2323 CMC

Release Date: June 23, 2026 Statement Date: June 22, 2026 Statement Time: 17:51:19 Company Code: 2323 Company Name: CMC Subject: Announcement of Disposal of Marketable Securities Applicable Clause: Item 20 Date of Event: June 22, 2026

1. Security Name: MediaTek Common Stock

2. Transaction Date: June 10, 2026 – June 22, 2026

3. Board Approval Date: Not applicable

4. Other Approval Date: Approval Level: Approved by Chairman June 22, 2026 (R.O.C. Year 115)

5. Transaction Quantity, Unit Price, and Total Amount: Quantity (in thousands of shares): 72 Unit Price (NT$): 4,467.90 Total Transaction Amount (NT$): 321,689,092

6. Gain (or Loss) on Disposal (not applicable for acquisition): Gain on Disposal: NT$6,728,103

7. Relationship with the Target Company: None

8. Cumulative Holdings of the Security (including this transaction) to Date – Quantity, Value, Ownership Percentage, and Restricted Rights (e.g., Pledge Status): Remaining Holdings: 110,000 shares, Value: NT$482,384,158 Ownership Percentage: 0.007%, Restricted Rights: None

9. Proportion of Marketable Securities Investment (including this transaction) under Paragraph 3 of the “Asset Acquisition and Disposal Rules for Publicly Issued Companies” to Total Assets and Equity Attributable to Owners of Parent in the Company’s Latest Financial Statements, and the Amount of Working Capital in the Latest Financial Statements: Percentage of Total Assets: 82.21% Percentage of Equity Attributable to Owners of Parent: 118.07% Working Capital Amount: NT$8,285,327 thousand

10. Specific Purpose of Acquisition or Disposal: Investment portfolio adjustment

11. Dissenting Director’s Opinion on This Transaction: None

12. Whether This Transaction is a Related-Party Transaction: No

13. Counterparty and Relationship with the Company: Not applicable

14. Date of Supervisor Approval or Audit Committee Consent: Not applicable

15. Previous Date of Material Information Disclosure on the Same Event: Not applicable

16. Other Explanatory Matters: On March 31, 2026, authorized traders were granted permission to conduct securities transactions in the centralized market during the second quarter of 2026.