We analyze the determinants of the contribution of international banks to both global and local systemic risk during prominent financial crises. We find no empirical evidence supporting conjectures that bank size, leverage, non-interest income or the quality of the bank’s credit portfolio are persistent determinants of systemic risk across financial crises. In contrast, our results show that global systemic risk in particular is predominantly driven by characteristics of the regulatory regime. We also confirm for the subprime crisis that the banks’ contribution to moderately bad tail events in the past predicts the financial sector’s crash risk.

This paper analyzes the systemic risk effects of bank mergers to test the “concentration-fragility” hypothesis. We use the marginal expected shortfall as well as the lower tail dependence between a bank’s stock returns and a relevant bank sector index to capture the merger-related change in an acquirer’s contribution to systemic risk. In our empirical analysis of a dataset of international domestic and cross-border mergers, we find clear evidence for a significant increase in the merging banks’, the combined banks’ as well as their competitors’ contribution to systemic risk following mergers, thus confirming the “concentration-fragility” hypothesis.