The problem of fair pricing of contingent claims is well understood in the contex of an arbitrage free, complete financial market, with perfect information : the so-called arbitrage approach permits to construct a unique valuation operator compatible with observed price rocesses. In the more...

Standard models for fi…nancial markets are based on the simplifying assumption that trading orders can be given and executed in continuous time with no friction. This assumption is clearly a strong idealization of the reality. In particular, securities should not be described by a single price...

In this paper we derive the implications of the absence of arbitrage in securities markets models where traded securities are subject to short-sales constraints and where the borrowing and lending rates differ. We show that a securities price system is arbitrage free if and only if there exists...

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...

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...

Why do investors keep different opinions even though they learn from their own failures and successes? Why do investors keep different opinions even though they observe each other and learn from their relative failures and successes? We analyze beliefs dynamics when beliefs result from a very...

In this thesis, we propose to test a new behavioral explanation of the equity premium puzzle. This work is based on the heterogeneous beliefs model of Jouini and Napp (2007) according to which, pessimism of investors at the aggregate level leads to very important risk premiums. In this model,...

We derive the implications from the absence of arbitrage in dynamic securities markets with bid-ask spreads. The absence of arbitrage is equivalent to the existence of at least an equivalent probability measure that transforms some process between the bid and the ask price processes of traded...