This article compares the linkages between credit fundamentals, ratings and value-at-risk measures for CDO tranches with those for corporate bond exposures. A sensitivity analysis incorporating market information and rating migrations data reveals that the behaviour of CDO tranche ratings can differ markedly from that of corporate ratings. In addition, tranching is found to have an important impact on the probability of large losses. This highlights how investors who narrowly focus on ratings and draw direct parallels with corporate exposures can seriously misjudge the value-at-risk of CDOs.
JEL classification: G24, G32.