[This article examines the effects of portfolio insurance on market and asset price dynamics in a general equilibrium continuous-time model. Portfolio insurers are modeled as expected utility maximizing agents. Martingale methods are employed in solving the individual agents' dynamic consumption-portfolio problems. Comparisons are made between the optimal consumption processes, optimally invested wealth and portfolio strategies of the portfolio insurers and "normal agents." At a general equilibrium level, comparisons across economies reveal that the market volatility and risk premium are decreased, and the asset and market price levels increased, by the presence of portfolio insurance.]

[We provide fully analytical, optimal dynamic hedges in incomplete markets by employing the traditional minimum-variance criterion. Our hedges are in terms of generalized "Greeks" and naturally extend no-arbitrage-based risk management in complete markets to incomplete markets. Whereas the literature characterizes either minimum-variance static, myopic, or dynamic hedges from which a hedger may deviate unless able to precommit, our hedges are time-consistent. We apply our results to derivatives replication with infrequent trading and determine hedges and replication values, which reduce to generalized Black-Scholes expressions in specific settings. We also investigate dynamic hedging with jumps, stochastic correlation, and portfolio management with benchmarking.]

[We solve the dynamic mean-variance portfolio problem and derive its time-consistent solution using dynamic programming. Previous literature, in contrast, only determines either myopic or precommitment (committing to follow the initially optimal policy) solutions. We provide a fully analytical simple characterization of the dynamically optimal mean-variance portfolios within a general incomplete-market economy. We also identify a probability measure that incorporates intertemporal hedging demands and facilitates tractability. We illustrate this by easily computing portfolios explicitly under various stochastic investment opportunities. A calibration exercise shows that the meanvariance hedging demands are economically significant.]

This article analyzes optimal, dynamic portfolio and wealth/consumption policies of utility maximizing investors who must also manage market-risk exposure using Value-at-Risk (VaR). We find that VaR risk managers often optimally choose a larger exposure to risky assets than non-risk managers and consequently incur larger losses when losses occur. We suggest an alternative risk-management model, based on the expectation of a loss, to remedy the shortcomings of VaR. A general-equilibrium analysis reveals that the presence of VaR risk managers amplifies the stock-market volatility at times of down markets and attenuates the volatility at times of up markets.

This article develops a general equilibrium, continuous time model where portfolio constraints generate mispricing between redundant securities. Constrained consumption-portfolio optimization techniques are adapted to incorporate redundant, possibly mispriced securities. Under logarithmic preferences, we provide explicit conditions for mispricing and closed-form expressions for all economic quantities. Existence of an equilibrium where mispricing occurs with positive probability is verified in a specific case. In a more general setting, we demonstrate the necessity of mispricing for equilibrium when agents are heterogeneous enough. The construction of a representative agent with stochastic weights allows us to characterize prices and allocations, given mispricing occurs.

[This article solves the equilibrium problem in a pure-exchange, continuous-time economy in which some agents face information costs or other types of frictions effectively preventing them from investing in the stock market. Under the assumption that the restricted agents have logarithmic utilities, a complete characterization of equilibrium prices and consumption/investment policies is provided. A simple calibration shows that the model can help resolve some of the empirical asset pricing puzzles.]

This paper develops an intertemporal model of international capital market segmentation. Within the model, under various forms of segmentation/integration, the equilibrium asset prices and allocations, the risk-free interest rate, and the intertemporal consumption behavior and welfares of two countries are derived and compared. It is shown that the equilibrium interest rate is increased on integration, and that integrating markets may be significantly welfare decreasing for one of the countries. Conditions that may lead to a decrease in welfare are investigated. The conclusions as to the effects of segmentation on asset prices in the mean-variance model of the existing finance segmentation literature are also shown to break down in an intertemporal model.

[This article investigates a fund manager's risk-taking incentives induced by an increasing and convex relationship of fund flows to relative performance. In a dynamic portfolio choice framework, we show that the ensuing convexities in the manager's objective give rise to a finite risk-shifting range over which she gambles to finish ahead of her benchmark. Such gambling entails either an increase or a decrease in the volatility of the manager's portfolio, depending on her risk tolerance. In the latter case, the manager reduces her holdings of the risky asset despite its positive risk premium. Our empirical analysis lends support to the novel predictions of the model.]

This article examines the effects of portfolio insurance on market and asset price dynamics in a general equilibrium continuous-time model. Portfolio insurers are modeled as expected utility maximizing agents. Martingale methods are employed in solving the individual agents' dynamic consumption-portfolio problems. Comparisons are made between the optimal consumption processes, optimally invested wealth and portfolio strategies of the portfolio insurers and "normal agents." At a general equilibrium level, comparisons across economies reveal that the market volatility and risk premium are decreased, and the asset and market price levels increased, by the presence of portfolio insurance. Article published by Oxford University Press on behalf of the Society for Financial Studies in its journal, The Review of Financial Studies.

This paper studies the dynamic behavior of security prices in the presence of investors’ heterogeneous beliefs. We provide a tractable continuous-time pure-exchange model and highlight the mechanism through which investors’ differences of opinion enter into security prices. In the determination of equilibrium, we employ a representative investor with stochastic weights and solve for all economic quantities in closed form, including the perceived market prices of risk and interest rate. The basic analysis is generalized to incorporate multiple sources of risk, disagreement about nonfundamentals, and multiple investors. Other applications involving multiple goods and nominal asset pricing within monetary economies are discussed.