Well, The free portion of Ivy Portfolio portfolio wasn't very long, but it suggested people should read asset allocation first.
In asset allocation, it has the period 2000-2009 (which is really selectively picking a bad patch for shares).
It has, over that period, bond 6.33%, stocks -0.95%, REITS 10.63%, and then shows
that having 1/3 of each of these has a 6.13% return.
I'm really starting to become convinced that this diversity can improve returns is a mirage. It seems like its just saying, ok, if shares give X, and there's some other class that gives Y (and Y>X), then a blended combination of Y and X is better than X.
If that's all this argument is, then dahhh.. either just buy the higher earning class if its expected to be bigger, or if its just a weird anomaly, just ignore it - in my mind, the hopes that diversity can improve CAGR, is lapsing back to just smoke and mirrors.