Here is a 30 minute bar chart of the e-mini day sessions for the past two weeks. The question I am thinking about now is just how big will the drop from Friday's 872 high turn out to be?
The first thing to consider is whether or not a supply shock has hit the market. Looking at today's first hour volume and comparing it to the first hour volume of previous days (red lines) shows that today's first hour did not see unusually high trading volume to the downside. So this tells me to expect a reaction which is comparable in size to the ones we have seen on the way up from the 666 low on March 6.
The most recent one was 30 points, but the market has already gone past that mark. The other two reactions on the way up measured 46 and 55 points. I note that a 46 point drop from 872 would take the market down to 826 (purple rectangle). This is just above midpoint support based on the reaction which started on April 6 at 848 and carried the e-minis down to 803 (purple dotted line).
So the coincidence of these two levels makes me think that the 825 level is a pretty good guess for the low of the current reaction. The only thing that would force me to reevaluate the situation would be an obvious, high volume supply shock - something that is not yet visible in the market's activity.