US stock futures retain rally mode after ADP

U.S. stock futures held sharp gains on Wednesday after data had private-sector job creation increasing in December.

The December ADP unemployment report comes ahead of the nonfarm payrolls on Friday.

Read MoreTrack US stock-index futures

On Wednesday afternoon, minutes from the Federal Reserve's mid-December meeting will be released, and could offer hints as to the timing of interest-rate hikes ahead.

"What would really help is some quantitative guidance on what we would need to see in either the labor market or inflation data to persuade the FOMC's core to alter its plan to begin raising rates in mid-2015. But we suspect that will be lacking from the minutes," said Capital Economics' Paul Ashworth in a research note on Tuesday.

Will the low oil price delay a Fed rate hike?
Will the low oil price delay a Fed rate hike?   

November's trade deficit could have narrowed on the back of collapsing oil prices, forecast Ashworth. Oil prices continued to fall on Wednesday, with the price of Brent crude temporarily dipping below $50 per barrel, for the first time since mid-2009.

Read MoreBrent dips below $50 for first time since May 2009

Agriculture company Monsanto will post results on Wednesday.

Other stocks worth watching include Boeing, after it reported on Wednesday that it delivered an industry record of 723 jetliners in 2014.

Read MoreBoeing deliveries hit record, Airbus wins on orders

Plus, Royal Dutch Shell has agreed to pay $83 million in compensation to 15,000 Nigerian fishermen affected by oil spills, in a settlement reported to be the biggest of its kind.

Outside the U.S., official data showed that falling energy prices pushed the euro zone into deflation, with prices falling 0.2 percent year-on-year in December.

And in Paris, at least 12 people were killed in a shooting at a French satirical news magazine Charlie Hebdo, which has published cartoons of the Muslim Prophet Muhammad, police told reporters Wednesday.

Read MoreAt least 11 dead after shooting at Paris magazine