The Value Relevance of Nonfinancial Measures of Air Pollution in the Electric Utility Industry
研究1990年《清洁空气法》修正案第一阶段下，高污染电力企业的二氧化硫排放这一非财务指标与股票市场价值的关系，发现该指标平均导致股价下跌16%，且其价值相关性随法规出台和合规成本变化而波动。
This study examines the relation between the market value of equity and nonfinancial pollution measures (sulfur dioxide emissions) that capture firms' exposure to future environmental liabilities. I find that a nonfinancial pollution proxy is value-relevant for high-polluting electric utilities targeted for air pollution abatement by Phase One of the 1990 Clean Air Act Amendments (CAAA). On average, these utilities' exposure to (unbooked) future environmental liabilities decreased their mean 1990 share price by 16 percent. Moreover, the value relevance of the nonfinancial pollution proxy (1) increased in response to the passage of the stringent 1990 CAAA environmental legislation, and then (2) declined as the market subsequently reduced estimated compliance costs in response to changing economic and technological factors. Utilities not targeted by Phase One of the 1990 CAAA faced minimal exposure to future environmental liabilities and I find no significant relation between their pollution indicators and share prices. I also find that investors in the high-polluting rate-regulated utilities that were targeted by Phase One positively value a favorable regulatory climate.