO PLC ? Effective as of 13 July 2021 (as amended on 14 June 2022) ? ? ? ? ? ? COMPANIES ACT 2014 PUBLIC LIMITED COMPANY MEMORANDUM OF ASSOCIATION OF TRINSEO PLC 1.

Trinseo PLC Amended and Restated 2014 Omnibus Incentive Plan (incorporated by reference to Exhibit 10.1 to the Current Report on Form 8-K, filed on June 16, 2023)

TRINSEO PLC AMENDED AND RESTATED 2014 OMNIBUS INCENTIVE PLAN ? (Amended and Restated as of June 14, 2022) ? WHEREAS: ? A.

Current Report

? ? 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): June 14, 2022 ? Trinseo PLC (Exact name of registrant as specified in its charter) ? ? ? ? ? ? Ireland ? 001-36473 ? N/A (State or other jurisdiction of incorporation or org

TSE / Trinseo S.A. / M&G INVESTMENT MANAGEMENT LTD Activist Investment

United States SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 Trinseo PLC (Name of Issuer) Common Stock (Title of Class of Securities) G9059U107 (CUSIP Number) 1000 Chesterbrook Blvd., Suite 300, Berwyn, PA 19312 (Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications) 05 May 2022 (Date of Event

Form of Non-statutory Stock Option Award Agreement (incorporated by reference to Exhibit 10.4 to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 30, 2022 filed May 5, 2022)

? ? Name: /$ParticipantName$/ Number of Shares of Stock subject to Stock Option: /$AwardsGranted$/ Exercise Price Per Share: /$GrantPrice$/ Date of Grant: /$GrantDate$/ ? ? Exhibit 10.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2022 ☐TRANSITION REPORT PUR

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 ? ? FORM 10-Q ? ? ? (Mark One) ?QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2022 or ?TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File N

Form of Performance Award Stock Unit Agreement (incorporated by reference to Exhibit 10.5 to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 30, 2022 filed May 5, 2022)

Name: /$ParticipantName$/ Target Number of PSUs subject to Vesting and Performance Conditions: /$AwardsGranted$/ Date of Grant: /$GrantDate$/ ? Exhibit 10.

Form of Restricted Stock Unit Award Agreement (incorporated by reference to Exhibit 10.3 to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 30, 2022 filed May 5, 2022)

? ? ? ? Name: /$ParticipantName$/ Number of Restricted Stock Units subject to Award: /$AwardsGranted$/ Date of Grant: /$GrantDate$/ ? Exhibit 10.

Employment Agreement between Trinseo Europe GmbH and Francesca Reverberi dated October 1, 2021.

? Exhibit 10.2 TRINSEO EUROPE GMBH ? AMENDED AND RESTATED EMPLOYMENT AGREEMENT ? AMENDED AND RESTATED EMPLOYMENT AGREEMENT (this ?Agreement?), dated as of October 1, 2021, is among Trinseo Europe GmbH, a Swiss limited liability company (Gesellschaft mit beschr?nkter Haftung) (the ?Company?), and Francesca Reverberi of Bremgartnerstrasse 15, 8003 Zurich, Switzerland (the ?Executive?); which amends

Summary 2022 Outlook Q1 2022 Results•Q1 cash use in operations of $5 million led to Free Cash Flow** of negative $30 million; working capital use of $103 million from steep increase in raw material prices, sequential sales increase and inventory buil

Exhibit 99.2 ?Trademark of Trinseo PLC or its affiliates First Quarter 2022 Financial Results & OutlookMay 4, 2022 2 Introductions & Disclosure RulesDisclosure RulesCautionary Note on Forward-Looking Statements.This presentation may contain forward-looking statements including, without limitation, statements concerning plans, objectives, goals, projections, forecasts, strategies, future events or

Trinseo Reports First Quarter 2022 Financial Results and Updates Full-Year Outlook

Exhibit 99.1 ? ? ? ? ? ? ? Press Contact: ? Investor Contact: Trinseo ? Trinseo Dina Pokedoff ? Andy Myers Tel : +1 610-240-3307 ? Tel : +1 610-240-3221 Email: [email protected] ? Email: [email protected] ? Trinseo Reports First Quarter 2022 Financial Results and Updates Full-Year Outlook ? First Quarter 2022 and Other Highlights ? ? Net income from continuing operations of $17 million and d

