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): Ordinary shares of Novatek Microelectronics Corp.

2. Date of occurrence: 2026/06/22 ~ 2026/06/22

3. Board approval date: Not applicable

4. Other approval dates: Approval level: Not applicable June 22, 2026

5. Transaction quantity, unit price, and total transaction amount: Number of units: 3,500,832 shares Unit price: TWD 479.8 per share Total amount: TWD 1,679,699,193

6. Counterparty and its relationship with the company (if the counterparty is an individual and not a related party, name disclosure may be omitted): Exchangeable bondholders applied for conversion.

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

8. If the owner of the subject securities 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 disposal of receivables (including types of collateral, and if receivables from related parties, disclose names and book value): Not applicable

10. Gain (or loss) from disposal (not applicable for acquisition of securities) (if previously deferred, explain recognition): Impact on retained earnings: TWD 1,396,704,971 (no impact on profit or loss)

11. Delivery or payment terms (including payment period and amount), contractual restrictions, and other important agreements: Exchangeable bondholders converted into Novatek ordinary shares. Contractual restrictions: None Other important agreements: None

12. Transaction decision method, pricing reference basis, and decision-making unit: Transaction decision method: As per the prospectus Pricing reference basis: Conversion based on exchange price

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

14. Cumulative holdings of these securities (including this transaction) to date in quantity, amount, ownership percentage, and any rights restrictions (e.g., pledge status): Quantity: 8,873,025 shares Amount: TWD 4,211,232,554 Ownership percentage: 1.46% Rights restrictions: None

15. Ratio of securities investments (including this transaction) under Article 3 of the “Asset Acquisition and Disposal Rules for Publicly Issued Companies” to total assets and equity attributable to parent owners in the latest financial statements, and the amount of operating capital in the latest financial report: Total asset ratio: 41.71% Equity ratio: 57.09% Latest financial report operating capital: TWD 44,980,640 thousand

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

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

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

19. Is this transaction a related-party transaction? No

20. Date of auditor’s confirmation or audit committee approval: Not applicable

21. Did the accountant issue a non-reasonableness opinion on this transaction? Not applicable

22. Name of accounting firm: Not applicable

23. Name of accountant: Not applicable

24. Accountant’s license number: Not applicable

25. Does this involve a change in business model? No

26. Explanation of business model change: Not applicable

27. Transaction history 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 on the same event: Not applicable

30. Other explanatory matters: None