X0508 4 2025-02-27 0001519061 Trinseo PLC TSE 0001441657 Stasse David Phillip C/O TRINSEO PLC 440 EAST SWEDESFORD ROAD, SUITE 301 WAYNE PA 19087 false true false false EVP AND CFO 0 Ordinary Shares 2025-02-27 4 A 0 123745 0 A 279853 D Represents ordinary shares issuable pursuant to RSU awards that will vest in three equal annual installments beginning on the first anniversary of the date of grant. /s/ Angelo Chaclas, Attorney-in-Fact 2025-03-03