Essays in capital markets

Abstract

(cont.) Slow information diffusion can cause return momentum. Institutions are thought to be more informed than individuals, and should eliminate return predictability. However, higher institutional ownership is associated with more momentum. Therefore, institutions either herd on returns or can have information before individuals. I find evidence of the latter. However, the effects are economically small, suggesting that aggregate data obscures differences between institutions. I divide institutions by trading aggressiveness. Aggressive institutions are more responsive to recent returns, and a strategy mimicking their trades generates even better performance. This confirms that some investors are more informed than others, but do not eliminate return predictability.

This thesis consists of three chapters, each about a separate aspect of how investors respond to information in equity markets. The first chapter concerns news and stock returns. Using a comprehensive database of headlines about individual companies, I examine monthly returns following public news. I compare them to stocks with similar returns, but no identifiable public news. There is a difference between the two sets. I find strong drift after bad news. Investors seem to react slowly to this information. I also find reversal after extreme price movements unaccompanied by public news. The separate patterns appear even after adjustments for risk exposure and other effects. They are, however, mainly seen in smaller, more illiquid stocks. These findings support some integrated theories of investor over- and underreaction. The second chapter is joint work with Richard Frankel and S. P. Kothari. Models based on psychology can explain momentum and reversal in stock returns, but may be overfitted to data. We examine a typical basis for these models, representativeness, in which individuals predict the future based on how closely past outcomes fit certain categories. We use accounting performance to mimic possible investor-defined categories for firm performance. We test the idea that investors predictably bias their expectations about future operations by using these categories. We find little evidence that the sequence or trend of past accounting performance is related to future returns, and is therefore unlikely to bias investor expectations. The third chapter concerns how informational advantage differs between institutional investors.