Quote from Pekelo:
There is actually an opposite of ADU, that I call SDD. SDD stands for Step Down Day, and it is the pattern how a certain type of selloff day advances. The name comes because the chart looks like a step, a big drop first, consolidation next and another big drop into the close.
SDD is pretty much the mirror image of an ADU. The timeline goes like this:
1. Dow drops a decent -100 or more by 11 am. (Lately there tend to be a midday bottom around 11:40)
2. For the next 3 hours there is a sideway consolidation, when the Dow is bouncing between the BBs.
3. Further drop after 2 pm.
Timing it I use the already mentioned BBs and W %R. If you have new lows after 2 pm, just stay short until at least 3:30...