The pricing of portfolio credit risk

Equity and credit-default-swap (CDS) markets are in disagreement as to the extent to which asset returns co-move across firms. This suggests market segmentation and casts ambiguity about the asset-return correlations underpinning observed prices of portfolio credit risk. The ambiguity could be eliminated by – currently unavailable – data that reveal the market valuation of low-probability/large-impact events. At present, judicious assumptions about this valuation can be used to reconcile observed prices with asset-return correlations implied by either equity or CDS markets. These conclusions are based on an analysis of tranche spreads of a popular CDS index, which incorporate a rather small premium for correlation risk.