Trinseo (TSE) Proxy filing summary

Executive summary

• Annual General Meeting scheduled for September 23, 2026, with participation options in the US and Ireland.

• Proxy materials and voting instructions are available online, by phone, or by mail.

• Shareholders are encouraged to opt for electronic delivery to support environmental initiatives.

Voting matters and shareholder proposals

• Election of eleven directors is proposed, with the Board recommending a vote FOR all nominees.

• Advisory vote on executive compensation (say-on-pay) is included.

• Ratification of PricewaterhouseCoopers LLP as independent auditor for 2026 and authorization for the Audit Committee to set remuneration.

• Other business may be addressed as appropriate at the meeting.

Board of directors and corporate governance

• Proxy appoints Frank A. Bozich, David Stasse, and Angelo Chaclas as representatives to vote on behalf of shareholders.

• Board recommends voting in favor of all proposals and nominees.