Sorry, that’s my fault - I was being lazy.
The convention in the asset management industry is to quote the proportion of a portfolio held in equities first. So, 30:70 means 30% in equities, 70% in bonds, etc.
Now, you can argue about what exactly I mean by “equities” (do I include small caps, emerging market equities, etc?) or bonds (global or euro-denominated only, short, intermediate or long duration?). But frankly that is very much of second level importance to the equity/bond split decision.
So, when I said there was no reason to expect a portfolio that “glides” from 30:70 to 90:10 to outperform a fixed 60:40 portfolio, on average, what I mean is a portfolio that starts with a 30% allocation to equities and ends with a 90% to equities will, on average, have a 60% allocation to equities.
Hopefully that makes sense.
But it’s late so please come back to me if it doesn’t and I’ll have another go tomorrow.