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...

The solution to a linear model in which supply and/or demand depends on rational expectations of future prices can involve three parts, which we denote as the fundamental component, the deterministic bubble component, and the stochastic bubble component. This paper explores the properties of...

This paper investigates the nature and the presence of bubbles in financial markets. Are bubbles consistent with rationality? If they are, do they, like Ponzi games, require the presence of new players forever? Do they imply impossible events in finite time, such as negative prices? Do they need...

We analyze how changes in government policy affect stock prices. Our general equilibrium model features uncertainty about government policy and a government that has both economic and non-economic motives. The government tends to change its policy after performance downturns in the private...

Stock-based compensation is the standard solution to agency problems between shareholders and managers. In a dynamic rational expectations equilibrium model with asymmetric information we show that although stock-based compensation causes managers to work harder, it also induces them to hide any...

The mean, co-variability, and predictability of the return of different classes of financial assets challenge the rational economic model for an explanation. The unconditional mean aggregate equity premium is almost seven percent per year and remains high after adjusting downwards the sample...

This paper develops a multi-period rational expectations model of stock trading in which investors have differential information concerning the underlying value of the stock. Investors trade competitively in the stock market based on their private information and the information revealed by the...

This paper presents a simple general equilibrium model of asset pricing in which profitable informed trading can occur without any "noise" added to the model. It shows that models of profitable informed trading must restrict the portfolio choices of uninformed traders: in particular, they cannot...

This paper argues that an important part of movements in asset prices may be caused by neither external news nor irrationality, but the by revelation of information by the trading process itself. Two models are developed that illustrate this general idea. One model is based on investor...

When there is uncertainty about a CEO's quality, news about the firm causes rational investors to update their expectation of the firm's profitability for two reasons: Updates occur because of the direct effect of the news, and also because the news can cause an updated assessment of the CEO's...