Individual Investors and Volatility

47 Pages Posted: 20 Aug 2008

See all articles by Thierry Foucault

Thierry Foucault

HEC Paris - Finance Department

David Alexandre Sraer

University of California, Berkeley; Princeton University

David Thesmar

Massachusetts Institute of Technology (MIT) - Economics, Finance, Accounting (EFA)

Multiple version iconThere are 2 versions of this paper

Date Written: July 2008

Abstract

We test the hypothesis that individual investors contribute to the idiosyncratic volatility of stock returns because they act as noise traders. To this end, we consider a reform that makes short selling or buying on margin more expensive for retail investors relative to institutions, for a subset of French stocks. If retail investors are noise traders, theory implies that the volatility of stocks affected by the reform should decrease relative to other stocks. This prediction is borne out by the data. Moreover, around the reform, we observe a significant decrease in (i) the magnitude of returns reversals, and (ii) the Amihud ratio for the stocks affected by the reform relative to other stocks. We show that these findings are also consistent with models in which individual investors, acting as noise traders, are a source of volatility.

Keywords: Idiosyncratic volatility, Noise trading, Retail investors

JEL Classification: G11, G12, G14

Suggested Citation

Foucault, Thierry and Sraer, David Alexandre and Thesmar, David, Individual Investors and Volatility (July 2008). CEPR Discussion Paper No. DP6915. Available at SSRN: https://ssrn.com/abstract=1240225

Thierry Foucault (Contact Author)

HEC Paris - Finance Department ( email )

1 rue de la Liberation
Jouy-en-Josas Cedex, 78351
France
(33)139679569 (Phone)
(33)139677085 (Fax)

HOME PAGE: http://thierryfoucault.com/

David Alexandre Sraer

University of California, Berkeley ( email )

310 Barrows Hall
Berkeley, CA 94720
United States

Princeton University ( email )

22 Chambers Street
Princeton, NJ 08544-0708
United States

David Thesmar

Massachusetts Institute of Technology (MIT) - Economics, Finance, Accounting (EFA) ( email )

77 Massachusetts Avenue
Cambridge, MA 02139-4307
United States
16172259767 (Phone)

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