This paper documents strong evidence for behavioral biases among Chicago Board of Trade proprietary traders and investigates the effect these biases have on prices. Our traders appear highly loss‐averse, regularly assuming above‐average afternoon risk to recover from morning losses. This behavior has important short‐term consequences for afternoon prices, as losing traders actively purchase contracts at higher prices and sell contracts at lower prices than those that prevailed previously. However, the market appears to distinguish these risk‐seeking trades from informed trading. Prices set by loss‐averse traders are reversed significantly more quickly than those set by unbiased traders.

A mutual fund manager is more likely to buy (or sell) a particular stock in any quarter if other managers in the same city are buying (or selling) that same stock. This pattern shows up even when the fund manager and the stock in question are located far apart, so it is distinct from anything having to do with local preference. The evidence can be interpreted in terms of an epidemic model in which investors spread information about stocks to one another by word of mouth.

We develop a performance evaluation approach in which a fund manager's skill is judged by the extent to which the manager's investment decisions resemble the decisions of managers with distinguished performance records. The proposed performance measures use historical returns and holdings of many funds to evaluate the performance of a single fund. Simulations demonstrate that our measures are particularly useful in ranking managers. In an application that relies on such ranking, our measures reveal strong predictability in the returns of U.S. equity funds. Our measures provide information about future fund returns that is not contained in the standard measures.

Motivated by extant finance theory predicting that insider trading crowds out private information acquisition by outsiders, we use data for 100 countries for the years 1987–2000 to study whether analyst following in a country increases following restriction of insider trading activities. We document that analyst following increases after initial enforcement of insider trading laws. This increase is concentrated in emerging market countries, but is smaller if the country has previously liberalized its capital market. We also find that analyst following responds less intensely to initial enforcement when a country has a preexisting portfolio of strong investor protections.