I study convergence traders with logarithmic utility in a continuous-time equilibrium model. In general, convergence traders reduce asset price volatility and provide liquidity by taking risky positions against noise trading. However, when an unfavorable shock causes them to suffer capital losses, thus eroding their risk-bearing capacity, they liquidate their positions, thereby amplifying the original shock. In extreme circumstances, this wealth effect causes convergence traders to be destabilizing in that they trade in exactly the same direction as noise traders. This situation is consistent with the near-collapse of Long-Term Capital Management in 1998.

A number of authors have suggested that investors derive utility from realizing gains and losses on assets that they own. We present a model of this “realization utility,” analyze its predictions, and show that it can shed light on a number of puzzling facts. These include the disposition effect, the poor trading performance of individual investors, the higher volume of trade in rising markets, the effect of historical highs on the propensity to sell, the individual investor preference for volatile stocks, the low average return of volatile stocks, and the heavy trading associated with highly valued assets.

We investigate whether prospect theory preferences can predict a disposition effect. We consider two implementations of prospect theory: in one case, preferences are defined over annual gains and losses; in the other, they are defined over realized gains and losses. Surprisingly, the annual gain/loss model often fails to predict a disposition effect. The realized gain/loss model, however, predicts a disposition effect more reliably. Utility from realized gains and losses may therefore be a useful way of thinking about certain aspects of individual investor trading.

Financial contagion is described as a wealth effect in a continuous‐time model with two risky assets and three types of traders. Noise traders trade randomly in one market. Long‐term investors provide liquidity using a linear rule based on fundamentals. Convergence traders with logarithmic utility trade optimally in both markets. Asset price dynamics are endogenously determined (numerically) as functions of endogenous wealth and exogenous noise. When convergence traders lose money, they liquidate positions in both markets. This creates contagion, in that returns become more volatile and more correlated. Contagion reduces benefits from portfolio diversification and raises issues for risk management.

Motivated by the behavior of asset prices, trading volume, and price volatility during episodes of asset price bubbles, we present a continuous-time equilibrium model in which overconfidence generates disagreements among agents regarding asset fundamentals. With short-sale constraints, an asset buyer acquires an option to sell the asset to other agents when those agents have more optimistic beliefs. As in a paper by Harrison and Kreps, 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, bubbles are accompanied by large trading volume and high price volatility. 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 study the joint responses of commodity future prices and positions of various trader groups to changes of the CBOE Volatility Index (VIX) before and after the recent financial crisis. Financial traders reduced their net long positions during the crisis in response to market distress, whereas hedgers facilitated this by reducing their net short positions as prices fell. This “convective risk flow” induced by the greater distress of financial institutions led to a change in the allocation of risk with hedgers holding more risk than they did previously. The presence of such a risk flow confirms the market impact of financial traders conditional on trades they initiate.

This paper develops a model to explain the widely used investment mandates in the institutional asset management industry based on two insights: first, giving a manager more investment flexibility weakens the link between fund performance and his effort in the designated market, and thus increases agency cost. Second, the presence of outside assets with negatively skewed returns can further increase the agency cost if the manager is incentivized to pursue outside opportunities. These effects motivate narrow mandates and tight tracking error constraints to most fund managers except those with exceptional talents. Our model sheds light on capital immobility and market segmentation that are widely observed in financial markets, and highlights important effects of negatively skewed risk on institutional incentive structures.

Motivated by psychological evidence that attention is a scarce cognitive resource, we model investors’ attention allocation in learning and study the effects of this on asset-price dynamics. We show that limited investor attention leads to category-learning behavior, i.e., investors tend to process more market and sector-wide information than firm-specific information. This endogenous structure of information, when combined with investor overconfidence, generates important features observed in return comovement that are otherwise difficult to explain with standard rational expectations models. Our model also demonstrates new cross-sectional implications for return predictability.

This article analyzes the dynamic coordination problem among creditors of a firm with a time-varying fundamental and a staggered debt structure. In deciding whether to roll over his debt, each maturing creditor is concerned about the rollover decisions of other creditors whose debt matures during his next contract period. We derive a unique threshold equilibrium and characterize the roles of fundamental volatility, credit lines, and debt maturity in driving runs. In particular, we show that when fundamental volatility is sufficiently high, commonly used measures such as temporarily keeping the firm alive under runs and increasing debt maturity can exacerbate rather than mitigate runs.

We present a multiperiod agency model of stock-based executive compensation in a speculative stock market, where investors have heterogeneous beliefs and stock prices may deviate from underlying fundamentals and include a speculative option component. This component arises from the option to sell the stock in the future to potentially overoptimistic investors. We show that optimal compensation contracts may emphasize short-term stock performance, at the expense of long-run fundamental value, as an incentive to induce managers to pursue actions which increase the speculative component in the stock price. Our model provides a different perspective on the recent corporate crisis than the “rent extraction view” of executive compensation.