Credit ratings

Via Mark Thoma Economist’s View comes this note on credit rating company incentives:

While the US Department of Justice did not give any statistical evidence in its deposition, our new research (Efing and Hau 2013) suggests that rating favors were indeed systematic and pervasive in the industry.

In a sample of more than 6,500 structured debt ratings produced by Standard & Poor’s, Moody’s and Fitch, we show that ratings are biased in favor of issuer clients that provide the agencies with more rating business. This result points to a powerful conflict of interest, which goes beyond the occasional disagreement among employees.


Additional evidence for rating bias emerges for bank ratings. Hau, Langfield and Marques-Ibanes (2012) show in a paper forthcoming in Economic Policy that rating agencies gave their largest clients also more favorable overall bank credit ratings. …

Hau, Langfield and Marqués-Ibañez (2012) also show that large banks profited most from rating favors. … The rating process for banks may have contributed to substantial competitive distortions in the banking sector, thus fostering the emergence of the too-big-to-fail banks


The lawsuit against Standard & Poor’s highlights the conflicts of interest inherent in the rating business, but can do little to resolve them. If new and complex regulation and supervision of rating agencies provides a remedy is unclear and remains to be seen. However, three alternative policy measures could make the existing conflicts much less pernicious:

  • Similar to US bank regulation under the Dodd-Frank act, Basel III should abandon (or at least decrease) its reliance on rating agencies for the determination of bank capital requirements.
  • As forcefully argued by Admati, DeMarzo, Hellwig and Pfleiderer (2011), much larger levels of bank equity as required under Basel III could reduce excessive risk-taking incentives and ensure that future failures in bank-asset allocation do not trigger another banking crisis.
  • More bank transparency in the form of a full disclosure of all bank asset holdings at the security level would create more informative market prices for bank equity and debt, with positive feedback effects on the quality of bank governance and bank supervision.

Our reliance on bank ratings could thus be greatly reduced. …

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