Considering the importance of dynamic credit risk modeling, the analysis of the relationship between the two major indicators for credit risk, that is default rates and credit spreads, and the business cycle is central for the understanding of the risks associated with investing in corporate bonds. Especially investors that tend to hold securities to maturity, investing in high yield, or running structured portfolios are concerned about avoiding defaults. While default rates generally are a function of the credit cycle outlined above, their current level is not necessarily reflected in credit spreads. In order to judge the attractiveness of the current spreads, one need to not only forecast the future direction of default rates, but also to see whether they are sufficient to cover potential future losses. The sensitivity of the corporate bond market to economic downturns depends particularly on the distribution of the credit quality of the issuers and on the ratio of cyclical companies to noncyclical companies.