The Dow Jones industrial average closed up 115 points on Friday. Investors expect that the central banks of countries around the world stand ready to head off a deeper European debt crisis.
Greece holds a crucial election on Sunday that will help determine whether that country abandons the euro.
The Dow finished at 12,767. That's a one-month high. The Standard & Poor's 500 index ended 13 points higher at 1,342. The Nasdaq composite index closed up 36 at 2,872.
Trading volume was about average, 4.1 billion shares. Advancing stocks outpaced declining stocks by more than 4-to-1.