We study a simple bilateral oligopoly model in which individual agents, who are initially endowed with capital, decide sequentially (1) whether they want to act as producers (entrepreneurs) or as capital lenders (rentiers) and, then (2) which quantity of capital they would like to borrow or lend, though exchange of capital units against units of the produced good. Production takes place under increasing returns to scale. We show the existence of “natural equilibria”, at which wealthier capital owners become entrepreneurs while the remaining ones decide to be rentiers. We also study the efficiency of equilibria which is shown to increase by replication of the economy, but sometimes to decrease as a consequence of wealth redistribution.

We study a model with product differentiation by manufacturers and spatial differentiation by supermarkets where the customers visit only one shop and the supermarkets carry both goods. Under fixed fee pricing by the manufacturers the intensity of interbrand competition increases with the degree of differentiation between the supermarkets. When the supermarkets are more and more spatially differentiated the struggle between manufacturers and supermarkets dominates the competition between the manufacturers and results in lower wholesale prices and manufacturers profits.

We examine how media competition is affected when making endogenous advertising rates. To this end, we revisit some well-known contributions in which advertising rates and volumes are viewed as exogenous, so that the effects of advertising on diversity and industry concentration only depend on the size of the audience, without taking into account how the media audience depends itself on advertising rates. We rely on the two-sided market structure which characterizes the media and advertising industry and allows advertising rates and audience size to be jointly determined at equilibrium. Finally, we study how making the advertising rate dependent on the audience size may influence the content and diversity of the media industry. Copyright Blackwell Publishing Ltd and The University of Manchester, 2006.

The objective of this article is to bring a new light to the literature on the ?home market effect? based on the pioneering article by Helpman and Krugman (1985). We present some works which show that the existence of net trade between two countries of different sizes, the trade structure and the pattern of specialization can highly depend on the relative size of the large country.