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The Manipulation of Basel Risk-Weights


  • Mariathasan, Mike
  • Merrouche, Ouarda


In this paper, we examine the relationship between banks’ approval for the internal ratings-based (IRB) approaches of Basel II and the ratio of risk-weighted over total assets. Analysing a panel of 115 banks from 21 OECD countries that were eventually approved for applying the IRB to their credit portfolio, we find that risk-weight density is lower once regulatory approval is granted. The effect persists when we control for different loan categories, and we provide evidence showing that it cannot be explained by flawed modelling, or improved risk-measurement alone. Consistent with theories of risk-weight manipulation, we find the decline in risk-weights to be particularly prevalent among weakly capitalised banks, when the legal framework for supervision is weak, and in countries where supervisors are overseeing many IRB banks. We conclude that part of the decline in reported riskiness under the IRB results from banks’ strategic risk-modelling.

Suggested Citation

  • Mariathasan, Mike & Merrouche, Ouarda, 2013. "The Manipulation of Basel Risk-Weights," CEPR Discussion Papers 9494, C.E.P.R. Discussion Papers.
  • Handle: RePEc:cpr:ceprdp:9494

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    References listed on IDEAS

    1. Blum, Jürg M., 2008. "Why 'Basel II' may need a leverage ratio restriction," Journal of Banking & Finance, Elsevier, vol. 32(8), pages 1699-1707, August.
    2. Huizinga, Harry & Laeven, Luc, 2012. "Bank valuation and accounting discretion during a financial crisis," Journal of Financial Economics, Elsevier, vol. 106(3), pages 614-634.
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    4. James J. Heckman, 1976. "The Common Structure of Statistical Models of Truncation, Sample Selection and Limited Dependent Variables and a Simple Estimator for Such Models," NBER Chapters,in: Annals of Economic and Social Measurement, Volume 5, number 4, pages 475-492 National Bureau of Economic Research, Inc.
    5. Sofiya Avramova & Vanessa Le Leslé, 2012. "Revisiting Risk-Weighted Assets," IMF Working Papers 12/90, International Monetary Fund.
    6. Mitchell A. Petersen, 2009. "Estimating Standard Errors in Finance Panel Data Sets: Comparing Approaches," Review of Financial Studies, Society for Financial Studies, vol. 22(1), pages 435-480, January.
    7. Acharya, Viral V. & Schnabl, Philipp & Suarez, Gustavo, 2013. "Securitization without risk transfer," Journal of Financial Economics, Elsevier, vol. 107(3), pages 515-536.
    8. Sandra E. Black & Philip E. Strahan, 2002. "Entrepreneurship and Bank Credit Availability," Journal of Finance, American Finance Association, vol. 57(6), pages 2807-2833, December.
    9. Mariathasan, Mike & Merrouche, Ouarda & Werger, Charlotte, 2014. "Bailouts And Moral Hazard: How Implicit Government Guarantees Affect Financial Stability," CEPR Discussion Papers 10311, C.E.P.R. Discussion Papers.
    10. Mike Mariathasan & Ouarda Merrouche, 2012. "Recapitalization, credit and liquidity," Economic Policy, CEPR;CES;MSH, vol. 27(72), pages 603-646, October.
    11. Martin Hellwig, 2010. "Capital Regulation after the Crisis: Business as Usual?," ifo DICE Report, ifo Institute - Leibniz Institute for Economic Research at the University of Munich, vol. 8(2), pages 40-46, 07.
    12. Enrico Perotti & Lev Ratnovski & Razvan Vlahu, 2011. "Capital Regulation and Tail Risk," International Journal of Central Banking, International Journal of Central Banking, vol. 7(4), pages 123-163, December.
    13. Anat Admati & Martin Hellwig, 2013. "The Bankers' New Clothes: What's Wrong with Banking and What to Do about It," Economics Books, Princeton University Press, edition 1, number 9929.
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    15. Furlong, Frederick T. & Keeley, Michael C., 1989. "Capital regulation and bank risk-taking: A note," Journal of Banking & Finance, Elsevier, vol. 13(6), pages 883-891, December.
    16. repec:ces:ifodic:v:8:y:2010:i:2:p:14566986 is not listed on IDEAS
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    More about this item


    Basel II; capital regulation; internal ratings-based approach;

    JEL classification:

    • G20 - Financial Economics - - Financial Institutions and Services - - - General
    • G21 - Financial Economics - - Financial Institutions and Services - - - Banks; Other Depository Institutions; Micro Finance Institutions; Mortgages
    • G28 - Financial Economics - - Financial Institutions and Services - - - Government Policy and Regulation

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