The Dow Jones Industrial Average was down 13 points at 13,197, lifted by gains shares of Verizon Corp. and Intel Corp. .
But GM weighed on the blue-chip average, falling 3.2% after its quarterly results widely missed forecasts.
IBM , also in the Dow, gained 0.2% after saying it has used a nanotechnology process to make computer chips for the first time in a production setting, advancing the race to boost the power and energy efficiency of semiconductors.
The S&P 500 was up 1.1 points at 1,497, while the Nasdaq Composite rose 0.6 points to 2,558.
On Wednesday stocks rallied, lifting the Dow Jones Industrial Average to a record, thanks to deal speculation in the media sector, stronger-than-expected factory data, and Time Warner Inc.'s earnings report.
New data showing stronger-than-expected productivity and below-forecast labor costs were supportive of stocks. Strong productivity points to economic health while contained labor costs suggest that the Federal Reserve may be able to ease its monetary policy.
"We're looking at a higher opening," said Peter Cardillo, chief market economist at Avalon Partners. "It's obviously good news that wage pressure was contained. I think the catalyst today will be the economic numbers. So far we've had pretty good surprises, showing the economy growing at a moderate pace and escaping negative growth."
The Labor Department said productivity of the U.S. non-farm business sector rose at a 1.7% annual rate in the first quarter, well above a MarketWatch forecast of a 0.8% gain.
Unit labor costs - a key inflationary signal - rose at an annual rate of 0.6% in the first quarter. This was well-below expectations of a 2.1% increase.
In another sign of economic health, the department also said first-time claims for state unemployment benefits fell to their lowest level since early January, dropping by 21,000 to 305,000.
The Institute for Supply Management's April survey of the services sector also rose to a higher than expected reading of 56% in April from 52.4% in March. Economists expected the index to rise to 53.3%.
Stocks in motion
CBS Corp.'s quarterly profit fell 5.9%, although its adjusted earnings per share were a shade above analysts' expectations.
In other corporate news, Russia's Norilsk Nickel, the world's largest nickel producer, offered to buy Canada's LionOre Mining International for C$5.3 billion ($4.8 billion), or C$21.50 per share, in cash, seeking to break up Xstrata's agreement to buy the company. The offer price trumps Xstrata's offer of C$18.50 a share.
Treasury prices pared gains after the productivity report. The bond market responds positively to signs of contained inflation, but is made skittish by indications of strong productivity, which tend to diminish interest in low-risk assets.
The 10-year benchmark Treasury note last was up 1/32 at 99-27/32 with a yield of 4.648%.
The dollar pared some of its losses against the euro and yen after the data. Strong productivity enhances the dollar's attractiveness against its major rivals. The euro was last up 0.07% at $1.3599, while the dollar was down 0.02% at 120.16 yen.
Crude-oil futures were erratic, as news of fresh violence at oil installations in Nigeria offset some of the pressure from a U.S. supply report that showed a second weekly rise in crude inventories.
In addition, a fire forced the partial closure of an Exxon Mobil refinery with a capacity of 115,000 barrels a day. The June crude contract last was down 20 cents at $63.48 a barrel.
The June gold futures contract ros $2.90 to $678 an ounce.
By Leslie Wines