In this paper we consider a model of oligopolistic competition where firms make a two-dimensional product line decision. They choose a location in style space, thus, inducing horizontal differentiation, and produce different qualities (a product line) of a given good (vertical differentiation),...

In this paper, we discuss one of the reasons leading practitionners to the rejection of the Markowitz model and propose a new stastistical method to avoid this problem. To be more precise, we discuss the problem of statistical robustness of the Markowitz optimizer and show that the latter is not...

This paper adapts the methods of Minimax-Hedging developped in Bernis & Giraud [2000] to other models of financial markets, including discontinuous semi-martingale. The measure of the risk is defined as the value of a zero-sum game between the investor and a fictitious player, representing the...