Who's Informed? An Analysis of Stock Ownership and Informed Trading

This paper examines the relationship between ownership structure and informed trading. We attempt to reconcile some puzzling results in recent empirical literature about the impact of ownership on informed trading using a comprehensive set of proxies for informed trading and a recent sample of firms from three U.S equity exchanges. As proxies for informed trading, we use four measures: (1) The relative spread, (2) the adverse selection component of the spread, constructed as in Huang and Stoll (1997), (3) the price impact of a trade, following Foster and Viswanathan (1993) and Hasbrouck (1991), and (4) the probability of informed trading constructed as in Easley, Kiefer, O'Hara and Paperman (1996). We find strong evidence of a cross-sectional relationship between our measures of informed trading and ownership by institutions and insiders. Our results are robust to a variety of estimation techniques, control variables, and proxies for informed trading. Overall, our results suggest that individual investors are less informed relative to institutions and insiders. These findings are consistent with economies of scale in information acquisition and aggregation, and with recent research that indicates that market makers move prices in response to trades by institutions.