Companies reporting quarterly results before Wall Street opens included Dow component Merck, which posted quarterly sales slightly below expectations, hurt by competition from cheaper generic drugs. It forecast full-year earnings at the low end of Wall Street estimates.Its shares were up nearly 3 percent in early New York trading.
Disney and Twitter will report after Wall Street closes.
Federal Reserve speakers on Wednesday include Charles Plosser, a hawkish, voting member of the FOMC (Federal Open Market Committee), and Dennis Lockhart. Also, Fed Governor Daniel Tarullo will testify on the Volker Rule before the House Financial Services Committee.
After an exceptionally weak start to February, Wall Street closed higher on Tuesday helped by some encouraging earnings and a steadier tone in emerging market currencies.
The uptick in the U.S. helped boost European and Asian shares early on Wednesday.
(Track: European shares with CNBC)
—By CNBC's Katy Barnato