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Diversification and Value-at-Risk

delete2010-01-01
delete51
PRE
AI
C
Christophe Pérignon
D
Daniel R. Smith *
DOI:10.1016/j.jbankfin.2009.07.003delete
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摘要

摘要

En 中文
A pervasive and puzzling feature of banks' Value-at-Risk (VaR) is its abnormally high level, which leads to excessive regulatory capital. A possible explanation for the tendency of commercial banks to overstate their VaR is that they incompletely account for the diversification effect among broad risk categories (e.g., equity, interest rate, commodity, credit spread, and foreign exchange). By underestimating the diversification effect, bank's proprietary VaR models produce overly prudent market risk assessments. In this paper, we examine empirically the validity of this hypothesis using actual VaR data from major US commercial banks. In contrast to the VaR diversification hypothesis, we find that US banks show no sign of systematic underestimation of the diversification effect. In particular, diversification effects used by banks is very close to (and quite often larger than) our empirical diversification estimates. A direct implication of this finding is that individual VaRs for each broad risk category, just like aggregate VaRs, are biased risk assessments. (C) 2009 Elsevier B.V. All rights reserved.
Keyword:
Value-at-Risk
Diversification
Dynamic conditional correlation
Copulas

期刊

J
Journal of Banking and Finance
IF:
3.8
论文数:
6.4K
被引数:
2.4W

机构

S
Simon Fraser University
学者数:
1.0W
论文数: 1.0W
被引数: 1.4W
H
hautes etudes commerciales (hec) paris
学者数:
392
论文数: 584
被引数: 2
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