Monopolistic Competition: Beyond the Constant Elasticity of Substitution
We propose a model of monopolistic competition with additive preferences and variable marginal costs. Using the concept of "relative love for variety," we provide a full characterization of the free-entry equilibrium. When the relative love for variety increases with individual consumption, the market generates pro-competitive effects. When it decreases, the market mimics anti-competitive behavior. The constant elasticity of substitution is the only case in which all competitive effects are washed out. We also show that our results hold true when the economy involves several sectors, firms are heterogeneous, and preferences are given by the quadratic utility and the translog.
We propose a general model of monopolistic competition, which encompasses existing models while being flexible enough to take into account new demand and competition features. Even though preferences need not be additive and/or homothetic, the market outcome is still driven by the sole variable elasticity of substitution. We impose elementary conditions on this function to guarantee empirically relevant properties of a free-entry equilibrium. Comparative statics with respect to market size and productivity shocks are characterized through necessary and sufficient conditions. Furthermore, we show that the attention to the CES based on its normative implications was misguided: we propose a new class of preferences, which express consumers' uncertainty about their love for variety, that yield variable markups and may sustain the optimum. Last, we show how our approach can cope with heterogeneous firms once it is recognized that the elasticity of substitution is firm-specific.
In 2000s, Russian large retailers captured a large share of the market and obtained a significant market power. This change in the market organization may enhance or deteriorate social welfare. Public interest in this issue stimulated adoption by the Russian Parliament (State Duma) of the law against the concentration of trade in the hands of a few firms. In this paper we consider the question of efficiency, in terms of social welfare, this kind of state intervention in the relations between retailers and manufacturers.
Many industries are made of a few big firms, which are able to manipulate the market outcome, and of a host of small businesses, each of which has a negligible impact on the market. We provide a general equilibrium framework that encapsulates both market structures. Due to the higher toughness of competition, the entry of big firms leads them to sell more through a market expansion effect generated by the shrinking of the monopolistically competitive fringe. Furthermore, social welfare increases with the number of big firms because the pro-competitive effect associated with entry dominates the resulting decrease in product diversity.