Say one has 2 to 1 overnite buying power. I get a margin call and have to sell some shares to meet it. Now I have 900 shares left (QLD) at fridays close of 32.95 bid wich totals $29655. Shoulndnt my equity be half of this or $14827.50. Penson is the clearinghouse and Speed trader is the broker. It shows my equity is 11,406. What am I missing?