I'm done for the day here, having caught the reversal trade at 1202. By the way for those who give a damn about it. Reversal days are not that hard to anticipate (especially for the S&P market). Put up a chart using 15 or 30 min bars and scan left. This is a market that cycles back and forth. Look for previous wide range bars and you will start to see the patterns appear.
Actually it is not "that simple". If you use the search function, you will notice that there are some valuable articles on this subject posted in the past.
In addition to actual transactions, bids and cancelled bids, offers and cancelled offers also signify "pressure". Some sharp professionals have developed profitable systems by analyzing how bids/offers and cancellations affect price movement. Here in this office, we have a person trading a system that uses the ratio of bids/offers to actual transactions. Sorry I can't say more about it.
Good luck in your search.
Lefty.