The S&P 500 closed flat on Wednesday as a mixed bag of corporate earnings failed to give investors the confidence to push equities higher with the index near record levels.

For the second day in a row, the Dow posted outsized losses following weak results from one of its components while the Nasdaq climbed, with BlackBerry one of its biggest boosts.

International Business Machines lost 3.3 per cent to $US182.25, the biggest drag on the Dow after the tech giant missed revenue expectations for a fourth straight quarter amid weakening demand, particularly in growth markets like China.

The results followed disappointments from Verizon, Travelers and Johnson & Johnson, which weighed on the blue-chip index on Tuesday.

IBM's decline offset modest gains from fellow component United Technologies Corp, which rose 1 per cent to $US116.12 after it reported fourth-quarter earnings that topped Wall Street estimates, although revenue was shy of expectations.

"We've seen significant decreases in a company's ability to deliver on earnings this quarter ... however, we've also seen signs that the top-line growth we've been looking for is starting to emerge," said Kristina Hooper, head of portfolio strategies at Allianz Global Investors in New York.

"Seeing a broad-based top-line growth trend would really speak to the health of the economy ... that's allowed for the market to hang in there despite some disappointments."

With 16 per cent of the S&P 500 having reported, about 61 per cent have topped profit expectations, according to Thomson Reuters data, compared with the average of 67 per cent over the past four quarters. More than 66 per cent have topped revenue expectations, above the 55 per cent average over that timeframe.

About eight companies have issued negative outlooks for every positive one, which would mark the lowest ratio on record should it continue.

After the market closed on Wednesday, Netflix Inc reported a rise in fourth-quarter earnings, helped by subscriber growth. Shares surged 17 per cent in after-hours trading.

Online auction site eBay Inc surged 11 per cent to $US60.44 after the bell following its results.

The Dow Jones industrial average was down 41.10 points, or 0.25 per cent, at 16,373.34. The Standard & Poor's 500 Index was up 1.06 points, or 0.06 per cent, at 1,844.86. The Nasdaq Composite Index was up 17.24 points, or 0.41 per cent, at 4,243.00.

After a 29.6 per cent jump in 2013, buoyed by the Federal Reserve's massive stimulus, the S&P 500 is down 0.2 per cent this year as investors look to corporate profits to justify current prices. The index is 0.2 per cent away from its all-time closing high.

"In general, valuations are stretched, though there are still areas of opportunity for investors who are able to be more selective," said Hooper, who helps oversee $US436 billion in assets under management. "Focusing on areas with more growth may be worth paying up for."

Also in earnings, Advanced Micro Devices slumped 12 per cent to $US3.67 after forecasting a steeper-than-expected fall in current quarter revenue, while Coach Inc tumbled 6 per cent to $US49.38 as the S&P's worst performer after it said sales in North America fell further in the final quarter of 2013.

On the upside, Norfolk Southern Corp jumped 4.8 per cent to $US92.94 after its earnings beat expectations, helping lift the Dow Jones Transportation average to a record high.

Nuance Communications rose 7.8 per cent to $US16.05 after giving a first-quarter outlook, helping to boost the Nasdaq. US-listed shares of BlackBerry also buoyed the tech-heavy index, jumping 8.6 per cent to $US10.78. Shares of the smartphone maker are up about 26 per cent over the past three sessions.

About 62 per cent of companies traded on the New York Stock Exchange closed higher while 55 per cent of Nasdaq-listed shares ended in positive territory. About 6.23 billion shares traded on all US platforms, according to BATS exchange data.

Reuters