Sovereign and Bank Contagion in the Eurozone: A Multi-Scale Approach using Wavelet-Network Analysis

This study establishes time-frequency networks of sovereign and bank contagion in the eurozone over the period 2009-2021. By applying discrete wavelet transformation, daily CDS premia of sovereigns and banks are decomposed into multi-horizon components to specify directed and dependence-weighted networks. Dynamic analysis shows that the network connectivity and the strength of the dependencies are significantly lower after the introduction of the European Banking Union in 2014. While the strength effect is pronounced across all time horizons, the network connectivity only reduces in the short and medium run. This provides evidence that the new regulatory framework promotes financial stability but is more effective in the short and medium horizons. The consideration of the COVID-19 pandemic as a real-life stress test confirms these findings as the strength of the dependencies keeps at significantly lower levels.