Formosa Plastics Announces Acquisition of Equity in Formosa Daicel Fine Chemicals Co., Ltd.

1. Name and nature of the subject matter (if preferred shares, specify issuance terms such as dividend rate): Equity in Formosa Daicel Fine Chemicals Co., Ltd.

2. Date on which the fact occurred: 115/8/12 ~ 115/8/12

3. Board approval date: August 12, 2026 (Minguo Year 115)

4. Other approval dates: Not applicable

5. Transaction quantity, unit price, and total transaction amount: Transaction quantity: 40,000,000 shares Unit price: NT$10 per share Total transaction amount: NT$400,000,000

6. Counterparty and its relationship with the company (if the counterparty is an individual and not a related party, name disclosure may be omitted): Formosa Daicel Fine Chemicals Co., Ltd. A newly established joint venture company co-invested by our company and DIC Corporation, Japan

7. If the counterparty is a related party, disclose the reason for selecting them, previous owner, relationships among previous owner, company, and counterparty, transfer date, and amount: Not applicable

8. If the ownership of the subject asset was held by a related party of the company within the past five years, disclose the related party’s acquisition and disposal date, price, and relationship with the company at that time: Not applicable

9. Matters regarding the disposal of receivables (including types of collateral attached to disposed receivables; if receivables from related parties are involved, disclose names and book value): Not applicable

10. Gain (or loss) from disposal (not applicable for acquisition of securities) (if previously deferred, explain recognition status): Not applicable

11. Delivery or payment terms (payment period and amount), contractual restrictions, and other important agreements: Delivery or payment terms: Based on the funding needs of the new company Contractual restrictions and other important agreements: None

12. Decision method for the transaction, reference basis for pricing, and decision-making body: Decision method and pricing basis: Based on original equity acquisition Decision-making body: Board of Directors of our company

13. Net asset value per share of the securities-issuing company being acquired or disposed: Not applicable

14. Cumulative number, amount, ownership percentage, and rights restriction status (e.g., pledge) of the securities involved in this transaction (including this transaction) held to date: Cumulative quantity: 40,000,000 shares Amount: NT$400,000,000 Ownership percentage: 50% Rights restriction status: None

15. Proportion of securities investments (including this transaction) listed under Article 3 of the 'Asset Acquisition and Disposal Rules for Publicly Issued Companies' to the total assets and equity attributable to parent owners in the company’s latest financial statements, and the working capital amount in the latest financial statements (Note 2): Proportion to total assets: 120.50% Proportion to equity: 109.54% Working capital amount: NT$72,006,246 thousand

16. Broker and brokerage fees: None

17. Specific purpose or use of acquiring or disposing of securities: Long-term investment

18. Opinions of dissenting directors regarding this transaction: None

19. Whether this transaction is a related-party transaction: No

20. Date of supervisor approval or audit committee consent: August 12, 2026 (Minguo Year 115)

21. Whether the accountant issued a non-reasonableness opinion on this transaction: Not applicable

22. Name of accounting firm: Not applicable

23. Name of accountant: Not applicable

24. Accountant license number: Not applicable

25. Whether it involves changes in business model: No

26. Explanation of business model change: Not applicable

27. Transaction status with the counterparty over the past year and expected future one year: Not applicable

28. Source of funds: Not applicable

29. Previous date of major information announcement on the same event: Not applicable

30. Other explanatory matters: The board of directors of our company has approved the establishment of a joint venture with DIC Corporation, Japan. The initial paid-in capital of the company is NT$800 million, with both parties holding 50% equity respectively.