Subsidiary Announces Change of Auditors

Date of Announcement: June 25, 2026 Company Name: ASE Holding Corporation (3711)

[Announcement Details] ASE Group announced that its subsidiary, Universal Scientific Industrial (France), has resolved to change its auditor.

1. Board Resolution Date (Event Date): June 25, 2026 2. Former Auditing Firm: ERNST & YOUNG et Autres 3. Former Signing Auditor Name 1: Sebastien Vouaux 4. Former Signing Auditor Name 2: None 5. New Auditing Firm: DBA Expertise Comptable, Audit et Conseil 6. New Signing Auditor Name 1: Laurent Echauzier 7. New Signing Auditor Name 2: None 8. Reason for Change: To better align with the company's adjusted operational development and internal management needs 9. Nature of Termination: Company-initiated termination of appointment 10. Date of Notification of Termination: June 25, 2026 11. Whether the past two years' financial reports have undergone auditor adjustments or received significant internal control improvement recommendations: No 12. Whether the company disagreed with any of the above adjustments or recommendations: Not applicable 13. Whether the company consulted the successor auditor on the former auditor’s adjustments or recommendations prior to formal appointment: Not applicable 14. Whether the company authorized the former auditor to fully respond to reasonable inquiries from the successor auditor: Yes 15. Other Matters: Financial reports from 2026 onward will be audited by the newly appointed auditing firm.