Effect of signals of bank ratings on stock returns before and during the financial crisis

This paper analyses the effect of rating signals on banks' stock market returns during the period 2004-2012. The results obtained show that investors respond to rating announcements. Specifically, it is found that before the financial crisis, positive rating signals issued by Standard and Poor's and Moody's, and negative ratings signals issued by Fitch and Standard and Poor's, have a significant effect on the return on banks' shares. Conversely, in a context in which the banks experienced a significant worsening of their financial situation and the rating agencies were in the spotlight, investors reacted not only to rating downgrades as expected, but also to rating upgrades. Furthermore, the results suggest that investors do not react with the same intensity to the ratings signals issued by the rating agencies. Analysis of the causal relationship between rating signals and returns on banks' shares indicates that the policies of the rating agencies are not totally independent of changes occurring in the financial markets.