Low aggregate bank profitability in the euro area, which weakens the resilience of the euro area banking sector, is partly explained by the persistent underperformance of a sub-set of banks. These banks all stand out in terms of elevated cost-to-income ratios. But there also appear to be three distinct groups: (i) banks struggling with legacy asset problems; (ii) banks with weak income-generation capacity; and (iii) banks suffering from a combination of cost and revenue-side problems. The common cost inefficiency problem seems most pronounced for the largest and smallest banks. Three strategies, all of which should reduce overcapacity, could address the root causes, while avoiding increasing market power or the systemic footprint of institutions which are already systemically important. For some banks, the focus should be on targeting continued high stocks of NPLs. But in systems with many weak-performing small banks, consolidation within their domestic system could improve performance. Finally, a combination of bank-level restructuring and cross-border M&A activity could help reduce the costs and diversify the revenues of large banks that are performing poorly.