The choice of an agent between risky and riskless assets is complicated by the existence of idiosyncratic risk. In this paper the agent chooses state-dependent shares of aggregate marketable income (a sharing rule) to provide a partial hedge against the idiosyncratic risk. The agent's Utility...

We present a necessary and sufficient condition on an agent's utility function for a simple mean preserving spread in an independent background risk to increase the agent's risk aversion (incremental risk vulnerability). Gollier and Pratt (1996) have shown that declining and convex risk aversion...