期刊名称：CORE Discussion Papers / Center for Operations Research and Econometrics (UCL), Louvain
出版年度：2009
卷号：1
出版社：Center for Operations Research and Econometrics (UCL), Louvain
摘要：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.
