I read an interesting post on another US forum recently in which...

I read an interesting post on another US forum recently in which the poster provided many examples of bubbles over the last 40 years with the signal being the % above a 300EMA as follows:
Sugar 1974 (160%) - falls 87% over 2 years;
Gold 1980 (150%) - falls 69% over the following years and remained depressed for decades;
Nasdaq 2000 (69%) - falls 84% over 3 years;
AMZN 2000 (180%) - falls 95% over 2 years;
QCom 2000 (323%) - falls 88% over 3 years;
Canola Oil 2008 (67%) - falls 53% over the following years;
Crude Oil 2008 (50%) -falls 70% in 9 months;
Silver 2011 (85%) - falls 72% over the following years and is depressed today.

Now Bitcoin (2017) is the highest off them all at (500%), so it's certainly appears to be the mother of all shorts.