Spread that solely mirrors credit risk
Based on historical data on defaults we can derive the fraction of the spread over riskless bonds for different rating classes and maturities, that is solely due to the probability of default and loss given default. The expected loss rate is derived from these two factors. Market participants who have a buy-and-hold perspective must decide on whether the current spread of a corporate bond sufficiently compensates for default and migration risk.
This is rather the perspective of a private than an institutional investor, because the latter in general has a short- to medium-term investment horizon and rarely holds a bond to maturity. In general, the institutional investor tries to achieve an excess return against a benchmark with a trading oriented management approach.
However, for the calculation of the required spread from a buy-and-hold perspective reliable default probabilities and recovery rates have to be used. If the issuer has an agency rating, Moody’s historical database is a good starting point. This database compiles expected default probabilities on a historical basis which is updated annually and also average recovery rates depending on the seniority of a bond. Those values allow to calculate a “fair” spread that solely mirrors credit risk.
One typical reason for spread differentials between bonds of the same rating are liquidity considerations, particularly with respect to stress situations. enerally, bonds with a large issue size, issued recently and actively traded by several market makers tend to be the most liquid. Sometimes old bonds with a small issue size, too, trade at rather tight levels. This is often the case for typical “CDO (Collateralized debt obligations) names”, that is bonds that are often included when CDOs are set up. Another reason for wide spread differentials between issuers with similar credit quality is that many market participants are concerned with potential mark-to-market losses. Therefore, rather illiquid and more volatile bonds require a higher spread, even if spread volatility is rather due to market technicals than uncertainty regarding company fundamentals. Consequently, it is natural that credit spreads differ even for bonds and issuers with the same rating.
One example from the automotive sector is the large spread differential between Ford and Renault bonds with similar coupon and maturity.