U.S. stock index futures were indicating a mildly higher start for stocks as investors started the countdown to Thursday's U.K. referendum on EU membership and awaited further testimony from Federal Reserve Chair Janet Yellen.
Yellen will appear before politicians for a second day Wednesday, testifying in front of the House Committee on Financial Services from 10 a.m. ET.
That's after the Fed chair testified to a Senate panel Tuesday, where she warned that a Brexit could usher in an era of uncertainty and suggested that an interest rate hike may wait for a boost in hiring numbers.
Ahead of existing home sales data due later in the morning, the FHFA House Price Index rose 0.2 percent on a seasonally adjusted bases in April from the previous month, while March's figure was upwardly revised to a 0.8 percent increase.
Investors are now counting down the hours to Britain's referendum, with polls set to open Thursday morning.
The International Monetary Fund is also set to hold a press conference on the state of the U.S. economy following their consultation mission, at 9:30 a.m. ET.
Major company earnings today include Red Hat, which is expected to release earnings results after the bell at approximately 4:05 p.m. ET, followed by Bed Bath & Beyond at 4:15 p.m. ET.