Disentangling the causal impact of media reporting from the impact of the events being reported is challenging. We solve this problem by comparing the behaviors of investors with access to different media coverage of the same information event. We use zip codes to identify 19 mutually exclusive trading regions corresponding with large U.S. cities. For all earnings announcements of S&P 500 Index firms, we find that local media coverage strongly predicts local trading, after controlling for earnings, investor, and newspaper characteristics. Moreover, local trading is strongly related to the timing of local reporting, a particular challenge to nonmedia explanations.

Major League Baseball umpires express their racial/ethnic prefer ences when they evaluate pitchers. Strikes are called less often if the umpire and pitcher do not match race/ethnicity, but mainly where there is little scrutiny of umpires. Pitchers understand the incentives and throw pitches that allow umpires less subjective judgment (e.g., fastballs over home plate) when they anticipate bias. These direct and indirect effects bias performance measures of minorities downward. The results suggest how discrimination alters discriminated groups' behavior generally. They imply that biases in measured productivity must be accounted for in generating measures of wage discrimination.