The article explores how default contagion affects the pricing of portfolio credit derivatives. By using a model with constant default intensities that can jump at default times, the researchers were able to calculate credit default swap spreads and kth-to-default swap spreads. They found that the amount of default interaction impacts spreads, market CDS prices influence kth-to-default spreads, recovery rates affect portfolio comparisons, and non-symmetric portfolios can be approximated by symmetric ones.