Bid/ask prices aren't "set" prior to the market opening. They represent the best bid and the best asked and can be quite wide, particularly in illiquid stocks. Since most people pull their bids at the close, the spread in the morning can be very wide. All you have to do to see this is log on at that time. Your fill has nothing to do with the broker that you use. Your sell stop loss price was lower than the AM bid so it was hit.
many responses with valid points, in additions, you can put "trigger only in regular trading hour flag" with your stop if your broker has this option. market makers/specialists often create artificial bid/ask in premarket to hunt stops with illiquid stocks. It just like taking candy from a baby/ pick up nickle from street to them.
Thanks again everyone! I figure that's what happened... market maker placed a bid pre-open that was ridiculously low and triggered stops, even though nothing ever traded at that price. Like taking candy from a baby (me) My online broker doesn't have many options for changing default triggers, etc. so I am going to shop around a bit more I guess. H
you have not..as i said before-MM,exchange or whatever placing the bid cannot trigger anything. he did not steal the candy from you..your broker did..i would personally check,where the trade was executed..pretty sure that your broker was on other side and transaction never reach the exchange. i would file a complain about it and change the broker asap.
http://money.howstuffworks.com/nasdaq-opening-closing-cross1.htm http://money.howstuffworks.com/nasdaq1.htm http://www.nasdaqtrader.com/content/ProductsServices/Trading/Crosses/fact_sheet.pdf