Are Green Bonds Associated with Shareholder Value? Market Reaction and Firm-Valuation Evidence from Thailand

Whether green-bond issuance is associated with shareholder value remains unclear in small, concentrated emerging markets, where signaling and information-asymmetry channels from developed-market studies may not operate the same way. This study examines short-term stock-market reactions and medium-term firm valuation associated with green-bond issuance among the full population of 20 eligible Thai listed issuers: 34 analytical issuance events from May 2019 to May 2026, and an annual panel of 20 firms observed from 2015 to 2025, comprising 220 repeated firm-year observations and 187 complete cases in the baseline regression. Event-study models find no statistically detectable average abnormal return around the issue date, robust across benchmark models and event windows; two-way fixed-effect panel regressions, likewise, find no statistically detectable average association with Tobin’s Q, with a confidence interval wide enough to admit economically meaningful effects in either direction. The matching and selection analyses remain inconclusive. The IV model has a weak first stage and is therefore reported only as a diagnostic. Because the design identifies within-firm variation among issuers, rather than a comparison with matched non-issuers, the results should be read as associations, rather than causal effects. The study provides census-based evidence that, in Thailand’s small and concentrated green-bond market, a green label may not yet carry detectable average value relevance for shareholders.