Ben Bernanke\'s much-anticipated endorsement of more Federal Reserve stimulus Friday gave stocks a solid boost, though tempered by his picture of an economy that remains weak and vulnerable. At the close the Dow Jones Industrial Average was up 90.13 points (0.69 percent) at 13,090.84. The broad-based S&P 500 rose 7.09 (0.51 percent) to 1,406.57, while the tech-rich Nasdaq climbed 18.25 (0.60 percent) to 3,066.98. In his keenly awaited speech to central bankers, Bernanke warned that stagnation in the US labor market was \"a grave concern\" and signaled he would be pushing for more help for the economy when the Fed\'s policy board meets in 12 days.