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Journal of Financial and Quantitative Analysis Vol. 45 No. 4 2010

Idiosyncratic Risk, Long-Term Reversal, and Momentum

R. David McLean1,2

1 University of Alberta · 2 Georgetown University

Abstract

This paper tests whether the persistence of the momentum and reversal effects is the result of idiosyncratic risk limiting arbitrage. Idiosyncratic risk deters arbitrage, regardless of the arbitrageur’s diversification. Reversal is prevalent only in high idiosyncratic risk stocks, suggesting that idiosyncratic risk limits arbitrage in reversal mispricing. This finding is robust to controls for transaction costs, informed trading, and systematic relations between idiosyncratic risk and subsequent returns. Momentum is not related to idiosyncratic risk. Momentum generates a smaller aggregate return than reversal, so the findings along with those in related studies suggest that transaction costs are sufficient to prevent arbitrageurs from eliminating momentum mispricing.

DOI
10.1017/s0022109010000311
Volume
45
Issue
4
Pages
883-906
Language
en
Sources
bibtex:phds-export.bib openalex crossref

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