In the standard CAPM with a riskless asset we give a simple proof of existence of equilibria without assuming concavity of the investor's utility functions. Moreover, we give a uniqueness result using assumptions on the risk aversion of investors.

In the standard CAPM with a riskless asset we give a sufficient condition for uniqueness. This condition is a joint restriction on the agents´ endowments and their preferences which is compatible with non-increasing absolute risk aversion and which is inparticular satisfied with constant...