In this article, I discuss the role a progressive income tax system and a redistributive pay as you go (PAYGO) social security system can play in insuring and reallocating idiosyncratic as well as aggregate risk. I also argue that the underlying source of market failures generating such a role...

This paper analyzes dynamic equilibrium risk sharing contracts between profit-maximizing intermediaries and a large pool of ex-ante identical agents that face idiosyncratic income uncertainty that makes them heterogeneous ex-post. In any given period, after having observed her income, the agent...