[ASE Technology Holding] Subsidiary SPIL Announces Acquisition of Plant Engineering Services

1. Type of contract: Plant engineering 2. Date of occurrence: June 10, 2026 - June 11, 2026 3. Date of board of directors approval: N/A 4. Date of other approval: Approval level: General Manager June 11, 2026 5. Counterparty to the contract and relationship to the Company: Lee Ming Construction Co., Ltd. Relationship with the Company: None 6. Major content of the contract (including total contract amount, anticipated investment, and contract period), restrictive covenants, and other important terms: Total amount: NTD 759,000,000 Contract period: June 10, 2026 to December 31, 2026 Restrictive covenants and other important terms: None 7. Name of professional appraisal firm or company and its appraisal result: N/A 8. Name of real estate appraiser: N/A 9. Practice certificate number of real estate appraiser: N/A 10. Specific purpose of the acquisition: For production and operation use 11. Any dissenting opinions of directors to the present transaction: None 12. Is this a related party transaction: No 13. Date of recognition by supervisors or approval by audit committee: N/A 14. Whether the appraisal report indicates a limited price, specific price, or special price: No or N/A 15. Whether an appraisal report has not yet been obtained: No or N/A 16. Reason for not yet obtaining an appraisal report: N/A 17. Reason for any significant discrepancy with the appraisal result and CPA opinion: N/A 18. Name of CPA firm: N/A 19. Name of CPA: N/A 20. Practice certificate number of CPA: N/A 21. Date of previous material information announcement for the same transaction: N/A 22. Other matters to be specified: None