Futures Hold Gains After ADP Jobs Report

US stock index futures held their strong gains Wednesday, following news that private sector employment grew in line with estimates and after a handful of better-than-expected economic reports from Europe.

On the economic front, the pace of job creation by private employers slowed, adding 170,000 positions in January, but still met expectations, according to the ADP national Employment Report.

European shares were higher, after news that Germany's manufacturing sector grew in January.

Facebook is expected to file paperwork with regulators on for a $5 billion IPO, with Morgan Stanley the lead of its five underwriters. The company is currently looking at a valuation of $75 billion to $100 billion, which would be one of the largest initial public offerings in U.S. history.

Goldman Sachs, Bank of America Merrill Lynch, Barclays Capital and JPMorgan Chase round out the initial list of underwriters on the deal.

On Tuesday, the S&P 500 caught traders' attention when it triggered a "golden cross," meaning its 50-day moving average rose above its 200-day average. That is seen as the signal of an uptrend, but some analysts see it more as a psychological positive, confirming a move, rather than as a major signal.

Amazon.com plunged after the online retailer reported a sharp drop in revenue and also handed in a disappointing outlook. In addition, at least nine brokerages slashed their price targets on the firm.

Aetna gained after the health insurer posted a sharply higher profitin line with estimates as its members' low use of health services helped keep claim costs down.

Meanwhile, Northrop Grumman reported earnings that topped expectations, but revenue fell short of estimates.

Qualcomm and Electronic Arts are slated to post earnings after-the-bell tonight.

Also on the economic front, the ISM manufacturing survey is due at 10 a.m. and is expected to come in at 53.9, but some economists believe the number will be weaker. A measurement above 50 on the index, from the Institute for Supply Management, indicates an expansion of the U.S. manufacturing sector.

Auto sales, expected to at least match December 13.5 million annual selling rate, are expected to be reported throughout the day.

Weekly mortgage applications slipped last week, even as interest rates eased, according to the Mortgage Bankers Association.

In politics, Mitt Romney won the Florida elections for the Republican candidature to the presidency, beating Newt Gingrich.

—Follow JeeYeon Park on Twitter: twitter.com/JeeYeonParkCNBC

Coming Up This Week:

WEDNESDAY: ISM mfg index, construction spending, oil inventories, auto sales; Earnings from Qualcomm, Electronic Arts
THURSDAY: Jobless claims, productivity and costs, Fed's Fisher speaks, chain-store sales; Earnings from AstraZeneca, Deutsche Bank, Merck, Royal Dutch Shell, Sony, Unilever, beazer Homes
FRIDAY: Employment situation, factory orders, ISM non-mfg index; Earnings from Clorox

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