Material Agreement Form 8 K

As previously announced on December 10, 2024, Trinseo PLC (the "Company"), and certain of its direct and indirect subsidiaries, entered into a transaction support agreement dated December 9, 2024 (the "Transaction Support Agreement").

The description of the Transaction Support Agreement included in the Company's Current Report on Form 8-K dated December 10, 2024, and the transactions contemplated thereby is not complete and is qualified in its entirety by the Transaction Support Agreement, a copy of which is attached hereto as Exhibit 10.1 and incorporated herein by reference.