The paper studies the two period incomplete markets model where assets are claims on state contingent commodity bundles and there are no bounds on portfolio trading. The important results on the existence of equilibrium in this model assume that there is a infnite number of commodities traded in...

This paper shows that, indeed , Aumann's classical existence and equivalence theorems depend on there being many more agents than commodities. We show that for an arbitrary atomless measure space of agents three is a fixed non-separable infinite dimensional commodity space in which one can...

Investors often wish to insure themselves against the payoff of their portfolios falling below a certain value. One way of doing this is by purchasing an appropriate collection of traded securities. However, when the derivatives market is not complete, an investor who seeks portfolio insurance...

This paper presents a surprising example. It shows that lattice theoretic properties in Mas-Colell's (1986) seminal work are relevant to the existence of equilibrium problem even when commodity space is finite dimensional. The paper provides an example of an economy with three commodities and...

The second welfare theorem and the core-equivalence theorem have been proved to be fundamental tools for obtaining equilibrium existence theorems, especially in an infinite dimensional setting. For well-behaved exchange economies that we call proper economies, this paper gives (minimal)...