Measuring sovereign bond fragmentation in the Eurozone

Fragmentation in the sovereign bond market of the Eurozone involves divergences in borrowing costs and undermines the stability of the monetary union. In this paper, we propose an indicator of fragmentation between government bonds of the core and peripheral European countries. Using a regime-switching cointegration model, we identify the absence of fragmentation as periods where the bond yields of the two groups share a common stochastic trend in the long-run. The results show that the indicator of fragmentation is responsive to systemic stress events and is negatively related to the ECB’s monetary policy actions.