A risk-factor model foundation for ratings-based bank capital rules
AbstractWhen economic capital is calculated using a portfolio model of credit value-at-risk, the marginal capital requirement for an instrument depends, in general, on the properties of the portfolio in which it is held. By contrast, ratings-based capital rules, including both the current Basel Accord and its proposed revision, assign a capital charge to an instrument based only on its own characteristics. I demonstrate that ratings-based capital rules can be reconciled with the general class of credit VaR models. Contributions to VaR are portfolio-invariant only if (a) there is only a single systematic risk factor driving correlations across obligors, and (b) no exposure in a portfolio accounts for more than an arbitrarily small share of total exposure. Analysis of rates of convergence to asymptotic VaR leads to a simple and accurate portfolio-level add-on charge for undiversified idiosyncratic risk. There is no similarly simple way to address violation of the single factor assumption.
Download InfoIf you experience problems downloading a file, check if you have the proper application to view it first. In case of further problems read the IDEAS help page. Note that these files are not on the IDEAS site. Please be patient as the files may be large.
Bibliographic InfoPaper provided by Board of Governors of the Federal Reserve System (U.S.) in its series Finance and Economics Discussion Series with number 2002-55.
Date of creation: 2002
Date of revision:
Other versions of this item:
- Gordy, Michael B., 2003. "A risk-factor model foundation for ratings-based bank capital rules," Journal of Financial Intermediation, Elsevier, vol. 12(3), pages 199-232, July.
- NEP-ALL-2003-01-27 (All new papers)
- NEP-FIN-2003-01-27 (Finance)
- NEP-RMG-2003-01-27 (Risk Management)
Please report citation or reference errors to , or , if you are the registered author of the cited work, log in to your RePEc Author Service profile, click on "citations" and make appropriate adjustments.:
- Gordy, Michael B., 2000.
"A comparative anatomy of credit risk models,"
Journal of Banking & Finance,
Elsevier, vol. 24(1-2), pages 119-149, January.
- Carlo Acerbi & Dirk Tasche, 2001.
"On the coherence of Expected Shortfall,"
cond-mat/0104295, arXiv.org, revised May 2002.
- Gouriéroux, Christian & Laurent, J.P. & Scaillet, Olivier, 1999.
"Sensitivity Analysis of Values at Risk,"
Discussion Papers (IRES - Institut de Recherches Economiques et Sociales)
2000002, Université catholique de Louvain, Institut de Recherches Economiques et Sociales (IRES), revised 00 Jan 2000.
- Christian Gourieroux & Jean-Paul Laurent & Olivier Scaillet, 2000. "Sensitivity Analysis of Values at Risk," Working Papers 2000-05, Centre de Recherche en Economie et Statistique.
- C. Gourieroux & J.P. Laurent & O. Scaillet, 2000. "Sensitivity analysis of values at risk," THEMA Working Papers 2000-04, THEMA (THéorie Economique, Modélisation et Applications), Université de Cergy-Pontoise.
- Christian Gourieroux & J. P. Laurent & Olivier Scaillet, 2000. "Sensitivity Analysis of Values at Risk," Econometric Society World Congress 2000 Contributed Papers 0162, Econometric Society.
- Dirk Tasche, 2001. "Conditional Expectation as Quantile Derivative," Papers math/0104190, arXiv.org.
- Jones, David, 2000. "Emerging problems with the Basel Capital Accord: Regulatory capital arbitrage and related issues," Journal of Banking & Finance, Elsevier, vol. 24(1-2), pages 35-58, January.
- Frey, Rudiger & McNeil, Alexander J., 2002. "VaR and expected shortfall in portfolios of dependent credit risks: Conceptual and practical insights," Journal of Banking & Finance, Elsevier, vol. 26(7), pages 1317-1334, July.
- Dirk Tasche, 2002.
"Expected Shortfall and Beyond,"
cond-mat/0203558, arXiv.org, revised Oct 2002.
- Mark Carey, 2001. "Dimensions of Credit Risk and Their Relationship to Economic Capital Requirements," NBER Chapters, in: Prudential Supervision: What Works and What Doesn't, pages 197-232 National Bureau of Economic Research, Inc.
- Szego, Giorgio, 2002. "Measures of risk," Journal of Banking & Finance, Elsevier, vol. 26(7), pages 1253-1272, July.
- repec:fth:inseep:2000-05 is not listed on IDEAS
- William F. Treacy & Mark S. Carey, 1998. "Credit risk rating at large U.S. banks," Federal Reserve Bulletin, Board of Governors of the Federal Reserve System (U.S.), issue Nov, pages 897-921.
- Rockafellar, R. Tyrrell & Uryasev, Stanislav, 2002. "Conditional value-at-risk for general loss distributions," Journal of Banking & Finance, Elsevier, vol. 26(7), pages 1443-1471, July.
- Philippe Artzner & Freddy Delbaen & Jean-Marc Eber & David Heath, 1999. "Coherent Measures of Risk," Mathematical Finance, Wiley Blackwell, vol. 9(3), pages 203-228.
This item has more than 25 citations. To prevent cluttering this page, these citations are listed on a separate page. reading list or among the top items on IDEAS.Access and download statisticsgeneral information about how to correct material in RePEc.
For technical questions regarding this item, or to correct its authors, title, abstract, bibliographic or download information, contact: (Kris Vajs).
If references are entirely missing, you can add them using this form.