UMC Announces Disposal of Novatek Microelectronics Corp. Securities

Disclosure Date: June 23, 2026 Statement Date: June 22, 2026 Statement Time: 17:16:12 Company Code: 2303 Company Name: United Microelectronics Corporation (UMC) Subject: Announcement of Disposal of Securities in Novatek Microelectronics Corp. Applicable Clause: Clause 20 Factual Date: June 22, 2026

1. Name and Nature of the Asset (for preferred shares, specify dividend rate and other terms): Ordinary shares of Novatek Microelectronics Corp.

2. Factual Date: June 22, 2026 ~ June 22, 2026

3. Board Approval Date: Not applicable

4. Other Approval Dates: Approval Level: Not applicable June 22, 2026 (R.O.C. Year 115)

5. Transaction Quantity, Unit Price, and Total Amount: Number of Units: 3,500,832 shares Unit Price: NT$479.8 per share Total Amount: NT$1,679,699,193

6. Counterparty and Relationship with the Company (Name may be omitted if individual and not a related party): Exchangeable bondholders applied for conversion.

7. If counterparty is a related party, disclose reason for selection, prior transferor, relationships, transfer date, and amount: Not applicable

8. If asset owner was a related party within the past five years, disclose acquisition/disposal date, price, and relationship at the time: Not applicable

9. Matters related to disposal of receivables (including collateral types; if receivable from a related party, disclose name and book value): Not applicable

10. Gain (or loss) from disposal (not applicable for acquisition of securities; deferred gains to be explained): Impact on retained earnings: NT$1,396,704,971. (No impact on profit or loss)

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

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

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

14. Cumulative holdings of the securities involved (including this transaction) to date, including quantity, amount, ownership percentage, and restricted rights (e.g., pledge status): Quantity: 8,873,025 shares Amount: NT$4,211,232,554 Ownership percentage: 1.46% Rights restriction status: None

15. Ratio of cumulative securities investments under Article 3 of the "Asset Acquisition and Disposition Rules for Publicly Issued Companies" (including this transaction) to total assets and equity attributable to owners of parent in the latest financial statements, and the latest operating capital: Total asset ratio: 41.71% Equity ratio: 57.09% Latest financial report operating capital: NT$44,980,640,000

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

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

21. Whether accountants issued a non-reasonable 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 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 on the same event: Not applicable

30. Other explanatory matters: None