In this paper, we consider an incumbent firm facing potential entry in a vertical differentiation model a la Mussa and Rosen where consumers differ only by their intensity of preference for quality. We ask whether the incumbent firm has the incentive to adopt a multi-product strategy in order to...

An abundant literature is concerned with the existence of equilibrium in incomplete markets where participation to financial markets is not restricted. To mention a few, Cass (1984), Werner (1985), Geanakoplos and Polemarchakis (1986), Duffie (1987), Duffie and Shafer (1985) and Magill and...