Yesterday VXX reversed Short at the Close, by 9 cents. Today, it is running. The Buy-stop on the 240 minute trade chart is $35.89. Below is the Hourly (60 minute) trading chart. If VXX is going on an extended run, it will first exceed and stay above its 60 minute reversal level of $34.12. The system can't buy VXX Dec $35 calls until $35.89. But, if you want a closer execution and are willing to take the risk, the 60 minute chart provides that earlier, albeit riskier entry.