LONDON (Reuters) - Shorting shares in GameStop, the video game retailer at the centre of the ongoing retail trading frenzy, cost hedge funds a total $12.5 billion over January, data from financial analytics firm Ortex showed on Monday. The losses were inflicted by small-time investors who piled into GameStop, pushing up the shares and forcing many hedge funds to buy them back to cover losses. GameStop shares are up 1600% year-to-date. Ortex data showed $5.9 billion worth of GameStop shares were out on loan as of Friday or 49% of the total freefloat. In Europe, short-sellers booked $28 million loss on their bets against Cineworld. Almost 24% of its freefloat is on loan.