The S&P remains near its highest intraday level in more than five years.
Equities have been strong performers of late, buoyed largely by healthy growth in corporate earnings, with the S&P 500 gaining 6.5 percent so far this year. The Dow opened higher in early trading before sliding into negative territory.
While analysts continue to see an upward bias in markets, recent daily moves have been small and trading volumes have been light.
"There is a general upward bias, but right now we're at the top of the range we've been in, so we could struggle to advance further," said Paul Nolte, managing director at Dearborn Partners in Chicago.
The S&P 500 was well over its 50-day moving average of 1,460.92, a sign the market could be overbought.
Comcast Corp agreed late Tuesday to buy General Electric Co's remaining 49 percent stake in NBC Universal for $16.7 billion. Comcast jumped 6.3 percent to $41.41 as the S&P's top percentage gainer while Dow component GE was up 3 percent to $23.26.
Deere & Co reported earnings that beat expectations and raised its full-year profit outlook. After initially rallying in premarket trading, the stock fell 0.9 percent to $93.12.
According to the latest Thomson Reuters data, of the 353 companies in the S&P 500 that have reported results, 70.3 percent have exceeded analysts' expectations, above a 62 percent average since 1994 and 65 percent over the past four quarters.
Fourth-quarter earnings for S&P 500 companies are estimated to have risen 5.3 percent, according to the data, above a 1.9 percent forecast at the start of the earnings season.
The S&P was mere points away from 1,523.57, which would represent the index's highest intraday level since November 1, 2007.
Industrial and construction shares will be in focus following President Barack Obama's State of the Union address on Tuesday, during which he called for a $50 billion spending plan to create jobs by rebuilding degraded roads and bridges. He also backed higher taxes on the wealthy.
Yahoo Inc Chief Executive Marissa Mayer said Tuesday the company's search partnership with Microsoft Corp was not delivering the market share gains or the revenue boost that it should.
Retail sales rose 0.1 percent in January, as expected, as tax increases and higher gasoline prices restrained spending. Equities were little impacted by the data.