Stock index futures jumped on Wednesday after better-than-expected data out of China and Germany and as Greece inched closer to a debt deal, but recent market action suggested gains could be ephemeral.

Volatility was seen persisting, with low trading volume and mixed corporate earnings adding to the uncertainty.

China's factory sector expanded slightly in January, confounding expectations for a contraction and supporting hopes the world's second biggest economy will avoid a hard landing. Separately, Germany recorded its first rise in manufacturing output in seven months.

Greek Finance Minister Evangelos Venizelos said talks between Greece and its private creditors were one formal step away from a deal needed to avoid a messy default.

Not only was the economic data out of Europe and China strong, but hopes are building that the situation will not deteriorate in Greece, said Peter Cardillo, chief market economist at Rockwell Global Capital in New York.

That's what the market wants, for fear to be contained and for things to proceed in an orderly fashion.

Banks continued a trend of rallying on signs of euro zone progress. U.S.-traded shares Deutsche Bank climbed 2.4 percent to $43.70 while Citigroup Inc rose 1.2 percent to $31.10 before the bell.

The FTSEurofirst 300 <.FTEU3> index of top European shares rose 1.4 percent while an index of European banks <.SX7P> advanced 2.5 percent. <.EU>

S&P 500 futures rose 8.8 points and were above fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average futures added 113 points, and Nasdaq 100 futures rose 13 points.

Amazon.com Inc slumped 9.1 percent to $176.74 in premarket trading a day after warning of a possible first-quarter loss and posting a steep drop in fourth-quarter profit.

Earnings continue to be a mixed bag. According to Thomson Reuters data, of the 204 companies in the S&P 500 that have reported results so far, 59.8 percent topped estimates, tracking below the beat rate at this stage of the earnings season in recent quarters.

Aetna Inc posted sharply higher quarterly profit in line with Wall Street's target early Wednesday.

Whirlpool Corp reported a drop in sales on weak global demand while Marathon Oil Corp swung to a fourth-quarter loss.

Facebook is expected to submit paperwork to regulators Wednesday morning for a $5 billion initial public offering and selected Morgan Stanley and four other bookrunners to handle the mega-IPO, sources said told Reuters unit IFR.

Economic indicators on tap include the January ADP employment report, due at 8:15 a.m. EST (1315 GMT). Economists see a gain of 185,000 private sector jobs, a steep fall from 325,000 in December, which included holiday hiring.

The ISM manufacturing report, also for January, will be released at 10 a.m. EST (1500 GMT), and is seen rising at 54.5 from 53.1 in December.

Wall Street closed its best month since October on a flat note on Tuesday, pressured by weaker-than-expected economic reports, including on consumer confidence and home prices, pressured sentiment.

(Reporting by Ryan Vlastelica; Editing by Jeffrey Benkoe)

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