2338 Photomask Corporation Announces Key Executive Changes

Disclosure Date: June 27, 2026 Statement Date: June 26, 2026 Statement Time: 13:59:05 Company Code: 2338 Company Name: Photomask Corporation

Subject: Announcement of Changes in Accounting Officer and Spokesperson

Applicable Clause: Clause 8 Event Date: June 26, 2026

Details:

1. Position Type (Select from: Spokesperson, Acting Spokesperson, Key Operational Executive (e.g., CEO, COO, CMO, CSO), Financial Officer, Accounting Officer, Corporate Governance Officer, Chief Information Security Officer, R&D Officer, Internal Audit Officer, Litigation/Non-litigation Agent): Accounting Officer, Spokesperson, Chief Financial Officer

2. Effective Date of Change: June 26, 2026

3. Former Executive Name, Title, and Background: Lin Shu-Hua: Accounting Officer and Financial Officer, Photomask Corporation (Taiwan) Yang Yi-Ting: Spokesperson and Chief Financial Officer, Photomask Corporation (Taiwan)

4. New Executive Name, Title, and Background: Ruan Zhao-Hui: Accounting Officer, Photomask Corporation (Taiwan) / Special Assistant, Photomask Corporation (Taiwan) Chen Li-Dun: Spokesperson, Photomask Corporation (Taiwan) / General Manager, Photomask Corporation (Taiwan)

5. Nature of Change (e.g., Resignation, Job Reassignment, Severance, Retirement, Death, New Appointment, Dismissal): Job Reassignment

6. Reason for Change: Job Reassignment

7. Effective Date: June 26, 2026

8. Additional Notes: The title of Chief Financial Officer has been adjusted to Senior Vice President.