This paper investigates whether institutional investors trade profitably around earnings announcements. We argue that institutions have informational advantage before negative earnings surprises but not before positive earnings surprises since the positive news tend to leak to market before the event. Using unique Korean data over the period of 2001-2010, we find that trading volume decreases only before the negative event due to information asymmetry among investors. We also find that institutions sell the stock before the negative earnings surprises but individual investors do not anticipate the bad news, and that trade imbalance by the institutions is positively related to the announcement abnormal returns of the negative events. The evidence is consistent with our conjecture that the domestic institutions exploit their superior information around the negative earnings surprises. Our results also show that foreign investors do not have any informational advantage compared to local investors on the upcoming earnings news.