There is a large and diverse body of evidence that people condition their behavior on the characteristics of others. If type is visible then one agent seeing another with whom they are interacting, or observing some other close proxy for type, can affect outcomes. We explore the economics of...

We provide detailed empirical evidence of a direct effect of air pollution on the efficient operation of the New York Stock Exchange, linking short-term variations in fine particulate matter (PM2.5) in Manhattan to movements in the S&P 500. The effects are substantial – a one standard...