UMC Announces Disposal of Novatek Microelectronics Corp. Securities

1. Name and nature of the subject matter (for preferred shares, specify issuance terms such as dividend rate): Common shares of Novatek Microelectronics Corp.

2. Date on which the fact occurred: June 23, 2026 ~ June 23, 2026

3. Board approval date: Not applicable

4. Other approval dates: Approval level: Not applicable June 23, 2026

5. Transaction quantity, unit price, and total transaction amount: Number of units: 3,593,875 shares Unit price: NT$479.8 per share Total amount: NT$1,724,341,225

6. Counterparty and its relationship with the company (if the counterparty is a natural person and not a related party, name disclosure may be omitted): Conversion request by convertible bondholders.

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

8. If the owner of the subject asset was 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 the time: Not applicable

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

10. Gain (or loss) from disposal (not applicable for acquisition of securities; for deferred gains, provide a table showing recognition): Impact on retained earnings: NT$1,351,166,627 (no impact on profit or loss)

11. Delivery or payment terms (including payment periods and amounts), contractual restrictions, and other important agreements: Convertible bondholders converted into Novatek common shares. Contractual restrictions: None Other important agreements: None

12. Method of transaction decision, basis for price determination, and decision-making unit: Transaction decision method: In accordance with the prospectus Basis for price determination: Conversion based on exchange price

13. Net asset value per share of the securities-issuing company: NT$118.20

14. Cumulative number, amount, ownership percentage, and rights restrictions (e.g., pledge status) of the securities held (including this transaction) to date: Quantity: 5,279,150 shares Amount: NT$2,486,891,329 Ownership percentage: 0.87% Rights restrictions: None

15. Ratio of securities investments (including this transaction) under Article 3 of the “Regulations Governing Acquisitions and Disposals of Assets by Publicly Issued Companies” to total assets and equity attributable to owners of the parent in the company’s latest financial statements, and the amount of working capital in the latest financial report: Total asset ratio: 41.40% Equity ratio: 56.67% Working capital in latest financial report: NT$44,980,640 thousand

16. Broker and brokerage fees: Broker: None Brokerage fees: None

17. Specific purpose or use of the acquisition or disposal of securities: Conversion of exchangeable bonds

18. Dissenting directors’ opinions on this transaction: Not applicable

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

20. Date of supervisor approval or audit committee consent: Not applicable

21. Whether auditors issued an adverse reasonableness opinion on this transaction: Not applicable

22. Name of accounting firm: Not applicable

23. Name of auditor: Not applicable

24. Auditor license number: Not applicable

25. Whether it involves a change in business model: No

26. Explanation of business model change: Not applicable

27. Transaction status with the counterparty in the past year and expected in the next year: Not applicable

28. Source of funds: Not applicable

29. Previous date of material information disclosure regarding the same event: Not applicable

30. Other explanatory matters: None