Several indicators are already showing a start of a negative trend. The questions is how far will the DOW drop? The EMA 100, 200 & 500 have been providing support many times. In October however all of these levels were broken. My guess is that this time the DOW will go back to the EMA 500 level - if not any further.
I listed three possible scenarios A (EMA 50), B (trend line from 2011), C (EMA 500). Most likely will be a proper correction >10% from 18000 to 16000. Bottom will be set between January 26th and February 4th.