Critical Finance Review > Vol 12 > Issue 1-4

Idiosyncratic Equity Risk Two Decades Later

John Y. Campbell, Harvard University, and NBER, USA, , Martin Lettau, University of California at Berkeley, NBER, and CEPR, USA, , Burton Malkiel, Princeton University, USA, , Yexiao Xu, University of Texas at Dallas, USA,
Suggested Citation
John Y. Campbell, Martin Lettau, Burton Malkiel and Yexiao Xu (2023), "Idiosyncratic Equity Risk Two Decades Later", Critical Finance Review: Vol. 12: No. 1-4, pp 203-223.

Publication Date: 08 Aug 2023
© 2023 John Y. Campbell, Martin Lettau, Burton Malkiel and Yexiao Xu
Idiosyncratic volatilityIndustry volatilityMarket volatilityMarket microstructure


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In this article:
1. Introduction 
2. Idiosyncratic Volatility in Recent Data 
3. Market Microstructure and Volatility Measurement 
4. The Economic Interpretation of Idiosyncratic Volatility 
5. Conclusion 


This paper reviews the literature on idiosyncratic equity volatility since the publication of “Have Individual Stocks Become More Volatile? An Empirical Exploration of Idiosyncratic Risk” in 2001. We respond to replication studies by Chiah, Gharghori, and Zhong and by Leippold and Svaton, and we present volatility estimates through the end of 2021, significantly extending the period covered in our original paper as well as the two replication studies. After spiking in the 1999 to 2000 period, idiosyncratic volatility declined thereafter; but sharp increases in market, industry, and idiosyncratic volatility occurred during the global financial crisis of 2008 to 2009 and the COVID-19 pandemic of 2020 to 2021. We argue that market microstructure effects are not of first-order importance for volatility measurement, and we discuss the roles of fundamental factors and investor sentiment in driving the observed fluctuations in volatility.



Critical Finance Review, Volume 12, Issue 1-4 Special Issue: Volatility and Higher Moments: Articles Overview
See the other articles that are part of this special issue.