Wall St gains on Yellen comments and Yahoo
Data showing Chinese economic growth exceeded expectations and US industrial production rose for a second straight month also improved sentiment, though Bank of America and CSX Corp sold off following their results.
Yellen, speaking in New York, reaffirmed the Fed's commitment to keep interest rates low, even after ending its bond-buying program, as long as inflation remains below target and unemployment elevated.
The Fed's Beige Book, a report of anecdotal information on business activity, showed that activity picked up in most regions in recent weeks.
Yahoo was the S&P 500's biggest gainer, rising 6.3 percent to $36.35. While the company gave a tepid revenue outlook, revenue growth accelerated in the last quarter of 2013 for Alibaba , in which Yahoo holds a 24 percent stake.
The Dow Jones industrial average rose 162.29 points, or 1.00 percent, to end at 16,424.85.
The Standard & Poor's 500 Index gained 19.33 points, or 1.05 percent, to finish unofficially at 1,862.31.
The Nasdaq Composite Index jumped 52.06 points, or 1.29 percent, to close at 4,086.23.
MSCI's all-country world index rose 1.02 percent, while the FTSEurofirst 300 index of leading European shares closed up 1.2 percent at 1,322.51 points. Yet many traders pegged the gain as a technical rebound after a 1 percent decline in the previous session.
The euro rose 0.01 percent to $1.3813. There were also more bond gains for former trouble spots Italy, Spain, Portugal and Greece. The 10-year US Treasury note slipped 1/32 of a point in price, boosting its yield to 2.6337 percent, as the growth in China reduced demand for safe-haven government bonds.
Global oil prices rose close to $110 a barrel but gave up some gains after an unexpectedly large build in crude stocks in the United States, the world's largest consumer of oil.
Brent crude for June delivery rose by a dollar earlier in the session but pared gains to settle up 24 cents at $109.60 a barrel.
US crude for May delivery also rose more than $1 before paring gains immediately after closely watched data form the US Energy Information Administration was released. US crude settled 1 cent higher at $103.76 a barrel.
Crude oil stocks rose 10 million barrels to 394 million barrels in the week ending April 11, according to the EIA data, far more than the 2.3 million-barrel build expected by analysts.