Current Report

? ? 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 4, 2022 ? Trinseo PLC (Exact name of registrant as specified in its charter) ? ? ? ? ? ? Ireland ? 001-36473 ? N/A (State or other jurisdiction of incorporation or organ

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

DEF 14A 1 tm223624-3def14a.htm DEF 14A TABLE OF CONTENTS UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant  ☒ Filed by a Party other than the Registrant  ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, for Use of the Commission Only

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

DEFA14A 1 tm223624d4defa14a.htm DEFA14A UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant þ Filed by a Party other than the Registrant ¨ Check the appropriate box: ¨ Preliminary Proxy Statement ¨ Confidential, for Use of the Commission Only (as permitted by Ru

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

TABLE OF CONTENTS UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant  ☒ Filed by a Party other than the Registrant  ☐ Check the appropriate box: ☒ Preliminary Proxy Statement ☐ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ☐ De

Trinseo Net Sales by Region and EMEA by Country 2021 Net Sales by Geography1 2021 EMEA* Net Sales by Country2 Aus tria 3% Othe r 2% Be lgium 6% Finland 4% Cze ch Re public 4% France 5% Unite d Kingdom 4% Othe r 12.5% Unite d State s 19% urk e y EM EA

Exhibit 99.1 ? Trinseo Net Sales by Region and EMEA by Country 2021 Net Sales by Geography1 2021 EMEA* Net Sales by Country2 Aus tria 3% Othe r 2% Be lgium 6% Finland 4% Cze ch Re public 4% France 5% Unite d Kingdom 4% Othe r 12.5% Unite d State s 19% urk e y EM EA* 57% Ne the rlands 4% Sw e de n 5% Spain As ia Pacific 22% Ge rm any 28% 3% Poland 4% Portugal Egypt Hungary Ireland Russia Romania Sl

Financial Statements and Exhibits

? ? 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): February 25, 2022 ? Trinseo PLC (Exact name of registrant as specified in its charter) ? ? ? ? ? ? Ireland ? 001-36473 ? N/A (State or other jurisdiction of incorporation or

Trinseo PLC Amended and Restated 2014 Omnibus Incentive Plan

Exhibit 10.30 TRINSEO PLC AMENDED AND RESTATED 2014 OMNIBUS INCENTIVE PLAN ? (As Assumed, Amended and Restated as of October 8, 2021) ? WHEREAS: ? A.On May 30, 2014, Trinseo S.A., a public limited company (soci?t? anonyme) incorporated under the laws of Luxembourg adopted the Trinseo S.A. 2014 Omnibus Incentive Plan (as so adopted and amended, from time to time, in respect of periods prior to the

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K ? ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended: December 31, 2021 ? TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-36473 Trinseo P

Memorandum and Articles of Association of Trinseo PLC

Exhibit 3.1 COMPANIES ACT 2014 PUBLIC LIMITED COMPANY MEMORANDUM AND ARTICLES OF ASSOCIATION OF TRINSEO PLC ? Effective as of 13 July 2021 ? ? ? COMPANIES ACT 2014 PUBLIC LIMITED COMPANY MEMORANDUM OF ASSOCIATION OF TRINSEO PLC ? 1. The name of the Company is: Trinseo PLC. 2. The Company is a public limited company for the purposes of Part 17 of the Companies Act 2014 (the ?Act?). 3. The objects f

Description of Securities

Exhibit 4.3 DESCRIPTION OF SECURITIES References to ?we?, ?us?, ?Trinseo? or the ?Company? herein are, unless the context otherwise indicates, only to Trinseo PLC and not to any of its subsidiaries. General The following is a summary of information concerning capital stock of Trinseo PLC. The summaries and descriptions below do not purport to be complete statements of the relevant provisions of th

