3711 ASE Holding: Subsidiary SPIL Announces Acquisition of Facility Engineering Project

Date of Announcement: July 7, 2026 Date of Statement: July 6, 2026 Time of Statement: 20:48:52 Company Code: 3711 Company Name: ASE Holding Subject: Announcement by subsidiary Silicon Precision Industries Co., Ltd. regarding acquisition of facility engineering project Applicable Clause: Clause 20 Date of Event: July 6, 2026

Details: 1. Type of Contract: Facility Engineering 2. Date of Event: November 13, 2025 ~ July 6, 2026 3. Board Approval Date: Not applicable 4. Other Approval Dates: Approval Level: Approved by President July 6, 2026 5. Contract Counterparty and Relationship with Company: Chuan Hong Air Conditioning System Service Co., Ltd. Relationship with Company: None 6. Main Contents of Contract (including total contract value, expected investment amount, contract start and end dates), Restrictive Clauses, and Other Important Agreements: Total Amount: TWD 611,747,607 Contract Period: November 13, 2025 to October 31, 2027 Restrictive Clauses and Other Important Agreements: None 7. Name of Professional Appraisal Firm or Company and Appraisal Result: Not applicable 8. Name of Real Estate Appraiser: Not applicable 9. License Number of Real Estate Appraiser: Not applicable 10. Specific Purpose of Acquisition: For production and operational use 11. Dissenting Director's Opinion on the Transaction: None 12. Is the Transaction a Related-Party Transaction: No 13. Date of Supervisor's Approval or Audit Committee's Consent: Not applicable 14. Is the Appraisal Report a Limited Price, Specific Price, or Special Price: No or Not applicable 15. Has the Appraisal Report Not Yet Been Obtained: No or Not applicable 16. Reason for Not Yet Obtaining the Appraisal Report: Not applicable 17. Reasons for Significant Differences in Appraisal Results and Auditor's Opinion: Not applicable 18. Name of Auditor's Firm: Not applicable 19. Name of Auditor: Not applicable 20. Auditor's License Number: Not applicable 21. Previous Date of Material Information Disclosure on the Same Event: Not applicable 22. Other Disclosures: None