As our friends at SpotGamma note, for those looking at market support (and resistance), the main levels remain similar to that of Wednesday: support at 4600 and resistance at that 4650 area which is also the gamma flip point. The bulk of positive gamma is positioned up into the 4675-4700 which is where we see major resistance. As gamma is negative we anticipate large directional swings in todays shortened session. More key support details in the video below.
But perhaps more important than chartism today is what the VIX will do. With the fear index currently around 27, the VIX complex is in sharp backwardation (shown below).
This is generally what we see when markets are crashing, however SpotGamma does not (yet) consider this a full-blown S&P500 crash because, as they noted earlier this week, gamma is quite low, "and along with holiday liquidity it was likely markets were poised for a lot of volatile chop."