Subsidiaries of Trinseo PLC

Exhibit 21.1 SUBSIDIARIES OF TRINSEO PLC JANUARY 31, 2022 ENTITY NAME JURISDICTION Trinseo Belgium B.V. Belgium Trinseo Canada ULC Canada Trinseo Polymers (Zhangjiagang) Company Limited China Altuglas International Denmark A/S Denmark Trinseo Suomi Oy Finland Altuglas International S.A.S. France Trinseo France S.A.S. France Trinseo Deutschland Anlagengesellschaft MbH Germany Trinseo Deutschland Gm

Form of Non-statutory Stock Option Award Agreement

Exhibit 10.34 Name: /$ParticipantName$/ Number of Shares of Stock subject to Stock Option: /$AwardsGranted$/ Exercise Price Per Share: /$GrantPrice$/ Date of Grant: /$GrantDate$/ ? ? TRINSEO PLC Amended & Restated 2014 Omnibus Incentive Plan Non-Statutory Stock Option Agreement ? This agreement (this ?Agreement?) evidences an award (the ?Award?) of a stock option (the ?Stock Option?) granted by Tr

Form of Performance Award Stock Unit Agreement

Exhibit 10.35 ? ? ? ? ? ? Name: /$ParticipantName$/ Target Number of PSUs subject to Vesting and Performance Conditions: /$AwardsGranted$/ Date of Grant: /$GrantDate$/ ? TRINSEO S.A. Amended & Restated 2014 Omnibus Incentive Plan Performance Award Stock Unit Agreement ? This agreement (this ?Agreement?) evidences an award (the ?Award?) of restricted stock units subject to performance conditions (h

Form of Restricted Stock Unit Award Agreement

Exhibit 10.33 Name: /$ParticipantName$/ Number of Restricted Stock Units subject to Award: /$AwardsGranted$/ Date of Grant: /$GrantDate$/ ? Trinseo PLC Amended & Restated 2014 Omnibus Incentive Plan Restricted Stock Unit Agreement ? This agreement (this ?Agreement?) evidences an award (the ?Award?) of restricted stock units (the ?Restricted Stock Units?) granted by Trinseo PLC (the ?Company?) to t

Trinseo Creates Two, Key Executive Leadership Team Roles; Appoints André Lanning to Chief Commercial Officer Role

? ? ? ? ? ? Press Contact: ? Investor Contact: Trinseo ? Trinseo Dina Pokedoff ? Andy Myers Tel : +1 610-240-3307 ? Tel : +1 610-240-3221 Email: dpokedoff@trinseo.

Amendment, dated February 17, 2022, to the Employment Agreement between Trinseo Europe GmbH and Andre Lanning dated October 1, 2021

? ? ? ? Trinseo PLC 76 Sir John Rogerson?s Quay Dublin 2 D02 FX51, Ireland ? 16 February 2022 ? Dear Andr?, ? We are pleased to confirm our offer for the position of Senior Vice President & Chief Commercial Officer with Trinseo Europe GmbH based in Switzerland, with effect of 1 March 2022.

Financial Statements and Exhibits

? ? 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): February 17, 2022 ? Trinseo PLC (Exact name of registrant as specified in its charter) ? ? ? ? ? ? Ireland ? 001-36473 ? N/A (State or other jurisdiction of incorporation or

LU:TSE / Trinseo SA / ALLIANCEBERNSTEIN L.P. Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. 2 )* Trinseo SA (Name of Issuer) Common Stock (Title of Class of Securities) L9340P101 (CUSIP Number) December 31, 2021 (Date of Event Which Requires Filing of this Statement) Check the appropriate box to designate the rule pursuant to which this Schedule is

Current Report

? ? 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): February 8, 2022 ? Trinseo PLC (Exact name of registrant as specified in its charter) ? ? ? ? ? ? Ireland ? 001-36473 ? N/A (State or other jurisdiction of incorporation or

™Trademark of Trinseo PLC or its affiliates Fourth Quarter 2021 Financial Results & 2022 OutlookFebruary 8, 2022 Summary 2022 Outlook Q4 2021 Results•Q4 cash from operations of $214 million led to Free Cash Flow* of $159 million; included a working c

Exhibit 99.2 ?Trademark of Trinseo PLC or its affiliates Fourth Quarter 2021 Financial Results & 2022 OutlookFebruary 8, 2022 2 Introductions & Disclosure RulesDisclosure RulesCautionary Note on Forward-Looking Statements.This presentation may contain forward-looking statements including, without limitation, statements concerning plans, objectives, goals, projections, forecasts, strategies, future

