In Jouini and Kallal (1995a), the authors characterized the absence of arbitrage opportunities for contingent claims with cash delivery in the presence of bid-ask spreads. Other authors obtained similar results for a more general de nition of the contingent claims but assuming some speci c price...

We define a coherent risk measures as set-valued maps satisfying some axioms. We show that this definition is a convenient extension of the real-valued risk measures introduced by Artzner, Delbaen, Eber and Heath (1998). We then discuss the aggregation issue, i.e. the passage from valued random...

We study the deterministic control problem of maximizing utility from consumption of an agent who seeks to optimally allocate his wealth between consumption and investment in a financial asset subject to taxes on benefits with first-in–first-out priority rule on sales. Short sales are...

When the markets are dynamically complete and without imperfections there are three equivalent approaches in order to price a given asset : the arbitrage approach through the existence of a risk-neutral density, the utility approach through a utility maximization program and the equilibrium...

In this article, we characterize efficient portfolios, i.e. portfolios which are optimal for at least one rational agent, in a very general financial market model with proportional transaction costs. In our setting, transaction costs may be random, time-dependent, have jumps and the preferences...

We provide a discipline for beliefs formation through a model of subjective beliefs, in which agents hold incorrect but strategic beliefs. More precisely, we consider beliefs as a strategic variable that agents can manipulate to maximize their utility from trade. Our framework is therefore an...

We consider a general discrete-time dynamic nancial market with three assets: a riskless bond, a security and a derivative. The market is incomplete (apriori) and at equilibrium. We assume also that the agents of the economy have short-sales constraints on the stock and that the payo at the...

In this paper we analyse the risk attitude of a group of heterogenous agents and we develop a theory of comparative collective risk tolerance. In particular, we characterize how shifts in the distribution of individual levels of risk tolerance affect the representative agent's degree of risk...

The aim of this paper is to establish a compactness result on some function sets. The main idea is very simple : it suffices to change the axis in order to transform a family of nondecreasing functions in Lipschitz ones and then to apply Ascoli's theorem. As we will see, this simple geometrical...

We consider a general equilibrium model in which the production sector may exhibit increasing returns to scale or more general types of nonconvexities. We assume that the firms follow general pricing rules. Under standard assumptions in this model, we establish an index formula, which...