Multi-period Markowitz's mean–variance portfolio selection with state-dependent exit probability

This paper considers a multi-period mean–variance portfolio selection problem with uncertain time-horizon in a regime-switching market, where the conditional distribution of the time-horizon is assumed to be stochastic and depends on the market states as the returns of risky assets do. Existence of the optimal investment strategy is analyzed, and the closed-form expressions for the optimal investment strategy and the efficient frontier are derived. In addition, some interesting properties of the efficient frontier are illustrated by numerical analysis and by comparing with the efficient frontier of the case where the distribution of the uncertain time-horizon does not depend on market states.     

The portfolio strategy and hedging: A spectrum perspective on mean–variance theory

This paper aims to establish a portfolio strategy using information of lead–lag relationship. The efficient frontier in mean–variance theory has confirmed that the spectrum strategy established by the lead–lag relationship yields superior performance assuming the same volatility. And then we construct the spectrum portfolios based on two approaches: a recursive approach, which uses a recursive method in the lead–lag relationship, and a joint approach, which combines two lead–lag relationships. The effect of the spectrum strategy using mutual fund data from 1999 through 2009 is examined. The results indicate that the spectrum portfolio has a superior performance as compared to the benchmark with both approaches. Furthermore, the spectrum portfolio by recursive approach maintains superior performance in hedging.     

Multi-period mean–variance asset–liability management with uncontrolled cash flow and uncertain time-horizon

This paper considers an asset–liability management problem under a multi-period mean–variance model with uncontrolled cash flow and uncertain time-horizon. The difference from the existing literature is that the liability is assumed to be influenced not only by the stochastic return of the liability but also by some uncontrolled cash flows, which can be explained as, for example, stochastic expenditure of individual investors, or claim processes of insurers. Firstly, the original problem is translated into a standard multi-period stochastic optimal control problem by introducing a Lagrange multiplier, and the corresponding analytical solution is derived by adopting the dynamic programming approach. Secondly, according to Lagrange duality theorem, closed-form expressions for the efficient investment strategy and the mean–variance efficient frontier are obtained. Moreover, a multi-period version of two-fund separation theorem is proved, and some special cases are discussed. Finally, some numerical examples are presented to illustrate our results.     

Observational equivalence and nonequivalence of subjective and robust mean–variance preferences

We identify the conditions where robust mean–variance preferences, which capture ambiguity aversion, are observationally nonequivalent to subjective mean–variance preferences. Conversely, we also provide an example showing that observational equivalence holds regardless of the degree of ambiguity aversion.     

A copula–GARCH model for macro asset allocation of a portfolio with commodities

Many authors have suggested that the mean-variance criterion, conceived by Markowitz (The Journal of Finance 7(1):77–91, 1952), is not optimal for asset allocation, because the investor expected utility function is better proxied by a function that uses higher moments and because returns are distributed in a non-Normal way, being asymmetric and/or leptokurtic, so the mean-variance criterion cannot correctly proxy the expected utility with non-Normal returns. In Riccetti (The use of copulas in asset allocation: when and how a copula model can be useful? LAP Lambert, Saarbrücken 2010), a copula–GARCH model is applied and it is found that copulas are not useful for choosing among stock indices, but can be useful in a macro asset allocation model, that is, for choosing stock and bond composition of portfolios. In this paper I apply that copula–GARCH model for the macro asset allocation of portfolios containing a commodity component. I find that the copula model appears to be useful and better than the mean-variance one for the macro asset allocation also in presence of a commodity index, even if it is not better than GARCH models on independent univariate series, probably because of the low correlation of the commodity index returns to the stock, the bond and the exchange rate returns.     

Ex post participation constraint in a principal–agent model with adverse selection and moral hazard

This paper analyzes optimal contracting when an agent has private information before contracting and exerts hidden effort that stochastically affects the output. Additionally, the contract is constrained to satisfy the agentʼs ex post participation. We highlight three features of this model. First, the agent faces countervailing incentives. Second, the separation of types is never optimal. Third, the optimal constant bonus rewarding success is distorted downward below its efficient level.