A General Approach to Integrated Risk Management with Skewed, Fat-Tailed Risk

70 Pages Posted: 10 Feb 2006

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Abstract

The goal of integrated risk management in a financial institution is to measure and manage risk and capital across a range of diverse business activities. This requires an approach for aggregating risk types (market, credit, and operational) whose distributional shapes vary considerably. In this paper, we construct the joint risk distribution for a typical large, internationally active bank using the method of copulas. This technique allows us to incorporate realistic marginal distributions that capture some of the essential empirical features of these risks like skewness and fat-tails while allowing for a rich dependence structure. We explore the impact of business mix and inter-risk correlations on total risk, whether measured by value-at-risk or expected shortfall. We find that given a risk type, total risk is more sensitive to differences in business mix or risk weights than to differences in inter-risk correlations. There is a complex relationship between volatility and fat-tails in determining the total risk: depending on the setting, they either offset or reinforce each other. The choice of copula (normal versus Student-t), which determines the level of tail dependence, has a more modest effect on risk. We then compare the copula-based method with several conventional approaches to computing risk, each of which may be thought of as an approximation. One easily implemented approximation, which uses empirical correlations and quantile estimates, tracks the copula approach surprisingly well. In contrast, the additive approximation, which assumes no diversification benefit, typically overestimates risk by about 30-40%.

Keywords: Market risk, credit risk, operational risk, risk diversification, copula

JEL Classification: G10, G20, G28, C16

Suggested Citation

Rosenberg, Joshua V. and Schuermann, Til, A General Approach to Integrated Risk Management with Skewed, Fat-Tailed Risk. Journal of Financial Economics, Forthcoming; FRB of New York Staff Report No. 185. Available at SSRN: https://ssrn.com/abstract=880422

Joshua V. Rosenberg

Federal Reserve Bank of New York ( email )

33 Liberty Street
New York, NY 10045
United States
212-720-6317 (Phone)
212-720-1582 (Fax)

HOME PAGE: http://www.ny.frb.org/research/economists/rosenberg/index.html

Til Schuermann (Contact Author)

Oliver Wyman ( email )

1166 6th Avenue
New York City, NY
United States

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