September is the weakest month of the year historically on SPX, and started yesterday with a significant show of weakness, with SPX gapping below the daily middle band and closing below it. This is the third close below the daily middle band in the last few weeks and, as with the other two, we may see a rejection back up into another marginal higher high, but these are significant signs that SPX may be topping out for at least a larger retracement here.
SPX daily chart:

