Monetary and Economic Studies Vol.20, No.3 / October 2002

Comparative Analyses of Expected Shortfall and Value-at-Risk (3): Their Validity under Market Stress

Yasuhiro Yamai, Toshinao Yoshiba

In this paper, we compare value-at-risk (VaR) and expected shortfall under market stress. Assuming that the multivariate extreme value distribution represents asset returns under market stress, we simulate asset returns with this distribution. With these simulated asset returns, we examine whether market stress affects the properties of VaR and expected shortfall.Our findings are as follows. First, VaR and expected shortfall may underestimate the risk of securities with fat-tailed properties and a high potential for large losses. Second, VaR and expected shortfall may both disregard the tail dependence of asset returns. Third, expected shortfall has less of a problem in disregarding the fat tails and the tail dependence than VaR does.

Keywords: Value-at-risk; Expected shortfall; Market stress; Tail risk; Multivariate extreme value theory; Tail dependence

Views expressed in the paper are those of the authors and do not necessarily reflect those of the Bank of Japan or Institute for Monetary and Economic Studies.

Copyright © 2002 Bank of Japan All Rights Reserved.

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