Global asset allocation provides risk diversification. But international market correlation increases sharply during global crises and diversification benefit disappears when it is most needed. We model these correlation breaks and derive the asset allocation implications. The model can quickly...

In this paper, we introduce a new approach for finding robust portfolios when there is model uncertainty. It differs from the usual worst case approach in that a (dynamic) portfolio is evaluated not only by its performance when there is an adversarial opponent (quot;naturequot;), but also by its...

This paper concerns dynamic pricing of multiple perishable products when there is model uncertainty, which we formulate as a worst-case stochastic intensity control problem where ambiguity is modeled using the notion of relative entropy. One feature of our formulation is that the demand models...

We propose a novel regime-switching model to study correlation asymmetries in international equity markets. We decompose returns into frequent-but-small diffusion and infrequent-but-large jumps, and derive an estimation method for many countries. We find that correlations due to jumps, not...

This paper concerns optimal investment and consumption with CRRA utility when there is event risk. Events are modeled by transitions in a finite state Markov chain, but unlike traditional regime switching models, transitions not only change the instantaneous return statistics but are accompanied...