Global ratings agency Moody's upgraded Greece's rating to "Baa3" from "Ba1" on Friday, citing quicker-than-expected improvement in public finances and the country's greater resilience to potential future shocks. "Based on the government's policy stance, institutional improvements that are bearing fruit, and a stable political environment, we expect Greece to continue to run substantial primary surpluses, which will steadily decrease its high debt burden," Moody's said in a statement.