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Quantifying the gap between equilibrium and optimum under monopolistic competition

Kristian Behrens, Giordano Mion, Yasusada Murata and Jens Sudekum


Equilibria and optima generally differ in imperfectly competitive markets. Although this is well understood theoretically, it is unclear how large the welfare distortions are in the aggregate economy. Do they matter quantitatively? To answer this question, we develop a multisector monopolistic competition model with endogenous firm entry and selection, productivity, and markups. Using French and UK data, we quantify the gap between the equilibrium and optimal allocations. We find that inefficiencies in the labor allocation and entry between sectors, as well as inefficient selection and output per firm within sectors, generate welfare losses of about 6%?10% of GDP. ? The Author(s) 2020.


1 November 2020


Quarterly Journal of Economics 135(4) , pp.2299-2360, 2020


DOI: 10.1093/qje/qjaa017

https://academic.oup.com/qje/article-abstract/135/4/2299/5837098?redirectedFrom=fulltext

This Journal article is published under the centre's Trade programme.