I trade alot premarket and there really is no set market as everything is limit orders and you put your own prices in..Went to short a stock the other day and got filled before 9.30...Bought to cover 2 minutes later for a nice profit...Got called about half hour later and was told trade was busted..Not only that, but I now owned the stock which was never my intention...Stock kept going down so not only did I not make money, I lost alot...Anything to do or anyone know any firm that would cancel my buy or put it in their error acoount to protect their customers? Any ideas?