Update

We saw "huge bar" yesterday... There is two options with huge bars - exhaustion, final blow off so to speak and the second new move up/down has just begun. Looking at this chart it looks to me like exhaustion bar. We have a move with three waves(corrective), which corrected to MA50 on the daily chart - one down(finished with such bar too) two up and three down. I will bet on exhaustion bar and finished pull back.
SP500 found support yesterday at the second target 1820. Long trade with stop bellow 1820 is not a bad idea.
If I am wrong a move lower has just begun... you should see the SP500 moving lower, without loosing too much time(than sell it with stop above the high for the bounce before the close), moving and closing bellow MA50 on the daily chart.