Trinseo Reports Fourth Quarter and Full Year 2021 Financial Results; Provides Full Year 2022 Guidance

EX-99.1 2 tse-20220208xex99d1.htm EX-99.1 Exhibit 99.1 Press Contact: Investor Contact: Trinseo Trinseo Dina Pokedoff Andy Myers Tel : +1 610-240-3307 Tel : +1 610-240-3221 Email: [email protected] Email: [email protected] Trinseo Reports Fourth Quarter and Full Year 2021 Financial Results; Provides Full Year 2022 Guidance Full Year 2021 Summary ● Net income from continuing operations of $28

Trinseo Provides Fourth Quarter and Full Year 2021 Expected Results and Full Year 2022 Estimates; Announces Fourth Quarter 2021 Conference Call

EX-99.1 2 tse-20220124xex99d1.htm EX-99.1 Exhibit 99.1 Press Contact: Investor Contact: Trinseo Trinseo Dina Pokedoff Andy Myers Tel : +1 610-240-3307 Tel : +1 610-240-3221 Email: [email protected] Email: [email protected] Trinseo Provides Fourth Quarter and Full Year 2021 Expected Results and Full Year 2022 Estimates; Announces Fourth Quarter 2021 Conference Call Fourth Quarter 2021 Expecte

Current Report

? ? 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): January 24, 2022 ? Trinseo PLC (Exact name of registrant as specified in its charter) ? ? ? ? ? ? Ireland ? 001-36473 ? N/A (State or other jurisdiction of incorporation or

Financial Statements and Exhibits, Other Events

? ? 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): December 2, 2021 ? Trinseo PLC (Exact name of registrant as specified in its charter) ? ? ? ? ? ? Ireland ? 001-36473 ? N/A (State or other jurisdiction of incorporation or

Trinseo Completes Sale of Synthetic Rubber Business to Synthos S.A. Close of sale will serve as an additional catalyst for helping Trinseo transform into a higher margin, less cyclical specialty materials and sustainable solutions provider

? ? ? ? ? ? Press Contact: ? Investor Contact: Trinseo ? Trinseo Dina Pokedoff ? Andy Myers Tel : +1 610-240-3307 ? Tel : +1 610-240-3221 Email: dpokedoff@trinseo.

Entry into a Material Definitive Agreement, Financial Statements and Exhibits, Completion of Acquisition or Disposition of Assets, Other Events

? ? 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): December 1, 2021 ? Trinseo PLC (Exact name of registrant as specified in its charter) ? ? ? ? ? ? Ireland ? 001-36473 ? N/A (State or other jurisdiction of incorporation or

Dina Pokedoff

? ? ? ? ? ? Press Contact: ? Investor Contact: Trinseo ? Trinseo Dina Pokedoff ? Andy Myers Tel : +1 610-240-3307 ? Tel : +1 610-240-3221 Email: dpokedoff@trinseo.

Form of Indemnification Agreement for Directors and Officers.

Exhibit 10.1 DEED OF INDEMNIFICATION ? This Deed of Indemnification (?Deed?) is made as of October 8, 2021 by and between Trinseo PLC, a public limited company incorporated under the laws of Ireland (the ?Company?), and [] (?Indemnitee?). ? WHEREAS on the date hereof, the re-domiciliation of Trinseo S.A. from Luxembourg to Ireland pursuant to a merger by acquisition under the European Communities

Employment Agreement between Trinseo Europe GmbH and Andre Lanning dated October 1, 2021.

Exhibit 10.2 TRINSEO EUROPE GMBH ? AMENDED AND RESTATED EMPLOYMENT AGREEMENT ? AMENDED AND RESTATED EMPLOYMENT AGREEMENT (this ?Agreement?), dated as of October 1, 2021, is among Trinseo Europe GmbH, a Swiss limited liability company (Gesellschaft mit beschr?nkter Haftung) (the ?Company?), and Andre Lanning of Seestrasse 79C 8800 Thalwil, Switzerland (the ?Executive?); which amends and restates th

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2021 ☐TRANSITION REPORT

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 ? ? FORM 10-Q ? ? ? (Mark One) ?QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2021 or ?TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission Fi

Amendment Agreement, dated October 21, 2021, to Asset Purchase Agreement, by and between Trinseo PLC, Trinseo Deutschland GmbH, Trinseo Europe GmbH, Trinseo Belgium B.V.B.A., Trinseo Export GmbH, and Synthos PLC, Blitz F21-410 GmbH, and Synthos Dwory 7 dated May 21, 2021.

