The rating agencies have been criticized for being too slow to react to changes in the credit quality of an issuer, leading to serially correlated rating patterns and limiting the value of ratings as a risk management tool. As a reaction, Moody’s decided to put its rating process under review, and acquired KMV to be able to provide investors with additional, marketbased assessments of an issuer’s credit quality. The feedback from market participants was surprising. Since investors themselves tend to use spreads and spread volatility as indicators for credit risk, the vast majority does not want Moody’s or the other rating agencies to switch to a more marketbased approach when assessing the credit quality of an issuer. There is really a need for, according to the feedback, more transparency with regard to the rating process. This would allow investors to use rating agency information in their risk management most efficiently.

For purposes of risk management bonds are often grouped according to agency ratings based on the assumption that bonds with similar ratings tend to show a high degree of comovement. Breger et al. (2003) examine whether the correlation between individual bonds increases if they are grouped by implied ratings, that is by spread classes rather than by agency ratings. The rationale for this would be that market valuations are a better indicator for the drivers of credit spread changes, namely perceived credit quality and risk exposure, than are agency ratings. In their empirical study they find that bonds of the same spread class are more similar than bonds with the same rating from a risk/return perspective. Breger et al. (2003) conclude that the classification of bonds based on market data provides a more reliable basis for modeling return relationships than does a classification by agency ratings. However, one has to note that the motivation behind this study differs significantly from the rating agencies’ approach. The objective is not to predict default risk, but rather to improve the classification of corporate borrowers and provide a basis for reliable spread risk forecasts.

A strong negative correlation between default rates and economic growth could always be expected, but during the economic crisis in the United States in the 1970s and 1980s a sharp increase of the default rates could not be observed. It was the economic slowdown in 1990, which was accompanied by extremely increasing default rates. The same acceleration of default rates occurred in 2001 due to a prolonged downturn of the economy, high political uncertainty after September 11, 2001, company accounting scandals, and aggregate weak credit fundamentals. Structural changes in the credit markets can explain the weaker than assumed relationship between the default rates and the economic cycle. This leads to the conclusion that the relationship between default rates and the spread level in the corporate bond market is a very complex one and that a good performance in the corporate bond market (tightening of credit spreads) can be consistent with increasing default rates at times where the market anticipates future decreasing default rates.

The following paragraph will deal with default rates because they are of central importance for high-yield investors. We compare the three major default peaks since 1920. Default rates have to be distinguished between “issuer-weighted” and “dollar-weighted”. The increasing amount of Fallen Angels in 2002 resulted in a sharp increase of the “dollar-weighted” default rate.

High-yield spreads tend to lead default rates, which means that a tightening will occur prior to a fall in the default rate because market participants will already anticipate the future development of the default rate. This relationship broke down in 2002 for a couple of months due to the large divergence of the “dollar-weighted” from the “issuer-weighted” default rate. As we can see cumulative default rates tend to increase progressively with a decreasing rating class.

Interestingly, the relationship between equity and bond markets differs in deflation-risk periods and inflation-risk periods. In inflation-risk periods, rising inflation rates push up long-term interest rates, reflecting the fear that aggressive monetary tightening will depress future earnings and hence stock prices. Thus, in periods of rising inflation risk, government bond prices and stock prices tend to fall. In deflation-risk periods government bond prices and stock prices usually go in opposite directions, because fixed income markets benefit from the expectation of falling interest rates, while equities suffer from the worsening profit outlook and increasing default risk. Credit spreads tend to benefit from rising inflation because it becomes easier for companies to pay down their debt.

Deflationary periods usually lead to a spread widening across the whole credit market, hitting consumer-related industries the hardest. However, long-term interest rates seem to have a minor influence on fluctuations of credit spreads in the short term. Companies that borrow at a fixed rate are immune to changes in yields and spreads over the life of the borrowing. Yet, there is a refinancing risk, when debt has to be rolled over. Conversely, when companies borrow at floating rates, they are directly affected by changes in money market rates, which are primarily driven by monetary policy.