Fusion et groupage en differenciation verticale

This thesis is a collection of three essays on mergers and bundling in vertically differentiated markets.; The first essay studies horizontal mergers of firms producing vertically differentiated goods when the average costs of quality are convex and either fixed or variable in production. We show that in a duopoly: (i) the merged firm produces only one quality if production costs are fixed; and (ii) the merged firm produces the two qualities if production costs are variable. We demonstrate that the social planner chooses the same variety of qualities as the merged firm. In the case of variable production costs, both the social planner and the merged firm choose the same qualities. We find that social welfare is reduced in both cases. We show that this welfare reduction is higher when the production costs are fixed and lower when these costs are variables when compared to horizontal mergers where only prices adjustments are considered and not qualities'. We give implications for efficiencies defence.; The second essay analyzes bundling incentives in markets where products are composed of two complementary components. One of the components is monopolized and the other is sold by a duopoly. We assume quality differentiation between the components. We develop a model of quality competition a la Mussa and Rosen (1978). We demonstrate that the decision of the monopolist to bundle depends on the quality of the component where he faces a rival. We show that: (i) if the monopolist's component has a higher quality than the competitor's, then the monopolist prefers not to bundle (component selling); and (ii) if the quality of monopolist's component is lower than the competitor's, then the monopolist prefers bundling. Thus, the monopolist's incentive not to bundle is related to narrowing of market for its monopolized component. We also consider a dynamic game where firms compete in two-stages (quality and price) and determine the subgame perfect Nash equilibrium. Finally, we discuss antitrust implications of these results.; The third essay looks at the competition and the welfare effects of bundling in the context of vertically differentiated products. We consider a two-stage game with two asymmetric firms. In the first stage firms simultaneously commit to adopt bundling or component pricing. These decisions give four possible configurations: (i) a configuration where both firms use component pricing; (ii) a configuration where both firms use bundling; and finally (iii) the two configurations where one firm use bundling and the other firm does not. In the second stage firms set simultaneously prices. We show that bundling is a dominant strategy equilibrium for both firms. The reason is that bundling increases the differentiation of services and reduces the intensity of price competition. We also find that although the bundling-bundling equilibrium reduces consumers' surplus, total economic welfare is higher than when both firms use component pricing.; Keywords: antitrust, bundling, complementarity, Internet, mergers, monopolization, quality, social welfare, telephone, television.; JEL Classification: L14, L15, L40, L41, L42...