Stocks added to gains on Thursday after the board that sets U.S. accounting standards agreed to give banks more flexibility in applying mark-to-market accounting to their toxic assets.

Optimism was also boosted as leaders of the G20 nations agreed to put an additional trillion dollars into the ailing global economy through extra funding for groups like the IMF.

The Dow Jones industrial average <.DJI> climbed 275.02 points, or 3.54 percent, to 8,036.62. The Standard & Poor's 500 Index <.SPX> rose 30.46 points, or 3.76 percent, to 841.54. The Nasdaq Composite Index <.IXIC> jumped 64.06 points, or 4.13 percent, to 1,615.66.

(Reporting by Leah Schnurr; Editing by James Dalgleish)