Weekly jobless claims unexpectedly gained 10,000 last week to a seasonally adjusted 354,000, according to the Labor Department. Economists surveyed by Reuters expected a reading of 340,000. But a Labor Department analyst said claims for five states, including Virginia, Minnesota and Oregon, were estimated since state offices had less time to prepare data because of the Memorial Day holiday on Monday.
Meanwhile, the four-week moving average for new claims edged up 6,750 to 347,250.
And the U.S. economy grew at a 2.4 percent annual rate in the first three months of the year, according to revised numbers from the Commerce Department, falling slightly short of estimates for a 2.5 percent gain.
Also on the economic front, pending home sales for April is scheduled to be released at 10 am ET.
Futures were lower earlier after Japan's Nikkei index plummeted over 5 percent, weighed down by the strengthening yen and volatile Japanese government bond yields.
(Read More: Sun Will Rise: Investors Still Love Japan)
Additionally, investors remained sensitive to the notion that the Fed could soon begin to pull back on its massive unlimited stimulus. Analysts took heart on Wednesday in the comments of Boston Fed President Eric Rosengren, one of the central bank's most vocal proponents of accomodative monetary policy, who said the Fed should continue to flood the economy with more stimulus until the recovery becomes "self-sustaining" and labor markets thaw.
"We do not believe key members of the FOMC have already made up their minds on what the next change in Federal Reserve policy should be," said Nomura analysts in a research note. "Any decision to change the pace of asset purchases will depend on how economic data and financial markets evolve."
Dish Network sweetened its buyout offer for Clearwire Corp to $4.40 per share, valuing the wireless service provider at $6.5 billion and topping a rival bid by Sprint Nextel by nearly 30 percent.
Meanwhile, MidAmerican, a unit of Warren Buffett's Berkshire Hathaway, said it will pay $5.6 billion for NV Energy, the electric utility serving Las Vegas and its casinos.
In another light day of earnings, Costco edged higher after the warehouse club chain posted earnings that edged past expectations, thanks to low prices for food and gasoline.
Big Lots tumbled after the discount retailer handed in current-quarter and full-year guidance that fell short of expectations.
Joy Global declined after the mining equipment maker reported lower quarterly results and slashed its full-year earnings outlook, hurt by a drop in commodity prices.
Lions Gate Entertainment and Splunk are among notable companies scheduled to post earnings after the closing bell.
Facebook rallied after BMO upgraded the social networking giant to "outperform" from "market perform" and Jefferies lifted its rating on the company to "buy" from "hold."
Moody's Investors Service downgraded aluminum producer Alcoa to junk grade, citing weak aluminum prices and tough market conditions.
The Treasury is scheduled to auction $29 billion in 7-year notes with the results available shortly after 1pm ET.