Motivated by the behavior of asset prices, trading volume and price volatility during historical episodes of asset price bubbles, we present a continuous time equilibrium model where overconfidence generates disagreements among agents regarding asset fundamentals. With short-sale constraints, an asset owner has an option to sell the asset to other overconfident agents when they have more optimistic beliefs. As in Harrison and Kreps (1978), this re-sale option has a recursive structure, that is, a buyer of the asset gets the option to resell it. Agents pay prices that exceed their own valuation of future dividends because they believe that in the future they will find a buyer willing to pay even more. This causes a significant bubble component in asset prices even when small differences of beliefs are sufficient to generate a trade. In equilibrium, large bubbles are accompanied by large trading volume and high price volatility. Our model has an explicit solution, which allows for several comparative statics exercises. Our analysis shows that while Tobin’s tax can substantially reduce speculative trading when transaction costs are small, it has only a limited impact on the size of the bubble or on price volatility. We also give an example where the price of a subsidiary is larger than its parent firm. This paper was previously circulated under the title “Overconfidence, Short-Sale Constraints and Bubbles.”

We examine how investor sentiment affects the cross-section of stock returns. Theory predicts that a broad wave of sentiment will disproportionately affect stocks whose valuations are highly subjective and are difficult to arbitrage. We test this prediction by studying how the cross-section of subsequent stock returns varies with proxies for beginning-of-period investor sentiment. When sentiment is low, subsequent returns are relatively high on smaller stocks, high volatility stocks, unprofitable stocks, non-dividend-paying stocks, extreme-growth stocks, and distressed stocks, consistent with an initial underpricing of these stocks. When sentiment is high, on the other hand, these patterns attenuate or fully reverse. The results are consistent with predictions and appear unlikely to reflect an alternative explanation based on compensation for systematic risk.

We develop a theory in which the decision to pay dividends is driven by investor demand. Managers cater to investors by paying dividends when investors put a stock price premium on payers and not paying when investors prefer nonpayers. To test this prediction, we construct four time series measures of the investor demand for dividend payers. By each measure, nonpayers initiate dividends when demand for payers is high. By some measures, payers omit dividends when demand is low. Further analysis confirms that the results are better explained by the catering theory than other theories of dividends.

This paper documents that hedge funds did not exert a correcting force on stock prices during the technology bubble. Instead, they were heavily invested in technology stocks. This does not seem to be the result of unawareness of the bubble: Hedge funds captured the upturn, but, by reducing their positions in stocks that were about to decline, avoided much of the downturn. Our findings question the efficient markets notion that rational speculators always stabilize prices. They are consistent with models in which rational investors may prefer to ride bubbles because of predictable investor sentiment and limits to arbitrage.

IPO initial returns reached astronomical levels during 1999-2000. We show that the regime shift in initial returns and other elements of pricing behavior can be at least partially accounted for by a variety of marked changes in pre-IPO ownership structure and insider selling behavior over the period, which reduced key decision-makers ’ incentives to control underpricing. After controlling for these changes, the difference in underpricing between 1999-2000 and the preceding three years is much reduced. Our results suggest that it was firm characteristics that were unique during the “dot-com bubble ” and that pricing behavior followed from incentives created by these characteristics.

Building on recent developments in behavioral asset pricing, we develop a model in which an increase in the dispersion of investor beliefs under short-selling constraints predicts a rise in stock price above its fundamental value, or bubble. The model predicts managers respond to bubbles by issuing new equity and increasing capital expenditures. We test these predictions (among others) using the variance of analysts’ earnings forecasts – a proxy for the dispersion of investor beliefs – to identify the “bubble ” component in Tobin’s Q. We document the dynamic response to bubble shocks using a panel data VAR. Using recursive orderings of the VAR for additional identification, we …nd that orthogonalized bubble shocks have positive and statistically significant effects on Tobin’s Q, net equity issuance, and real investment, consistent with the predictions of the model.

Not necessarily. The fundamental value of a firm increases with uncertainty about average future profitability, and this uncertainty was unusually high in the late 1990s. We calibrate a stock valuation model that includes this uncertainty, and compute the level of uncertainty that is needed to match the observed Nasdaq valuations at their peak. This uncertainty seems plausible because it matches not only the high level but also the high volatility of Nasdaq stock prices. We also show that uncertainty about average profitability has the biggest effect on stock prices when the equity premium is low.

Our model of the initial public offering process links the three main empirical IPO ‘anomalies’ – underpricing, hot issue markets, and long-run underperformance – and traces them to a common source of inefficiency. We relate hot IPO markets (such as the 1999/2000 market for Internet IPOs) to the presence of a class of investors who are ‘irrational’ in the sense of having exuberant expectations regarding future performance. Underpricing and long-run underperformance emerge as underwriters attempt to maximize profits from the sale of equity, at the expense of these exuberant investors. Underpricing serves to compensate regular IPO investors for their role in restricting the supply of available shares and maintaining prices. The model is shown to be consistent with many aspects of the IPO process. It also generates a number of new empirical predictions.

This paper reviews and extends the mathematical finance literature on bubbles in complete markets. We provide a new characterization theorem for bubbles under the standard no arbitrage (NFLVR) framework, showing that bubbles can be of three types. Type 1 bubbles are uniformly integrable martingales, and these can exist with an infinite lifetime. Type 2 bubbles are non-uniformly integrable martingales, and these can exist for a finite, but unbounded, lifetime. Last, type 3 bubbles are strict local martingales, and these can exist for a finite lifetime only. When one adds a no dominance assumption (from Merton [24]), only type 1 bubbles remain. In addition, under Merton’s no dominance hypothesis, put-call parity holds and there are no bubbles in standard call and put options. Our analysis implies that if one believes asset price bubbles exist and are an important economic phenomena, then asset markets must be incomplete.

Research in behavioral corporate finance takes two distinct approaches. The first emphasizes that investors are less than fully rational. It views managerial financing and investment decisions as rational responses to securities market mispricing. The second approach emphasizes that managers are less than fully rational. It studies the effect of nonstandard preferences and judgmental biases on managerial decisions. This survey reviews the theory, empirical challenges, and current evidence pertaining to each approach. Overall, the behavioral approaches help to explain a number of important financing and investment patterns. The survey closes with a list of open questions.