3703 Hsin Chong | Subsidiary Announces Sale of Real Estate and Parking Spaces in Zhubei, Hsinchu County to Related Party

Disclosure Date: June 23, 2026 Statement Date: June 22, 2026 Statement Time: 17:51:45 Company Code: 3703 Company Name: Hsin Chong Subject: Announcement by Subsidiary Mainland Construction Co., Ltd. Regarding Sale of Real Estate and Parking Spaces to Related Party Applicable Clause: Item 20 Factual Date: June 22, 2026

1. Name and Nature of the Subject Property (e.g., Land in Section X, Subsection X, North District, Taichung City): Residential units and parking spaces in the 'Shih Hua' project, Zhubei City, Hsinchu County

2. Factual Date: June 22, 2026 ~ June 22, 2026

3. Board Approval Date: June 22, 2026

4. Other Approval Dates: Not applicable

5. Quantity of Units (e.g., XX square meters, equivalent to XX ping), Unit Price, and Total Transaction Value: Transaction Quantity: 2 residential units (approximately 41.20 ping each) and 3 parking spaces (approximately 9.58 ping each) Total Transaction Value: NT$77.66 million

6. Counterparty and Its Relationship with the Company (If the counterparty is an individual and not a related party of the company, name disclosure may be omitted): Wang Wei-Fan, Deputy General Manager of the Legal Department, Hsin Chong Investment Holding Co., Ltd.

7. If the counterparty is a related party, state the reason for selecting the related party, the previous transferor, the relationship between the previous transferor, the company, and the counterparty, the previous transfer date, and transfer amount: (1) Reason for selecting a related party as the counterparty: This is a publicly sold project by Mainland Construction Co., Ltd., constituting a regular sales transaction with no restrictions on buyers. (2) Previous transferor, relationship with the company and counterparty, transfer date, and amount: Not applicable

8. If the property owner within the past five years was a related party of the company, disclose the acquisition and disposal dates, price, and relationship with the company at the time: Not applicable

9. Estimated disposal gain (or loss) (not applicable for asset acquisition; deferred gains must be detailed): Estimated disposal profit margin is approximately 13%.

10. Delivery or payment terms (including payment schedule and amounts), contractual restrictions, and other important agreements: Delivery or payment terms: As per contract agreement. Contractual restrictions: None Other important agreements: None

11. Decision method for the transaction (e.g., bidding, price comparison, negotiation), reference basis for pricing, and decision-making unit: Decision method: Negotiated pricing Pricing reference basis: Market conditions and group employee home purchase guidelines Decision-making unit: Board approval

12. Name of professional appraiser firm or company and appraisal value: Not applicable

13. Name of professional appraiser: Not applicable

14. Professional appraiser license number: Not applicable

15. Whether the appraisal report is for a limited, specific, or special price: No or not applicable

16. Whether an appraisal report has not yet been obtained: No or not applicable

17. Reason for not obtaining an appraisal report: Not applicable

18. If there is a significant difference in appraisal results, explain the reason and provide auditor's opinion: Not applicable

19. Auditor firm name: Not applicable

20. Auditor name: Not applicable

21. Auditor license number: Not applicable

22. Broker and brokerage fees: Not applicable

23. Specific purpose or use of the acquisition or disposal: Core business sales to increase revenue and achieve project-level profitability.

24. Opinions of directors who objected to the transaction: None

25. Whether this transaction is a related-party transaction: Yes

26. Date of supervisor approval or audit committee consent: June 22, 2026

27. Whether the transaction involves acquiring real estate or right-of-use assets from a related party: No

28. Valuation under Article 16 of the 'Asset Acquisition and Disposal Rules for Publicly Issued Companies': Not applicable

29. Valuation under Article 17 of the same rules if the valuation in the previous item is lower than the transaction price: Not applicable

30. Previous date of material information disclosure for the same event: Not applicable

31. Other explanatory matters: None