From ESG Strength to Reputational Risk: Evidence from Environmental Penalties in S&P 500 Firms

Environmental sanctions can generate financial consequences that extend well beyond the direct monetary cost of regulatory penalties, particularly when they conflict with firms’ established sustainability reputations. This study investigates how financial markets respond to environmental penalties and whether prior ESG performance shapes the magnitude of this response. Using a comprehensive sample of environmental violations involving S&P 500 companies over the 2000-2024 period, we combine a market-model event-study framework with parametric and non-parametric tests and regression analysis of cumulative abnormal returns. The results show that environmental penalties are followed by negative abnormal stock returns, with the adverse market response becoming more pronounced and persistent over longer event windows. More importantly, the relationship between ESG performance and market reactions changes substantially after the Paris Agreement. From 2016 onward, firms characterized by stronger ESG profiles experience more negative stock-market reactions when environmental sanctions occur. Rather than providing reputational protection, high ESG credentials may therefore increase firms’ exposure to market losses when observed environmental behavior conflicts with previous sustainability signals. We interpret this pattern as a “hypocrisy penalty”, whereby investors react more strongly to misconduct when it represents a breach of expectations created by a firm’s sustainability profile. The findings suggest that the financial implications of environmental misconduct increasingly depend not only on the violation itself but also on the consistency between corporate sustainability commitments and actual behavior. Overall, the study highlights the growing relevance of ESG credibility and perceived authenticity for investor assessment and capital-market valuation.