Credit Ratings and Credit Risk: Is One Measure Enough?

58 Pages Posted: 18 Sep 2009 Last revised: 5 Aug 2015

Jens Hilscher

University of California, Davis

Mungo Ivor Wilson

University of Oxford - Said Business School

Date Written: July 24, 2015

Abstract

This paper investigates the information in corporate credit ratings. If ratings are to be informative indicators of credit risk they must reflect what a risk-averse investor cares about: both raw default probability and systematic risk. We find that ratings are relatively inaccurate measures of raw default probability - they are dominated as predictors of failure by a simple model based on publicly available financial information. However, ratings do contain relevant information since they are related to a measure of exposure to common (and undiversifiable) variation in default probability ('failure beta'). Systematic risk is shown to be related to joint default probabilities in the context of the Merton (1974) model. Empirically, it is related to CDS spreads and risk premia. Given the multidimensional nature of credit risk, it is not possible for one measure to capture all the relevant information.

Keywords: credit rating, credit risk, default probability, forecast accuracy, systematic default risk

JEL Classification: G12, G24, G33

Suggested Citation

Hilscher, Jens and Wilson, Mungo Ivor, Credit Ratings and Credit Risk: Is One Measure Enough? (July 24, 2015). AFA 2013 San Diego Meetings Paper. Available at SSRN: https://ssrn.com/abstract=1474863 or http://dx.doi.org/10.2139/ssrn.1474863

Jens Hilscher (Contact Author)

University of California, Davis ( email )

One Shields Avenue
Davis, CA 95616
United States

Mungo Ivor Wilson

University of Oxford - Said Business School ( email )

Park End Street
Oxford, OX1 1HP
Great Britain
+44 (0) 1865 288914 (Phone)

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