From late 2009, fears of a sovereign debt crisis developed among investors as a result of the rising government debt levels around the world together with a wave of downgrading of government debt in some European states. Concerns intensified in early 2010 and thereafter, leading Europe's finance ministers on 9 May 2010 to approve a rescue package worth €750 billion aimed at ensuring financial stability across Europe by creating the European Financial Stability Facility (EFSF). In October 2011 and February 2012, the eurozone leaders agreed on more measures designed to prevent the collapse of member economies. This included an agreement whereby banks would accept a 53.5% write-off of Greek debt owed to private creditors, increasing the EFSF to about €1 trillion, and requiring European banks to achieve 9% capitalisation. To restore confidence in Europe, EU leaders also agreed to create a common fiscal union including the commitment of each participating country to introduce a balanced budget amendment.

While sovereign debt has risen substantially in only a few eurozone countries, it has become a perceived problem for the area as a whole. Nevertheless, the European currency has remained stable. As of mid-November 2011, the euro was even trading slightly higher against the bloc's major trading partners than at the beginning of the crisis. The three countries most affected, Greece, Ireland and Portugal, collectively account for six percent of the eurozone's gross domestic product (GDP).