Rating downgrade and the price impact of CDS spread on stock return

We investigate the time-varying informativeness of credit default swap (CDS) trading on stock returns for 302 US firms from July 2004 to August 2010. Using the Acharya and Johnson (2007) measure, we find that CDS trading becomes informative for an increasing number of firms as we approach the global financial crisis (GFC). Firm numbers gradually decline post-GFC, but remain high compared to the pre-GFC period. furthermore, CDS trading imposes the largest conditional price impact on firms that are recently downgraded, regardless of rating levels. Interestingly, this holds during and after the GFC, but not before. We offer two implications. First, despite post-GFC outcry against the CDS market, our results suggest it exhibits enhanced price discovery during the GFC. Second, our findings support criticism that, in the lead-up to the GFC, rating agencies are slow in downgrading firms. However, if downgrade decisions made during and after the GFC induce informed trading in the CDS market, this necessarily implies that during the midst of the GFC, rating agencies have got their act together.