Dynamic Correlations of Sovereign Bond Yield Spreads in the Euro zone and the Role of Credit Rating Agencies' Downgrades

The European debt crisis that followed the global financial crisis, erupting first with Greece, then Ireland, Portugal, Italy and Spain, has threatened the very existence of the Euro zone. In this paper we examine the evolution of dynamic co-movements of sovereign bond yield spreads (BYS) in the Euro zone and the role of credit rating agency downgrades on those co-movements. Estimation results from a multivariate DCC-GARCH model on daily BYS data for nine Euro zone countries over the period 2007-2012 suggest an inverted U-shaped curve of BYS co-movements during the period of the financial and debt crisis. Credit rating downgrades by major rating agencies indicate rather idiosyncratic patterns of government bond yield spreads co-movements within and between the Euro zone periphery and the core.