We study the effects of correlation ambiguity on portfolio choice in a market with multiple risky assets. We find that the optimal portfolio contains only a fraction of risky assets under correlation ambiguity, and in particular, just one risky asset enters the optimal portfolio if the level of...

This paper establishes general conditions for the validity of mutual fund separation and the equilibrium CAPM. We use partial preference orders that display weak form mean preserving spread (w-MPS) risk aversion in the sense of Ma (2011). We derive this result without imposing any distributional...