We show that the positive relation between institutional ownership and future stock returns documented in Gompers and Metrick (2001) is driven by shortterm institutions. Furthermore, short-term institutions' trading forecasts future stock returns. This predictability does not reverse in the long run and is stronger for small and growth stocks. Short-term institutions' trading is also positively related to future earnings surprises. By contrast, long-term institutions' trading does not forecast future returns, nor is it related to future earnings news. Our results are consistent with the view that short-term institutions are better informed and they trade actively to exploit their informational advantage. (JEL G12, G14, G20) This article examines the relation between institutions' investment horizons and their informational roles in the stock market. Although a large body of literature has studied the behavior of institutional trading and its impact on asset prices and returns, 1 the informational role of institutional investors remains an open question. Gompers and Metrick (2001) document a positive relation between institutional ownership and future stock returns. However, they attribute this relation to temporal demand shocks rather than institutions' informational advantage. Nofsinger and Sias (1999) find that changes in institutional ownership forecast next year's returns, suggesting that institutional trading contains information about future returns. In contrast, Cai and Zheng (2004)
find that institutional tradingWe thank