We study the implications of learning in an environment where the true model of the world is a multivariate one, but where agents update only over the class of simple univariate models. If a particular simple model does a poor job of forecasting over a period of time, it is eventually discarded...

A number of theories have been proposed to explain the medium-term momentum in stock returns identified by Jegadeesh and Titman (1993). We test one such theory--based on the gradual-information-diffusion model of Hong and Stein (1997)--and establish three key results. First, once one moves past...

We develop a theory of stock-market crashes based on differences of opinion among investors. Because of short-sales constraints, bearish investors do not initially participate in the market and their information is not revealed in prices. However, if other, previously-bullish investors have a...

We develop a model of stock prices in which there are both differences of opinion among investors as well as short-sales constraints. The key insight that emerges is that breadth of ownership is a valuation indicator. When breadth is low i.e., when few investors have long positions in the stock...

This paper is an investigation into the determinants of asymmetries in stock returns. We develop a series of cross-sectional regression specifications which attempt to forecast skewness in the daily returns of individual stocks. Negative skewness is most pronounced in stocks that have...

This paper explores the question of whether hedge funds engage in front-running strategies that exploit the predictable trades of others. One potential opportunity for front-running arises when distressed mutual funds -- those suffering large outflows of assets under management -- are forced to...

Theory suggests that, in the presence of local bias, the price of a stock should be decreasing in the ratio of the aggregate book value of firms in its region to the aggregate risk tolerance of investors in its region. We test this proposition using data on U.S. Census regions and states, and...

We investigate the idea that stock-market participation is influenced by social interaction. We build a simple model in which any given 'social' investor finds it more attractive to invest in the market when the participation rate among his peers is higher. The model predicts higher...

A mutual-fund manager is more likely to hold (or buy, or sell) a particular stock in any quarter if other managers in the same city are holding (or buying, or selling) that same stock. This pattern shows up even when controlling for the distance between the fund manager and the stock in...