But good diversification is only one layer of protection and as investors have learned, it can have an inherent weakness in bear markets
where correlation between asset classes can go to one at light speed.
Correlations between all asset classes could also be high, reducing diversification benefits.
That's because the standard deviation of returns changes over time, as does
the correlation between asset classes.
This has become harder over the years as
the correlation between asset classes has increased in what has become a risk - on, risk - off world, reducing some of the benefits of diversification.
It's interesting to look at
the correlation between these asset classes.
Correlations between asset classes may be surprisingly high when leverage rapidly unwinds.