1301 Formosa Plastics to Participate in E.Sun Securities' Corporate Briefing Session

Announcement Date: June 26, 2026 Statement Date: June 25, 2026 Statement Time: 17:17:55 Company Code: 1301 Company Name: Formosa Plastics Corporation Subject: Announcement of Invitation to Participate in E.Sun Securities' Corporate Presentation Applicable Clause: Clause 12 Factual Date: June 26, 2026

Details: Applicable under Article 4, Paragraph XX: 12 Factual Date: June 26, 2026

1. Date of Corporate Presentation: June 26, 2026 2. Time of Corporate Presentation: 3:30 PM 3. Venue: Online Conference 4. Summary of Presentation: Formosa Plastics has been invited to participate in E.Sun Securities' online corporate briefing to present an overview of its business operations. 5. Additional Notes: Registration inquiries should be directed to E.Sun Securities via email at Gina0823-72190@esunsec.com.tw For complete financial and business information, please visit the Corporate Presentations section on Taiwan's Public Information Observation Station website.