U.S. stocks rallied on Friday to close a second straight week of gains on hopes of collective action from global central banks if Sunday's election in Greece triggers market turmoil.

The Dow Jones industrial average rose 115.26 points, or 0.91%, to end unofficially at 12,767.17. The S&P 500 Index gained 13.73 points, or 1.03%, to finish unofficially at 1,342.83. The Nasdaq Composite added 36.47 points, or 1.29%, to close unofficially at 2,872.80.