Aggregate short selling, commonality, and stock market returns

Using a comprehensive data set of short-sale transactions, we find strong evidence of commonality in daily shorting flows of individual stocks. More importantly, we find that aggregate shorting forecasts market returns. A one standard deviation increase in daily aggregate shorting is associated with a decrease in market excess return by up to 36bps over the following 10 trading days (9% annualized). In addition, we find modest evidence that short sellers are informed about future aggregate earnings news, macroeconomic news, and investor sentiment. Overall, our results are consistent with short sellers possessing superior short-term market-wide information.