Here is an idea I want you to test. Let us call an event that depicts the change in both inside Bid and inside Ask levels. Let us call this event a âunique price changeâ. Let us assume that those changes are the result from a âRandom Walkâ type of a process. It is a well-known fact that the binderies for such a random walk (its mean deviation) could be calculated as squareroot(2N/pi) where N is number of unique steps (in our case it is the number of unique price changes described above). If one can draw those binderies on the chart in real time it seems that every time that the close price of a bar (it does not matter what the bar length is, I tested it briefly on 5 min bars) ends up outside of those binderies it has a strong tendency to reverse it self. I have briefly tested the idea on ES contract. I also included in this post a code for eSignal (it seems to me that many people on ET still use it). I would like you to test the idea in real time and discuss it. May be we will find the way to improve it and use it efficiently for the intraday trading. Looking forward to your responses. P.S. to test the idea on other securities you need to change the tick value from 0.25 to the tick value of the security you are trying to test. Also, the lines will not appear on the history bars because bid/ask numbers could only be retrieved in real time. Play with it.