The euro area financial system took excessive risks during the global credit boom, which in some countries led to an unsustainable increase in credit, higher asset prices and housing booms. This process helped to fuel large imbalances within the euro area. Banks played a key role in channelling funds from economies with large surpluses to deficit countries, leading in some cases to the accumulation of considerable risks for borrowers and lenders. Weaknesses in the regulatory and supervisory architecture contributed to these problems in the euro area, as in other OECD economies. Gaps in microprudential regulation created an environment prone to excessive risk-taking: capital buffers were too small; the quality of capital was inadequate; banks’ models underestimated risks; and risks were shifted off-balance sheet and beyond supervisory oversight. Liquidity risks were not adequately monitored. Systemic risks were allowed to build up as the authorities largely failed to counter the credit cycle. Some large systemic banks contributed to growing imbalances and vulnerability. The decentralised European supervisory architecture was not sufficiently effective in supervising large cross-border institutions. When the financial crisis hit, the co-ordination of cross-border rescues proved problematic and complicated efficient resolution. Stronger regulations are needed to improve financial stability. Effective microprudential regulation is the first line of defence. This should be upgraded by implementing the Basel III capital accord, as has been announced by the EU authorities, and a range of related measures. Some consideration should be given to an accelerated phasing-in. Macroprudential regulation should be significantly developed to mitigate pro-cyclicality and reduce systemic risks posed by large cross-border banks. The creation of the European Systemic Risk Board is welcome. To improve cross-border supervision, the European Banking Authority should have sufficient powers and resources to ensure that a system based on national supervision leads to coherent regulation and effective supervision. In addition, a cross-border crisis-management framework for Europe is needed. Overall, significant steps have already been taken by the EU authorities to address these issues and further reforms are under way. This working paper relates to the 2010 OECD Economic Survey of the Euro area. (www.oecd.org/eco/surveys/EuroArea).