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...

Among U.S. public firms, technological innovation is concentrated in a small set of large players, with innovation “leaders” having considerably lower systematic risk than “laggards.” To understand this fact, we build a winner-takes-all patent-race model and show that a firm's expected...