Taiwan Styrene Monomer Announces Resignation of Corporate Directors

1. Date of Change: June 18, 2026 (Minguo Year 115)

2. Type of Appointment or Change (please select from Corporate Director, Corporate Supervisor, Independent Director, Individual Director, or Individual Supervisor): Corporate Director

3. Former Position 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 Director's Background: Corporate Director of Taiwan Styrene Monomer Corporation

5. New Director's Position and Name: Not applicable

6. New Director's Background: Not applicable

7. Nature of Change (please enter 'Resignation', 'Removal', 'End of Term', 'Deceased', or 'New Appointment'): Resignation

8. Reason for Change: Resignation of corporate director

9. Number of Shares Held by New Director at Time of Appointment: Not applicable

10. Original Term (e.g., xx/xx/xx ~ xx/xx/xx): May 31, 2024 ~ May 30, 2027 (Minguo 113 ~ 116)

11. Effective Date of New Appointment: Not applicable

12. Turnover Rate of Directors During Same Term: 2/11

13. Turnover Rate of Independent Directors During Same Term: Not applicable

14. Turnover Rate of Supervisors During Same Term: None

15. Is the Change Involving One-Third or More of the Directors? (Please enter Yes or No): No

16. Other Matters to be Clarified: The company received resignation letters from its corporate directors on June 18, 2026 (Minguo Year 115), effective immediately on the same date. This announcement qualifies as material information under Article 7, Paragraph 6, Item 6 of the Enforcement Rules of the Securities and Exchange Act, as it may significantly affect shareholder rights or securities prices, given that the entity involved is a publicly issued company.