Exhibit 10.5 deed no. 1254 / 2021 S Recorded at Frankfurt am Main, on 21 October 2021 Before me, the undersigned notary in the district of the Higher Regional Court of Frankfurt am Main, Dr Bernhard Sch?tz with official place of business at 60325 Frankfurt am Main, Bockenheimer Landstra?e 13-15, appeared today, all identified by their valid official photo-identification documents: 1. Ms Lara Stelm

Form of Restricted Stock Unit Award Agreement to certain former Arkema employees (incorporated herein by reference to Exhibit 10.3 to the Quarterly Report on Form 10-Q for the quarter ended September 30, 2021, filed on November 8, 2021)

Exhibit 10.3 Name: /$ParticipantName$/ Number of Restricted Stock Units subject to Award: /$AwardsGranted$/ Date of Grant: /$GrantDate$/ ? TRINSEO S.A. Amended & Restated 2014 Omnibus Incentive Plan Restricted Stock Unit Agreement ? This agreement (this ?Agreement?) evidences an award (the ?Award?) of restricted stock units (the ?Restricted Stock Units?) granted by Trinseo S.A. (the ?Company?) to

Form of Stock Option Award Agreement to certain former Arkema employees (incorporated herein by reference to Exhibit 10.4 to the Quarterly Report on Form 10-Q for the quarter ended September 30, 2021, filed on November 8, 2021)

EX-10.4 5 tse-20210930xex10d4.htm EX-10.4 Exhibit 10.4 Name: /$ParticipantName$/ Number of Shares of Stock subject to Stock Option: /$AwardsGranted$/ Exercise Price Per Share: /$GrantPrice$/ Date of Grant: /$GrantDate$/ TRINSEO S.A. Amended & Restated 2014 Omnibus Incentive Plan Non-Statutory Stock Option Agreement This agreement (this “Agreement”) evidences an award (the “Award”) of a stock optio

Current Report

? ? 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): November 5, 2021 ? Trinseo PLC (Exact name of registrant as specified in its charter) ? ? ? ? ? ? Ireland ? 001-36473 ? N/A (State or other jurisdiction of incorporation or

Trinseo Reports Third Quarter 2021 Financial Results; Announces Planned Divestiture of Styrenics Businesses

Exhibit 99.1 ? ? ? ? ? ? ? Press Contact: ? Investor Contact: Trinseo ? Trinseo Dina Pokedoff ? Andy Myers Tel : +1 610-240-3307 ? Tel : +1 610-240-3221 Email: [email protected] ? Email: [email protected] ? Trinseo Reports Third Quarter 2021 Financial Results; Announces Planned Divestiture of Styrenics Businesses ? Third Quarter 2021 and Other Highlights ? ? Strong net income from continuing

™Trademark of Trinseo PLC or its affiliates Third Quarter 2021 Financial Results & Outlook November 5, 2021 Summary 2021 Outlook Q3 2021 Results • Q3 cash provided by operations of $208 million led to Free Cash Flow* of $173 million; working capital

Exhibit 99.2 ?Trademark of Trinseo PLC or its affiliates Third Quarter 2021 Financial Results & Outlook November 5, 2021 2 Introductions & Disclosure Rules Disclosure Rules Cautionary Note on Forward-Looking Statements.This presentation may contain forward-looking statements including, without limitation, statements concerning plans, objectives, goals, projections, forecasts, strategies, future ev

Separation Agreement with Alice Heezen dated October 25, 2021

Personal and Confidential Delivered Via Email ? ? Alice Heezen Z?rcherstrasse 21 8853 Lachen Switzerland Horgen, 21 October 2021 ? ? Separation Agreement ? Dear Alice, ? We would like to summarize the mutually agreed to details concerning your resignation and separation from Trinseo Europe GmbH on 30 April 2022, unless otherwise adjusted as described below.

