Prior research has been contradictory on the relationship between financial and environmental performance. There are both theoretical and empirical reasons for this lack of consensus. Complying with environmental regulation is costly and thus might hurt a firm's bottom line. On the other hand, a firm that is efficient at pollution control might also be efficient at production. Moreover, a firm that does well financially can afford to spend more of its resources on cleaner technologies. Among the reasons for the past discrepancy in empirical findings is the lack of objective criteria to evaluate environmental performance.
Some authors have looked at subjective rankings by public interest groups, others have examined pollution control expenditures across industries, while others have compared the market returns of socially conscious mutual funds to overall market trends. This study reports on a new objective data set detailing the environmental performance of the Standard and Poor's 500 companies. We construct two industry-balanced portfolios and compare both accounting and market returns of the "high polluter" to the "low polluter" portfolio. Overall, we find either no "penalty" for investing in the "green" portfolio, or a positive return from green investing. We also examine the stock market reaction to new information on the environmental performance of individual firms, and provide a preliminary analysis of which comes first good financial performance or good environmental performance.