(FILES) This file photo taken in Washington, DC, on May 1, 2014 shows bitcoin medals.
Bitcoin makes its debut on a major exchange on December 10, 2017, a milestone for the digital currency that has some investors excited but others nervous. The Cboe Futures Exchange in Chicago will open trading in bitcoin futures at 2300 GMT on Sunday, a move that is expected to be followed a week later by a rival listing on Chicago Mercantile Exchange. / AFP PHOTO / Karen BLEIER
