Before the European Central Bank assumes its role as ultimate bank supervisor of the Banking Union in November 2014, it is to subject the 128 largest system-relevant banks in the Eurozone to a comprehensive balance sheet review. The IW Bank Monitor has been developed to provide ongoing scientific assessment of the consolidation process in the banking sector and the establishment of the Banking Union. The analyses indicate that, while the majority of the banks under scrutiny are stable, a limited few must be assumed to have considerable problems. If a further crisis of confidence is to be avoided, the European Central Bank should already be communicating its strategies for tackling these problems.