Perform said full-year revenue would be about 6 percent below its previous expectations, with year-on-year growth now expected to be in excess of 35 percent. It said its German and U.S. markets were performing particularly badly.

The majority of the revenue shortfall would fall through to core earnings, it said on Thursday.

Shares in the British group, which listed at 260 pence in April 2011, plunged 49 percent to 219p at 1256 GMT.

Perform buys online rights to major sports events and supplies video clips or live content to groups including newspaper publishers and bookmakers.

Analysts were expecting the group to report full-year revenue of 215 million pounds ($351.9 million) and core earnings of 51.1 million pounds, according to a consensus of seven brokers compiled by Thomson Reuters.

Joint Chief Executive Oliver Slipper said he was "disappointed" with the performance of the business in the fourth quarter which would also impact on the group's outlook for 2014.

($1 = 0.6110 British pounds)

(Reporting by Paul Sandle; editing by Keiron Henderson and Elaine Hardcastle)