Here is a five minute bar chart of e-mini day session trading. Today's range estimate is the blue rectangle. The market rallied from its open at 872.50 all the way to 880.25. This was just a shade above the midpoint of yesterday's day session range which coincided with yesterday's close (purple dotted line) - both useful resistance levels.
Then sellers entered the market (red arrows), putting in a wide range down bar on heavy volume. This looks like a decisive rejection of the 880 level and makes me believe that today's day session high has been established. I now think the market will drop to or perhaps a little below its recent low at 865.25. In my view this action is all part of a base building process which I think will be completed next week. The next big move should be upward into the 965-980 range.