Today’s action is nicely representative of the power of the FastTrack (free) indicator:
You may easily notice that the price touches the first resistance at 3850, breaks to the high and then the second resistance at 3872 becomes support. All very technical, the difference I that the levels are calculated the day before and you know in advance.
Just give it a try, FastTrack is free at free.spxbot
The FastTrack indicator is an a.i. indicator developed and tested for years, that indicates the bearish/neutral/bullish levels of the daily action for the next day.