The unaudited interim condensed consolidated financial statements of Trinseo PLC and its subsidiaries (the “Company”) as of and for the periods ended June 30, 2025 and 2024 were prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and reflect all adjustments, consisting only of normal recurring adjustments, which, in the opinion of management, are considered necessary for the fair statement of the results for the periods presented. Because they cover interim periods, the statements and related notes to the financial statements do not include all disclosures normally provided in annual financial statements, and therefore, these statements should be read in conjunction with the 2024 audited consolidated financial statements included within the Company’s Annual Report on Form 10-K (“Annual Report”) filed with the Securities and Exchange Commission (“SEC”) on February 27, 2025. The Company’s condensed consolidated financial statements presented herein reflect the latest estimates and assumptions made by management that affect the reported amounts and related disclosures as of and for the period ended June 30, 2025. However, actual results could differ from these estimates and assumptions.

The December 31, 2024 condensed consolidated balance sheet data presented herein was derived from the Company’s December 31, 2024 audited consolidated financial statements but does not include all disclosures required by GAAP for annual periods.

Effective October 1, 2024, the Company changed the management of its businesses to better reflect the Company’s strategic focus on providing solutions in areas such as sustainability and material substitution. The Compounding business within the Plastics Solutions segment was combined with the Engineered Materials segment, while the remaining Plastics Solutions businesses were combined with the Polystyrene segment and renamed Polymer Solutions. As a result, the Company realigned its reporting segments to reflect the new model under which the business is managed with four segments, all of which remain unchanged from the Company’s prior segmentation: Engineered Materials, Latex Binders, Polymer Solutions, and Americas Styrenics. Therefore, certain prior year information has been recast to reflect the current segment structure. Refer to Notes 3, 4 and 16 for further information.

Throughout this Quarterly Report, unless otherwise indicated, amounts and activity are presented on a continuing operations basis.