Prices have indeed begun to collapse as suggested if the SPX was in an ending diagonal triangle. If this was an ending diagonal - which indicates overall exhaustion of the 2 year uptrend - then even more price collapse should come quickly. But for now major support held for today.
If prices can hold above around 1838 SPX, and then somehow manage to creep up again to another new all-time high, it could be indicative of yet a bigger ending diagonal triangle (as suggested by the upper green line.)
Either way things are getting interesting. Note the higher volume bar of today's downdraft. Technically speaking that is bearish.