S&P cut Greece's rating to SD at the end of February, following a deal the country made to reduce its debts.

According to a press release issued by S&P on Wednesday, the upgrade results from Greece’s successful $172 billion bond swap offer, completed on April 25.

“The 'CCC' rating on Greece reflects our view of the recent reduction in government debt following the restructuring, the reduction in debt servicing costs as a result of the exchange, and the increased average maturity of the central government debt stock,” S&P wrote in the release.

S&P forecasts the Greek economy will shrink by a further 5 percent in 2012, having shrunk 6.9 percent in 2011.