Just got off the phone with Ameritrade, as I was disputing a stop market order on my FB.
Turns out a new law came into effect today, although Ameritrade never alerted anyone about it. If you place a stop market or stop limit order, it will no longer be triggered by the bid & ask prices as it has always been. Now they are going by the "last" price. This is more pertinent to things like UGAZ/DGAZ, or other stocks/ETFs that have a spread between the bid & ask that is wide, ie., greater than a penny. Also something like VIXX, where the last can be completely different than the bid & ask. The last price can be 5 or 10 cents higher/lower than the bid/ask, but you will still be stopped out. No amount of complaining would sway Ameritrade, but they gave me 5 free trades. Whoopy! Just be aware of the rule change, which for some reason wasn't publicized, or maybe i just missed it.