[CMC] Announcement Regarding Disposal of Securities

1. Name of Security: ADATA common stock 2. Transaction Date: May 15, 2026 – May 21, 2026 3. Date Approved by Board of Directors: Not applicable 4. Other Authorization Date: Chairman approval, May 21, 2026 5. Quantity, unit price, and total transaction amount: Quantity 743,000 shares, unit price 409.82 TWD, total amount 304,498,360 TWD 6. Disposal Gain (or Loss): Disposal loss 19,277,319 TWD 7. Relationship with the company whose securities were traded: None 8. Accumulated holdings as of now (including this transaction): Balance 903,000 shares, amount 396,592,636 TWD, shareholding ratio 0.28%, restrictions: None 9. Investment in securities under the 'Regulations Governing the Acquisition and Disposal of Assets by Public Companies' (including this transaction) as a percentage of total assets and equity attributable to owners of the parent in the most recent financial statements, and working capital: Ratio to total assets 77.36%, ratio to equity attributable to owners of the parent 111.11%, working capital 8,285,327,000 TWD 10. Specific purpose of acquisition or disposal: Investment portfolio 11. Opinions of directors who dissented from this transaction: None 12. Whether this transaction is a related-party transaction: No 13. Transaction counterparty and its relationship with the company: Not applicable 14. Date of approval by supervisor or audit committee: Not applicable 15. Date of previous material information release regarding the same event: Not applicable 16. Other notes: Authorized traders were previously empowered on March 31, 2026, to conduct securities trading in the centralized market during the second quarter of 2026.