People wait outside a closed branch of Piraeus Bank in Athens, Greece

Mario Draghi , head of the European Central Bank

People wait outside a closed branch of Piraeus Bank in Athens, Greece June 27, 2015. The specific branch opens at 10:30 AM local time on Saturdays but it remained closed whille dozens of people lined outside to withdrew cash. A senior Greek politician on Saturday issued an assurance that banks would remain open and asked people to remain calm, hours after Prime Minister Alexis Tsipras announced a surprise referendum on bailout terms offered by foreign creditors. REUTERS/Yannis Behrakis