ISO order imbalances and individual stock returns

I examine the relation between intermarket sweep order (ISO) order imbalances and the daily returns of individual stocks. First, I show that ISO order imbalances are positively related to contemporaneous returns. Second, I find that price pressures emanating from ISO imbalances are persistent and predict cumulative abnormal returns up to 2 months. The predictive power of ISO order imbalances on contemporaneous and future abnormal returns is strongest for firms in the smallest firm size quintile. Finally, I analyze herding among ISO order imbalances and find strong commonality. My results indicate that ISOs contribute to both short- and long-term return formation.