The Great Diversification and its Undoing

51 Pages Posted: 4 Oct 2010 Last revised: 6 Oct 2010

See all articles by Vasco M. Carvalho

Vasco M. Carvalho

Universitat Pompeu Fabra/CREI; Centre for Economic Policy Research (CEPR); University of Cambridge

Xavier Gabaix

Harvard University - Department of Economics; National Bureau of Economic Research (NBER); Centre for Economic Policy Research (CEPR); European Corporate Governance Institute (ECGI)

Multiple version iconThere are 2 versions of this paper

Date Written: September 2010

Abstract

We investigate the hypothesis that macroeconomic fluctuations are primitively the results of many microeconomic shocks, and show that it has significant explanatory power for the evolution of macroeconomic volatility. We define "fundamental" volatility as the volatility that would arise from an economy made entirely of idiosyncratic microeconomic shocks, occurring primitively at the level of sectors or firms. In its empirical construction, motivated by a simple model, the sales share of different sectors vary over time (in a way we directly measure), while the volatility of those sectors remains constant. We find that fundamental volatility accounts for the swings in macroeconomic volatility in the US and the other major world economies in the past half century. It accounts for the "great moderation" and its undoing. Controlling for our measure of fundamental volatility, there is no break in output volatility. The initial great moderation is due to a decreasing share of manufacturing between 1975 and 1985. The recent rise of macroeconomic volatility is due to the increase of the size of the financial sector. We provide a model to think quantitatively about the large comovement generated by idiosyncratic shocks. As the origin of aggregate shocks can be traced to identifiable microeconomic shocks, we may better understand the origins of aggregate fluctuations.

Suggested Citation

Carvalho, Vasco M. and Gabaix, Xavier, The Great Diversification and its Undoing (September 2010). NBER Working Paper No. w16424. Available at SSRN: https://ssrn.com/abstract=1685729

Vasco M. Carvalho (Contact Author)

Universitat Pompeu Fabra/CREI ( email )

Ramon Trias Fargas, 25-27
Barcelona, 08005
Spain

HOME PAGE: http://www.crei.cat/people/carvalho/welcome.html

Centre for Economic Policy Research (CEPR) ( email )

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United Kingdom

University of Cambridge ( email )

Trinity Ln
Cambridge, CB2 1TN
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Xavier Gabaix

Harvard University - Department of Economics ( email )

Littauer Center
Cambridge, MA 02138
United States

National Bureau of Economic Research (NBER)

1050 Massachusetts Avenue
Cambridge, MA 02138
United States

Centre for Economic Policy Research (CEPR)

London
United Kingdom

European Corporate Governance Institute (ECGI)

c/o ECARES ULB CP 114
B-1050 Brussels
Belgium

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