Stakeholder Communication

Four types of surveys were distributed

The company aligns with leading international sustainability disclosure standards, incorporates diverse stakeholder expectations, and applies the double materiality principle to identify and prioritize material sustainability topics.
22 ESG topics were identified and evaluated across the two core dimensions of impact materiality and financial materiality. Feedback and comments from stakeholders were collected through four online surveys. Concurrently, managers at all levels proceeded to assess the levels of impact, while department heads worked together with the sustainability team on sustainability impact identification. For the assessment on financial materiality, all business units proactively identified relevant risks and opportunities. The company’s CFO and CAO will then review and validate these risks and opportunities to determine the financial materiality of each topic.

Impact Materiality

We have designed two questionnaires - “Stakeholder Concern Regarding Sustainability Topics” and “External Sustainability Impacts,” to evaluate impact materiality.

3,407 stakeholders participated in the Stakeholder Concern Survey

Stakeholder Concerns: Stakeholder input plays a key role in ASEH’s material topic identification process, serving as a vital communication channel between the company and our external partners. In 2025, in accordance with the AA1000 Stakeholder Engagement Standard (AA1000 SES), we have systematically evaluated the significance and priority of stakeholder groups across five key criteria: Dependency, Responsibility, Tension (Concern), Influence, and Diverse Perspectives. A total of 21 managers and employees participated in this assessment process. Ten stakeholder groups were identified as the primary focus for subsequent communication and engagement efforts. This year, “academic institutions” was included as a new stakeholder category.
A total of 3,407 responses was collected from the survey. The respondents comprised: employees (2,049), suppliers and contractors (783), community representatives (186), academic institutions (115), customers (90), NGOs (40), industry unions and associations (33), shareholders (30), media representatives (29), and government agencies (52). The survey sampling methodology was structured to ensure diversity and comprehensive representation, and to adequately reflect stakeholder perspectives across different sectors. The ESG topics of concern ranked in the top 33% were: Business Ethics, Regulatory Compliance, Risk and Crisis Management, Data Privacy, Occupational Health and Safety, Human Rights Management, Energy Management, Waste and Circular Reuse, and Information Security Management. These material topics reflect external expectations of ASEH’s corporate responsibilities, and serve as important references for the company in formulating its sustainability development strategies and targets.

10 Major Sustainability Impacts

Sustainability Impact: Methodologies developed by key organizations such as the Value Balancing Alliance (VBA), Harvard Business School’s Impact-Weighted Accounts Initiative (IWAI), and the London Benchmarking Group (LBG) were used to help identify a total of 22 external sustainability impact indicators relevant to our operations, including 5 economic impacts, 6 environmental impacts, and 11 social impacts. During the impact identification phase, 46 department heads and core sustainability team members participated in identifying significant external impacts relevant to ASEH’s operations: positive vs. negative impacts, actual vs. potential impacts, severity (scale), scope, irremediability, likelihood of occurrence, and regulatory compliance. 10 external impacts significantly relevant to the company were identified. Participants also leveraged their own experience to assess the relevance of each ESG topic to the identified external impacts. The results indicated that Sustainable Supply Chain, Sustainable Manufacturing, and Waste and Circular Reuse were the major ESG topics contributing to the identified external impacts.

Financial Materiality

The “Organizational and Operational Impacts” and the “IFRS S1/S2 Readiness Assessment” surveys were used as the basis for assessing impact materiality.

183 executives and members of the Corporate Sustainability Committee participated in the Organizational Operational Impact Survey

Organizational and Operational Impacts: A total of 183 executives and members of the Corporate Sustainability Committee participated in the assessment of the impact of each ESG topic across four key operational factors: Revenue Generation, Risk Exposure, Customer Satisfaction, and Employee Engagement. The results indicated that the ESG topics with the most significant operational impact were Regulatory Compliance, Customer Relationship Management, Risk and Crisis Management, and Data Privacy. The systematic identification of the impact of each ESG issue on core business operations allow us to enhance resource allocation, develop more targeted ESG strategies, and further strengthen the integration of sustainability into company operations.

5 Major Risks and Opportunities

IFRS S1/S2 Readiness Assessment: After defining materiality thresholds, five major sustainability-related risks and opportunities with significant financial impacts on the company were identified: Supplier Management, Human Capital, Climate Transition, Physical Climate-Related Risks, and Water Transition. These findings were subsequently submitted to senior management for validation. The corresponding ESG topics carrying the highest financial impacts include: Climate Strategy, Energy Management, Sustainable Supply Chain, Talent Attraction and Retention, and Talent Development.

ASEH has established a multi-layered evaluation framework to ensure the objectivity of its materiality assessment results. The methodology incorporates the results of both financial materiality and impact materiality assessments, closely aligning sustainability issues with our long-term development strategy. Financial materiality is assessed based on operational impact evaluations and IFRS S1/S2 assessments, while impact materiality is evaluated through stakeholder surveys and sustainable development impact assessments. In addition to the survey results, other considerations including the company’s sustainability development roadmap, long-term sustainability targets, and the linking of executive compensation to ESG metrics, were also incorporated into the assessment process. Material topics are selected based on the following criteria:

Three main screening criteria

• Criteria 1: Meeting the financial and impact materiality threshold in at least two of the four materiality surveys

• Criteria 2: Alignment with the company’s long-term sustainability targets

• Criteria 3: Linking executive compensation to ESG metrics

Topics satisfying at least two of these criteria were prioritized as material. To finalize the material topics for the 2025 Sustainability Report, we convened a sustainability review meeting, and conducted indepth discussions with consultants and senior management. This process ensured that the report aligns with ASEH’s overall sustainability strategy while proactively addressing stakeholder concerns.

18 Material topics

Following a structured evaluation process and defined selection criteria, the company identified and prioritized 18 material sustainability topics in the following sequence:

1. Climate Strategy
2. Sustainable Supply Chain
3. Water Resource Management
4. Energy Management
5. Regulatory Compliance
6. Waste and Circular Reuse
7. Occupational Health and Safety
8. Talent Attraction and Retention
9. Business Ethics
10. Sustainable Manufacturing
11. Customer Relationship Management
12. Information Security Management
13. Talent Development
14. Social Engagement
15. Human Rights Management
16. Innovation Management
17. Biodiversity
18. Diversity and Inclusion

4 Major Impact Stages, Corresponding to 25 Topics Topics

These issues were formally presented to the Board of Directors and validated based on their relevance and impact across four key stages of the ESG value chain: upstream procurement, manufacturing facilities, downstream impact, and external value chain stages.

Each issue was subsequently mapped across 20 GRI Topics and 5 ASE-specific topics, with disclosures adhering to the principles of double materiality. The report outlines the impact scope, management approach, and associated risks for each material issue. Non-material issues were also disclosed in the sustainability report to ensure transparency in stakeholder communication.

The ASE Holdings Corporate Sustainability and Information Security Committee (CSISC) conducts annual reviews to track milestones and oversee each business units’ progress. In addition, the internal sustainability committees within each of our three major subsidiaries regularly convene to closely monitor the progress of these goals and track emerging sustainability trends.

48 Long-term Goals

To enhance the company’s sustainability impact, we have established clear commitments for each material issue and set 48 long-term sustainability goals for 2035. These goals are being progressively implemented through various projects and initiatives across our global sites.

4 Dedicated sustainability committees

• ASE Holdings Corporate Sustainability and Information Security Committee (CSISC)

• ASE Corporate Sustainability Committee

• SPIL Sustainability Committee

• USI Sustainability Committee