Quote from Maverick74:
That's a very good question. I actually pulled up my data from 2011 to take a look. That was the last year we really had any kind of meaningful downside volatility. The answer is, we got number line confirmations to the UPSIDE right before major corrections.
Now why and how this happen? Well, the corrections we got in April and July of that year both came right off swing highs. So the market was acting well going into the highs. My theory to this is that sharp corrections are outliers. ACD is not effective in predicting outliers because by definition, outliers fall outside your data set. ACD does a good job modeling "normal" markets. It takes the patterns in volatility, the centering of important time zones and together with observed price action behavior, spits out very predictable results.
Market crashes or corrections happen when something breaks or snaps. It's very hard to time those events. The goal is simply to have a risk management protocol in place in order to deal with them rather then try to predict them. Now, if you looked under the hood at other things going on in the market, perhaps there would have been some clues. I've said before many times that often the best tells are in the currencies. When you see money sharply moving out of risk countries and into safe havens, something is up. If there is a tell out there when a crash or sharp correction is coming, you are much better off looking at the currency charts then the SP 500.
I've got a pretty good eye so I tend to notice very subtle things going on. I'm sure you will notice some action in a particular stock or sector that seems off or out of character that will clue you in to something happening. But it's highly unlikely that the number lines will be the tell.
For example in 2007, credit spreads were blowing out while the spoos were making new highs. And by credit spreads I mean things like the TED spread and the OIS. Watch these like a hawk. When they start to blow out, you'll be amazed how few people even notice. Both these spreads telegraphed the 2007 top and the sharp 2011 correction we had after the debt downgrade.