U.S. stock-index futures pointed to a flat open on Wednesday, with investors keeping one eye on Ukraine and another on the day's ADP employment report – widely viewed as an indicator for the monthly non-farm payrolls number.
(Read more: US and Russia setfor talks on Ukraine tension)
ADP found the private sector added 139,000 jobs in February.
(Read more: Employment data ison the way, but will it matter?)
In addition, the non-manufacturing ISM index will be published at 10 a.m., and the employment subcomponent may also provide some clues as to the direction of payrolls.
At 2 p.m., the Federal Reserve will release the March edition of its Beige Book its region-by-region assessment of the economy.
Former Fed Chairman Ben Bernanke is due to speak at a leadership conference in Johannesburg, South Africa on Wednesday, and the Dallas Fed's Stanley Fisher will speak in Mexico City.
Shares in Europe and Asia traded cautiously on Wednesday, despite the threat of imminent conflict in Ukraine receding. Russian President Vladimir Putin appeared to back away from military action in the Ukrainian region of Crimea on Tuesday and U.S. Secretary of State John Kerry condemned Russia's aggression in a news conference in Kiev.
(Track: European shares live)
—By CNBC's Katy Barnato