Tensions grew with the bursting of the property bubble and the consequent disruption of banking in Ireland. With the announcement of the involvement of private investors in restructuring Greek debt in the summer of 2011, financial markets suddenly became aware of the implications of the ban on interventions to rescue member states under the Treaty on European Union.
There followed a very serious crisis of confidence in the ability of the single currency to survive, with negative consequences for the real economies of individual countries and for the area as a whole. The list of potential causes of the crisis is rather crowded.