alternative methods.
Finally there is no agency that collects data on the characteristics of both ‘good’ and
‘bad’ borrowers, although some FIs are now keeping and sharing this information,
hence the development of better credit scoring models is hindered by a lack of data.
Lying on applications continues to be a problem. This requires verification of the
information provided.
Moody’s Analytics (KMV) credit scoring model:
The Moody’s model is based on option pricing. The common stock of a corporate
borrower can be viewed as a call option on firm value with an exercise price equal to the
book value of the firm’s debt. The ‘option’ feature is represented by the limited liability
of common stock. If the value of assets is less than the value of the debt the equity
holders default. This is equivalent to not exercising the option. If the value of the assets
at debt maturity is greater than the value of the debt, the stockholders (owners) exercise
the option on firm value by paying off the debt. Using the value of the stock, it is
possible to determine the underlying implied asset volatility and the market value of the
firm’s assets. With this data and the amount of debt, it is then possible to estimate the
probability that the call option winds up in the money (no default) or out of the money
(default). The probability of default is called the ‘expected default frequency’ or EDF.
Moody’s provides EDFs for 60,000 public companies (and many more private ones)
worldwide. Simulations have shown that the Moody’s model outperforms both the
Altman Z model and ratings changes by Standard & Poor’s.4 The Moody’s model will
normally predict changes in default probability ahead of ratings because the EDFs are
constructed using stock market data which is updated frequently whereas ratings
evaluations occur only at periodic intervals such as quarterly or annually. See for
instance Text Figure 20-2 for changes in bankruptcy probability for a sample firm.
In April 2009 the Credit Rating Agency Reform Act was passed. The act gives the SEC
regulatory authority over ratings agencies.
Teaching Tip:
Ratings agencies have an inherent conflict of interest that may prevent them from downgrading a
company as rapidly as firm or market conditions would imply; namely, the ratings agencies
receive substantial fees from the companies they rate. Empirical evidence has generally
concluded that market prices of securities reflect the changing bankruptcy probability
substantially sooner than ratings changes. For instance, Enron was downgraded, but continued to
be rated investment grade by Moody’s, S&P and Fitch as late as several weeks before it declared
bankruptcy. At the time, the stock’s price was trading at only $3 per share.5 It is increasingly
obvious that the business model used by ratings agencies needs to be fixed. In hindsight, the
ratings agencies appear to have been unduly influenced by security issuers and investment
bankers and/or have underestimated the riskiness of various firms and complex debt issues. The
4 For more information, see http://www.moodyskmv.com/.
5 See “Thoughts on Enron: What Happened, Why and How it Can Be Avoided Again,”
Testimony of Frank Partnoy, Financial Engineering News, June/July 2002.