Wall St ends up

U.S. stocks finished higher in volatile trading on the final day of the month, after Fed Chairman Bernanke kept door open for further economic stimulus.
All three major averages also logged their first August gains since 2009
The Dow Jones Industrial Average jumped 90.31 points to close at 13,090.84.
The S&P 500 climbed 7.10 points to finish at 1,406.47, while the Nasdaq composite gained 18.25 points to end at 3,066.96.