As you can read from news headlines whole market is went to correction and this was quite predictable.
If you pay attention to 1W chart, RSI was on 92 overbought level, which is a strong signal to fix profits and play bearish game. But I don't think that's it's another financial crisis, U.S. is not dumb and it surely learned a lot of lessons since 2008. Although, market needed correction and it happened.
I put support lines on 1W chart to see from which levels price can bounce for short term trades, but for longer term I guess 21,600 is good level to stop going down, but it may go down lower until 3/1 Fan line.
Be careful with trades and don't forget about stop-losses.