Arbitrage and equilibrium in economies with short-selling and ambiguity

Thai Ha-Huy (University of Evry Paris-Saclay) & Cuong Le Van & Cuong Tran Viet (University Paris 1)

 

We consider a model with a finite number of states of nature where short sells are allowed. We present a notion of no-arbitrage price weaker than the one of Werner (1987) that we call weak no-arbitrage price. We prove that in the case of maximin expected utility functions, the existence of one common weak no-arbitrage price is equivalent to the existence of an equilibrium.