Competition Among the Big and the Small

37 Pages Posted: 8 Sep 2009

See all articles by Ken-Ichi Shimomura

Ken-Ichi Shimomura

Kobe University

Jacques-François Thisse

Catholic University of Louvain (UCL); Centre for Economic Policy Research (CEPR)

Date Written: August 2009


Armchair evidence shows that many industries are made of a few big commercial or manufacturing firms, which are able to affect the market outcome, and of a myriad of small family-run businesses with very few employees, each of which has a negligible impact on the market. Examples can be found in apparel, catering, publishers and bookstores, retailing, finance and insurances, and IT industries. We provide a new general equilibrium framework that encapsulates both market structures. Due to the higher toughness of the market, the entry of big firms leads them to sell more through a market expansion effect, which is generated by the exit of small firms. Furthermore, the level of social welfare increases with the number of oligopolistic firms because the procompetitive effect associated with the entry of a big firm dominates the resulting decrease in product variety.

Keywords: monopolistic competition, oligopoly, product differentiation, welfare

JEL Classification: L13, L40

Suggested Citation

Shimomura, Ken-Ichi and Thisse, Jacques-François, Competition Among the Big and the Small (August 2009). CEPR Discussion Paper No. DP7404. Available at SSRN:

Ken-Ichi Shimomura

Kobe University ( email )

2-1, Rokkodai-cho, Nada-ku
Kobe, 657-8501, 657-8501

Jacques-François Thisse (Contact Author)

Catholic University of Louvain (UCL) ( email )

Place des Doyens 1
Louvain-la-Neuve, 1348

Centre for Economic Policy Research (CEPR)

United Kingdom

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