Current Report

? ? 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): October 21, 2021 ? Trinseo PLC (Exact name of registrant as specified in its charter) ? ? ? ? ? ? Ireland ? 001-36473 ? N/A (State or other jurisdiction of incorporation or

Trinseo Appoints Paula Cooney as Senior Vice President, Chief Human Resources Officer

? ? ? ? ? ? Press Contact: ? Investor Contact: Trinseo ? Trinseo Dina Pokedoff ? Andy Myers Tel : +1 610-240-3307 ? Tel : +1 610-240-3221 Email: dpokedoff@trinseo.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 15 CERTIFICATION AND NOTICE OF TERMINATION OF REGISTRATION UNDER SECTION 12(g) OF THE SECURITIES EXCHANGE ACT OF 1934 OR SUSPENSION OF DUTY TO FILE REPORTS UNDER SECTIONS 13

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 15 CERTIFICATION AND NOTICE OF TERMINATION OF REGISTRATION UNDER SECTION 12(g) OF THE SECURITIES EXCHANGE ACT OF 1934 OR SUSPENSION OF DUTY TO FILE REPORTS UNDER SECTIONS 13 AND 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 Commission File Number 001-36473 TRINSEO S.A. (Exact name of registrant as specified in its charter)

Trinseo PLC Amended and Restated 2014 Omnibus Incentive Plan

Exhibit 4.2 TRINSEO PLC AMENDED AND RESTATED 2014 OMNIBUS INCENTIVE PLAN (As Assumed, Amended and Restated as of October 8, 2021) WHEREAS: A. On May 30, 2014, Trinseo S.A., a public limited company (soci?t? anonyme) incorporated under the laws of Luxembourg adopted the Trinseo S.A. 2014 Omnibus Incentive Plan (as so adopted and amended, from time to time, in respect of periods prior to the Effecti

As filed with the Securities and Exchange Commission on October 8, 2021

As filed with the Securities and Exchange Commission on October 8, 2021 Registration Nos.

As filed with the Securities and Exchange Commission on October 8, 2021

As filed with the Securities and Exchange Commission on October 8, 2021 Registration Nos.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K12B CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): October 8, 2021 Trinseo PLC (E

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K12B CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): October 8, 2021 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

Press Release dated October 8, 2021

Exhibit 99.1 Press Contact: Investor Contact: Trinseo Trinseo Dina Pokedoff Andy Myers Tel : +1 610-240-3307 Tel : +1 610-240-3221 Email: [email protected] Email: [email protected] Trinseo: Redomiciliation of Parent Company Trinseo Announces Redomiciliation of Parent Company from Luxembourg to Ireland BERWYN, Pa ? September 28, 2021 ? Trinseo (NYSE: TSE), a global materials solutions provide

Trinseo PLC Amended and Restated 2014 Omnibus Incentive Plan

Exhibit 4.2 TRINSEO PLC AMENDED AND RESTATED 2014 OMNIBUS INCENTIVE PLAN (As Assumed, Amended and Restated as of October 8, 2021) WHEREAS: A. On May 30, 2014, Trinseo S.A., a public limited company (soci?t? anonyme) incorporated under the laws of Luxembourg adopted the Trinseo S.A. 2014 Omnibus Incentive Plan (as so adopted and amended, from time to time, in respect of periods prior to the Effecti

EX-99.25

NOTIFICATION OF THE REMOVAL FROM LISTING AND REGISTRATION OF THE STATED SECURITIES The New York Stock Exchange hereby notifies the SEC of its intention to remove the entire class of the stated securities from listing and registration on the Exchange at the opening of business on October 19, 2021, pursuant to the provisions of Rule 12d2-2 (a).

As filed with the Securities and Exchange Commission on October 8, 2021

As filed with the Securities and Exchange Commission on October 8, 2021 Registration Nos.

