Voluntary ISSB ‐Aligned Disclosure and Firm Value: Evidence From Asia‐Pacific Capital Markets

ABSTRACT

This study examines whether voluntary adoption of International Sustainability Standards Board (ISSB)‐aligned climate disclosure is associated with firm value among Asia‐Pacific listed firms. Using a hand‐collected panel of 490 firm‐year observations across seven economies from 2018 to 2024, the study applies difference‐in‐differences and two‐way fixed effects models following the release of IFRS S1 and IFRS S2 exposure drafts in 2022. The findings indicate that firms voluntarily adopting ISSB‐aligned disclosure tend to exhibit higher Tobin's Q and stronger operational performance measured through return on assets (ROA). The positive association is stronger in countries characterized by more mature ESG governance systems, suggesting that institutional context influences disclosure credibility and investor response. The study contributes early empirical evidence on the market relevance of structured climate‐related disclosure and highlights the growing importance of sustainability governance within Asia‐Pacific capital markets.