Exhibit 99.1 Contact: Andy Myers Tel : +1 610-240-3221 Email: aemyers@trinseo.com 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 used in operations of $66 million and capital expenditures of $16 million resulted in Free Cash Flow* of negative $ ...