Since May 2010, the country has survived on billions in rescue loans from the other 16 eurozone countries and the International Monetary Fund. In return, it raised taxes and slashed wages and benefits, driving hundreds of thousands into poverty.
Last week, the government bought back a large slice of its debt held by private sector investors, scratching some â¿¬20 billion ($26.4 billion) off the national debt.
The ratings agency Standard & Poor's on Tuesday upgraded Greece's credit grade by 6 notches, from default to the B- junk rating.
The action spurred a bank-led rally on the Athens Stock Exchange Wednesday, with shares up nearly 3 percent at 862.88 in afternoon trading.