In the standard CAPM with a riskless asset we prove 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.

We demonstrate that in a CAPM economy Walras Law and the Tobin Separation Property characterize market demand in finite sets of prices. Consequently, for any number n there exist CAPM economies which have at least n equilibria and hence have n different beta pricing fomulas. It is shown that the...

Minimum-cost portfolio insurance is an investment strategy that enables an investor to avoid losses while still capturing gains of a payoff of a portfolio at minimum cost. If derivative markets are complete, then holding a put option in conjunction with the reference portfolio provides...

We present a finite system of polynomial inequalities in unobservable endogenous variables and market data that observations on market prices, individual incomes and aggregate endowments must satisfy to be consistent with the equilibrium behavior of some pure exchange economy. We also derive a...

In this Paper we propose a concept of stability for intertemporal equilibria with rational expectations: current period prices move proportionally to current period excess demand while future prices are formed according to the perfect foresight hypothesis. It is shown that this process is...