My $433 short in Ameritrade

I was so regret to short GOOG at $433 at the second/third trading day this year, after that short, GOOG jumped way up continuesly until $478 which almost kill my $433 short position. Luckily enough that I only use 20% margin, so I don't have to cut loss. I just leave this "regret short" in my "closet" for 2.5 weeks. It is really amazing GOOG even drop below $400 while GOOG started at $440.

GOOG dropped way down like a rock without any strong resistance.

I add "$420 cover buy at beginning", then when I found GOOG approcahe $422, I knew soem big thing will happen, and I cancelled the order. It dropped to $407 after lunch. then I add "$407.28 cover 50 shares order" to cover this position.

So my profit in Ameritrade for 50 shares of GOOG is
$433 * 50 - $407.28 * 50 - $10.99 - $10.99 = $1264.02 almost 8% of my fund.

It is so strang I even make 8% of money in an account with much less fund than my big account (IB).