Trinseo PLC Amended and Restated 2014 Omnibus Incentive Plan

Exhibit 4.2 TRINSEO PLC AMENDED AND RESTATED 2014 OMNIBUS INCENTIVE PLAN (As Assumed, Amended and Restated as of October 8, 2021) WHEREAS: A. On May 30, 2014, Trinseo S.A., a public limited company (soci?t? anonyme) incorporated under the laws of Luxembourg adopted the Trinseo S.A. 2014 Omnibus Incentive Plan (as so adopted and amended, from time to time, in respect of periods prior to the Effecti

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2021 ☐TRANSITION REPORT PURS

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 ? ? FORM 10-Q ? ? ? (Mark One) ?QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2021 or ?TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Nu

Second Quarter 2021 Financial Results & Outlook August 4, 2021 3 Summary • Favorable demand trends from Q1 continued in most applications including construction, appliances and packaging • Includes two months of results from the newly acquired PMMA b

Exhibit 99.2 Second Quarter 2021 Financial Results & Outlook August 4, 2021 2 Disclosure Rules Cautionary Note on Forward-Looking Statements. This presentation contains forward-looking statements including, without limitation, statements concerning plans, objectives, goals, projections, strategies, future events or performance, and underlying assumptions and other statements, which are not stateme

Current Report

? ? 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): August 4, 2021 ? Trinseo S.A. (Exact name of registrant as specified in its charter) ? ? ? ? ? ? Luxembourg ? 001-36473 ? N/A (State or other jurisdiction of incorporation o

Trinseo Reports Record Second Quarter 2021 Financial Results

Exhibit 99.1 ? ? ? ? ? ? ? Press Contact: ? Investor Contact: Trinseo ? Trinseo Dina Pokedoff ? Andy Myers Tel : +1 610-240-3307 ? Tel : +1 610-240-3221 Email: [email protected] ? Email: [email protected] ? Trinseo Reports Record Second Quarter 2021 Financial Results ? Second Quarter 2021 and Other Highlights ? ? Strong net income from continuing operations of $133 million and diluted EPS fr

Purchase and Sale Agreement by and among Trinseo US Holding, Inc., Trinseo Europe GmbH, Trinseo S.A., Aristech Surfaces LLC and SK AA Holdings, LLC dated July 19, 2021.*

? ? ? PURCHASE AND SALE AGREEMENT by and among TRINSEO US HOLDING, INC., TRINSEO EUROPE GMBH, TRINSEO S.A., ARISTECH SURFACES LLC and SK AA HOLDINGS, LLC ? ? Dated as of July 19, 2021 ? ? ? -1- Article I DEFINITIONS?1 Section 1.1.Definitions?1 Article II PURCHASE AND SALE?1 Section 2.1.Purchase and Sale of the Purchased Interests?1 Section 2.2.Closing?2 Section 2.3.Transactions to Be Effected at t

Current Report

? ? 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): July 19, 2021 ? Trinseo S.A. (Exact name of registrant as specified in its charter) ? ? ? ? ? ? Luxembourg ? 001-36473 ? N/A (State or other jurisdiction of incorporation or

Trinseo to Acquire Aristech Surfaces LLC as Part of its Transformation to a Specialty Materials and Sustainable Solutions Provider

Exhibit 99.1 Press Contact: Investor Contact: Trinseo Trinseo Dina Pokedoff Andy Myers Tel : +1 610-240-3307 Tel : +1 610-240-3221 Email: [email protected] Email: [email protected] Trinseo to Acquire Aristech Surfaces LLC as Part of its Transformation to a Specialty Materials and Sustainable Solutions Provider ? Strengthens Trinseo?s strong position in acrylic solutions and drives expansion

Regulation FD Disclosure

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): July 19, 2021 Trinseo S.A. (Exact name of registrant as specified in its charter) Luxembourg 001-36473 N/A (State or other jurisdiction of incorporation or organization) (Commission F

ΠTrademark of Trinseo S.A. or its affiliates Acquisition of Aristech Surfaces July 19, 2021

Exhibit 99.2 ? Trademark of Trinseo S.A. or its affiliates Acquisition of Aristech Surfaces July 19, 2021 2 Presenters & Disclosure Rules Presenters ? Frank Bozich, President & CEO ? David Stasse, Executive Vice President & CFO ? Andy Myers, Director of Investor Relations Disclosure Rules Cautionary Note on Forward - Looking Statements. This presentation may contain forward - looking statements in

