When rules become clear: capital market reactions to Hong Kong's Stablecoin Ordinance

This study examines capital market reactions to the gazettal of Hong Kong's Stablecoin Ordinance. This event provides a clearly identifiable informational signal that resolves regulatory uncertainty. It is the first dedicated stablecoin legislation in a major global financial center. We integrate multi-factor asset pricing models with an event study framework to assess the Ordinance's impact on A-share concept stocks and its cross-border spillovers across 13 global markets. The results show that the market interpreted the enactment as a positive institutional development. The event generated significant cumulative abnormal returns. These returns are robust across four pricing benchmarks and survive placebo and matched-sample tests. The valuation gains are not uniform. They propagate along the industry chain. The largest premia go to firms most directly involved in compliance infrastructure. ChiNext-listed firms and smaller firms exhibit greater price elasticity. Cross-country patterns suggest regional asymmetry, with Asia-Pacific markets showing relatively more positive reactions than European markets. The US market exhibits a reversal from negative to positive post-event returns, consistent with a conjectural time-zone explanation, though alternative interpretations remain possible. European markets, already under the MiCA framework, show little response. By extending event study methodology to digital finance regulation, this paper validates the positive market value of regulatory clarity. It also reveals the non-uniform transmission of institutional change, offering micro-level evidence for global governance coordination.