This study conducts a comprehensive analysis of the economic benefits and costs of credit default swap (CDS) in credit markets since its inception. Consistent with its role of insuring credit risk, the introduction of CDS reduces illiquidity and liquidity risk more for speculative grade bonds with high credit risk than investment grade ones. More importantly, CDS significantly improves the price convergence between investment grade bonds and CDS spreads through a popular trading strategy—CDS-bond basis arbitrage in normal period. In the recent crisis, however, CDS fails to reduce the prolonged price divergence between the two markets plausibly due to the lack of arbitrage. Overall, the economic impact of CDS is dependent on the prevailing trading strategies in the credit markets