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28 May 2009Working Paper Summaries

Monopolistic Competition Between Differentiated Products With Demand For More Than One Variety

by Andrei Hagiu
How and when is price competition most significant among firms? This paper develops a theoretical framework for studying price competition between multiple firms. Two examples of markets that fit the description for study are software applications and videogames: There are thousands of software applications as well as games, and different users are interested in different applications and/or games. A given software or game user's tastes may overlap with another's, yet they may have nothing in common with a third's. Thus, although there is a sense in which competition is localized (any given firm competes only with firms whose brands are similar to its own), it is not clear how the fact that consumers are generally interested in purchasing multiple products affects the type of competition waged among firms. Key concepts include:
  • This paper proposes a theoretical framework for studying competition between differentiated products when consumers are interested in purchasing more than one brand.

Author Abstract

We analyze the existence of pure strategy symmetric price equilibria in a generalized version of Salop (1979)'s circular model of competition between differentiated products—namely, we allow consumers to purchase more than one brand. When consumers purchase all varieties from which they derive non-negative net utility, there is no competition, so that each firm behaves like an unconstrained monopolist. When each consumer is interested in purchasing an exogenously given number (n) of varieties, we show that there is no pure strategy symmetric price equilibrium in general (for n > 2 with linear transportation costs). In turn, if the limitation on the number of varieties consumers purchase comes from a budget constraint then we obtain a multiplicity of symmetric price equilibria, which can be indexed by the number of varieties consumers purchase in equilibrium. Keywords: Monopolistic competition, Product Variety. 48 pages.

Paper Information

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