Shares of Virgin Mobile USA fell 54 per cent on Thursday after the mobile network operator reported disappointing subscriber gains and cut its 2008 earnings forecast by 40 per cent.

The stock, which was sold for $15 a share in an initial public offering in October, fell $1.90 to $2.30 on Thursday after several analysts cut their ratings on the stock citing growing concerns about the impact of increasing competition and weakness in the US economy.