Taiwan Styrene Monomer Corporation Announces Resignation of Corporate Directors

Release Date: June 19, 2026 Statement Date: June 18, 2026 Statement Time: 15:31:13 Company Code: 1310 Company Name: Taiwan Styrene Monomer Corporation Subject: Announcement of Resignation of Corporate Directors Applicable Clause: Clause 6 Event Date: June 18, 2026

Details: 1. Date of Change: June 18, 2026 2. Category of Appointed or Changed Personnel (Corporate Director, Corporate Supervisor, Independent Director, Individual Director, or Individual Supervisor): Corporate Director 3. Former Personnel Title and Name: (1) Corporate Director: Anqing Development Co., Ltd. (Representative: Hsu Ting-jui) (2) Corporate Director: Kaijiang Co., Ltd. (Representative: Chang Kuo-chin) 4. Former Personnel Background: Corporate Director of Taiwan Styrene Monomer Corporation 5. New Personnel Title and Name: Not applicable 6. New Personnel Background: Not applicable 7. Nature of Change (Please select from 'Resignation', 'Dismissal', 'End of Term', 'Deceased', or 'New Appointment'): Resignation 8. Reason for Change: Resignation of Corporate Directors 9. Number of Shares Held by New Appointee at Time of Election: Not applicable 10. Original Term (e.g., 2024/05/31 ~ 2027/05/30): May 31, 2024 ~ May 30, 2027 11. Effective Date of New Appointment: Not applicable 12. Ratio of Director Changes Within Same Term: 2/11 13. Ratio of Independent Director Changes Within Same Term: Not applicable 14. Ratio of Supervisor Changes Within Same Term: None 15. Is the Change Involving One-Third or More of Directors? (Yes or No): No 16. Other Matters to be Clarified: The company received resignation letters from its corporate directors on June 18, 2026, effective on the same date.