VXX is trading slightly below the suggested stop parameter of 26.90 in pre-market trading due to the fact the futures are indicating a slightly higher open.  Many traders, myself included, will often wait until the first 30 minutes or so of trading to let the opening imbalances in the market settle before establish new positions or closing existing positions.  Obviously, this is not a luxury afforded to many part-time traders who work and not able to use manual stops but those who entered a VXX long yesterday might want to wait until shortly after the open before entering (or cancel & then re-enter) the stop.