The outbreak of the financial crisis after the fall of Lehman Brothers brought a pressing need to bail out financial institutions in order to avoid systemic risk and to ensure financial stability. The Commission issued then four communications in order to address these problems and reopen the flow of credit into the real economy. The State aid regime principles for regular ailing firms were used to prevent moral hazard issues and to safeguard competition. This paper goes through the main characteristics of the State aid policy towards financial institutions applied by the Commission during the crisis, assessing it effectiveness to fight the pernicious effects of the crisis while maintaining the level playing field in the financial markets. I conclude that State aid has not been perfectly effective in solving problems and that it has been used for purposes different to those for which it was conceived, just because it is was the only and imperfect tool to manage the crisis from a European level, taking into account the cross-border effects that State aid entails.