Yellen, 67, delivered her first public remarks as Fed chairman as policy makers pursue plans to gradually scale back the unprecedented bond-purchase program she helped put in place. She repeated the Fed's outlook for further reductions in "measured steps" and that asset purchases, known as quantitative easing, are not on a "pre-set course."

'Dual mandate'

While growth has picked up, "the recovery in the labor market is far from complete," Yellen said in the text of remarks to the House Financial Services Committee. "I am committed to achieving both parts of our dual mandate: helping the economy return to full employment and returning inflation to 2 percent while ensuring that it does not run persistently above or below that level."

Federal Open Market Committee officials have twice reduced the size of the monthly asset-purchase program, lowering bond buying to $65 billion in February from $85 billion last year. Three rounds of stimulus have helped push the S&P 500 as much as 173 percent higher from a 12-year low in 2009.

The S&P 500 last week posted its biggest weekly advance this year amid speculation that economic growth is robust enough to weather slower stimulus from the Fed even as data showed weaker-than-forecast hiring. The benchmark index has rallied 3.6 percent over the past six sessions, trimming its decline for the year to 2.3 percent.

Economic growth

The S&P 500 closed at a record on Jan. 15 and then dropped 5.8 percent through Feb. 3 amid signs of slowing growth in China and a rout in emerging-market currencies.

The central bank is studying employment and other economic data to determine when next to taper its stimulus measures. The Labor Department's report on Feb. 7 showed payrolls rose by a less-than-projected 113,000 in January, while the unemployment rate dropped to the lowest level in more than five years.

Investors are also awaiting financial results today from 16 companies in the S&P 500. Of the index members to have reported this season, 76 percent beat analysts' profit estimates, while 66 percent exceeded sales forecasts, data compiled by Bloomberg show.

Profit for the benchmark's stocks rose by 8.3 percent in the fourth quarter of 2013 and revenue by 2.7 percent, according to analyst estimates compiled by Bloomberg.

Sprint jumped 7.1 percent to $8.24 after saying fourth- quarter sales rose to $9.14 billion, beating the average analyst estimate calling for $8.99 billion in a Bloomberg survey.

CVS Caremark

CVS Caremark added 2.6 percent to $68.70. The largest provider of prescription drugs in the U.S. posted fourth-quarter profit that topped analysts' estimates. The new drugs and an expanded roster of clients for specialty pharmaceuticals, along with higher prices, boosted revenue from pharmacy services to $19.6 billion, the company said.

InvenSense climbed 11 percent to $21.70 after entering into a patent cross-license agreement with STMicroelectronics, resolving lawsuits over infringement. Neither company admitted to any liability in the dispute over micro-electro-mechanical systems, or MEMS, which incorporate motion sensors and are used in cameras, fitness equipment, smartphones, remote controls and other devices.

General Motors Co. gained 1.8 percent to $35.51 as sales in China rose 12 percent to a record 348,061 units last month. Buick monthly deliveries gained 16 percent to surpass 100,000 units for the first time.

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