TXF file for your tax software. Cobra Trading. Getting your data out of Cobra is fairly simple. Login to your account and follow the steps below: 1 Company, Margin Rate*. Lightspeed logo, 7.50%. Etrade, 9.25%. Tradeking (Ally ), 8.50%. TD Ameritrade, 9.75%. * Rates for the firms listed above are based on 1 Aug 2012 TradeKing and Zecco, two innovators in the online brokerage industry, announced today the merger of the two firms has officially closed.