Financial Statements and Exhibits, Completion of Acquisition or Disposition of Assets

? ? UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K/A (Amendment No. 1) 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 3, 2021 Trinseo S.A. (Exact name of registrant as specified in its charter) ? ? ? ? Luxembourg 001-36473 N/A (State or other jurisdiction of incorporation

UNAUDITED PRO FORMA COMBINED FINANCIAL INFORMATION

Exhibit 99.2 UNAUDITED PRO FORMA COMBINED FINANCIAL INFORMATION On May 3, 2021, Trinseo S.A., (together with its subsidiaries, the ?Company? or ?Trinseo?), completed its previously-announced acquisition of the polymethyl methacrylates (?PMMA?) and activated methyl methacrylates (?MMA?) business (together, the ?PMMA business?) of Arkema S.A., (?Arkema? or the ?Seller?) through the purchase of share

ERNST & YOUNG Audit

? Exhibit 99.1 ? ? ? ? ? ? ERNST & YOUNG Audit ? KPMG Audit ? Ernst & Young Audit ? Tour EQHO ? Tour First ? 2 Avenue Gambetta ? 1-2, Place des Saisons ? CS 60055 ? 92400 Courbevoie ? 92066 Paris la D?fense Cedex ? France ? France ? ? ? ? Independent Auditors? Report ARKEMA S.A. Registered office: 420, rue d?Estienne d?Orves 92700 Colombes FRANCE ? ? Years ended December 31, 2020 and 2019 ? ? To t

Current Report

? ? 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): June 14, 2021 ? Trinseo S.A. (Exact name of registrant as specified in its charter) ? ? ? ? ? ? Luxembourg ? 001-36473 ? N/A (State or other jurisdiction of incorporation or

Amended and Restated Articles of Association of Trinseo S.A., as amended (incorporated herein by reference to Exhibit 3.1 to the Current Report on Form 8-K filed June 17, 2021).

? ? ? ? Trinseo S.A. ? Soci?t? Anonyme 26-28, rue Edward Steichen L-2540 Luxembourg (Grand-Duch? de Luxembourg) R.C.S. Luxembourg: B153549 (la ? Soci?t? ? ) ? ? ? La Soci?t? a ?t? constitu?e en date du 3 juin 2010 suivant un acte notari?, publi? au M?morial C, Recueil des Soci?t?s et Associations num?ro 1466 du 16 juillet 2010. ? Les Statuts ont ?t? modifi?s en dernier lieu en date du 14 juin 2021

Trinseo Announces Sale of Synthetic Rubber Business to Synthos S.A. for $491 Million

Exhibit 99.1 ? Trinseo Announces Sale of Synthetic Rubber Business to Synthos S.A. for $491 Million ? BERWYN, Pa. May 21, 2021 - Trinseo (NYSE: TSE), a global materials company and manufacturer of plastics, latex binders and synthetic rubber, announced today it has entered into a definitive agreement to sell its synthetic rubber business based in Schkopau, Germany (?Synthetic Rubber? or the ?Busin

Asset Purchase Agreement, by and between Trinseo S.A., Trinseo Deutschland GmbH, Trinseo Europe GmbH, Trinseo Belgium B.V.B.A., Trinseo Export GmbH, and Synthos S.A., Blitz F21-410 GmbH, and Synthos Dwory 7 dated May 21, 2021.*

EX-10.1 2 tse-20210521xex10d1.htm EX-10.1 Exhibit 10.1 deed no. 582 I 2021 S R e c o r d e d at Frankfurt am Main, on 21 May 2021 Before me, the undersigned notary in the district of the Higher Regional Court of Frankfurt am Main, Dr Bernhard Schutz with official place of business at 60325 Frankfurt am Main, Bockenheimer Landstral3e 13-15, appeared today, all identified by their valid official pho

Entry into a Material Definitive Agreement, Financial Statements and Exhibits, Other Events

? ? 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 21, 2021 ? Trinseo S.A. (Exact name of registrant as specified in its charter) ? ? ? ? ? ? Luxembourg ? 001-36473 ? N/A (State or other jurisdiction of incorporation or