Kevin Green says Monday's session was one of the "top 5" most compressed trading days for the SPX. The index kept to a tight range that once again tested 6,440 as support but still had no chance to test 6,500 resistance. Part of that reasoning comes from light volume on the session. Kevin adds that volatility remains "relatively low" but notes that it typically ticks up this week on a historic basis. Looking ahead to the week, he sees Jackson Hole serving as the biggest market mover.