Portfolio Allocation Problems between Risky and Ambiguous Assets

Abstract

This paper considers a portfolio allocation problem between a risky asset and an ambiguous asset, and investigates how the existence of ambiguity influences the optimal proportion invested in the two assets. By introducing the notion of ambiguity, we derive several sufficient conditions under which an investor decreases the optimal proportion invested in the ambiguous asset. Furthermore, as an application, we consider an international diversification problem, and show that the home bias puzzle is partially resolved.