A Note on Portfolio Dominance

In the standard portfolio problem, a shift in the distribution of the risky asset is “portfolio-dominated” if it reduces the demand for the risky asset by all risk-averse agents, irrespective of the risk-free rate. We show that the condition obtained by Landsberger and Meilijson (1993), while necessary, is not sufficient for portfolio dominance and we present an exact necessary and sufficient condition.