Global markets fall as Greece closes banks and twin defaults loom

Investors piled into U.S. Treasury bonds Monday as Greece's sovereign debt crisis escalated and sparked a broad selloff in global stock markets. Strong demand for haven assets sent the yield on the benchmark 10-year Treasury note to as low as 2.297% at 

Yanis Varoufakis REUTERS/Yves HermanGreek Finance Minister Yanis Varoufakis holds a news conference during a Euro zone finance ministers emergency meeting on the situation in Greece in Brussels, Belgium June 27, 

Banks all across Greece are closed today, and will remain closed for the rest of the week. Not because it's a holiday, but because the Greek government is trying to stop the banking system from collapsing as money flows out 

Yanis Varoufakis REUTERS/Yves HermanGreek Finance Minister Yanis Varoufakis holds a news conference during a Euro zone finance ministers emergency meeting on the situation in Greece in Brussels, Belgium June 27, 

At Saturday's meeting of Eurozone finance ministers it was decided to reject Greece's request for an extension of the current bailout until after the referendum, as such it will expire on 30 June. The ECB announced on Sunday that it will keep the