As you can see there is a lot of confluence at 3970 level (This chart become quite busy with the trendlines)
If we do gap down tomorrow below 3970, I will be looking to buy 3928-39SPX level for a broken trendline test, if not more.
This chart is similar to the ES, but has a higher level of support, so they have a bit different short term look one from another to my eyes, but the main picture is the same.
I really dont have much of a support if 3890-3910.50 is gone till 3744SPX!
So it better hold that level and ideally the 3928-39SPX support box.
Same as the ES, SPX has its trading cycles bearish now, expect short the rips all the way till the 19th of Dec!
Have a good night