When talking about passive investing and diversifying across many asset classes, a common quip is that if you knew in advance which asset class would perform best, you’d just put your money there. Since you can’t, you diversify.
Well, in a recent issue of MoneySense, Norm Rothery delved into the “hot potato” that does exactly that (he also wrote about it in August of 2015). Using a momentum strategy, it goes all-in on whatever the hottest sector was over the previous 12 months. The extra return over a more vanilla, diversified approach is sweet — too much to ignore without some further thought.
Norm puts in a number of disclaimers at the end of the article, but before going ahead it’s worth thinking about those risks and more.
Firstly, I have to point out that going all-in on something (even something as diversified as a broad-market ETF) opens you up to blow-up risk. It didn’t happen in the recent past, but that’s not saying it couldn’t. That’s a fundamental risk of concentration — you could go all-in on the one asset class that goes down one year, then switch and catch the next loser.
It also looks to me like a strategy that’s possibly not very robust and vulnerable to execution risk. I don’t have data on returns with monthly resolution going back very far to test out how robust it may be, but it’s easy to get for the ETFs available to Canadian investors for the 2008 market crash and do a spot check. Norm mentions that the monthly rebalanced version of the hot potato only fell 10% in 2008 and recovered by 2009. Going into 2008 the hot potato had you do a few little dances between XIC and XBB. In August of 2008 it would have had you buy XIC, just to eat a 12.5% loss, and switch back to XBB the next month. If you went on vacation and missed that switch by two months, you were down 33%; if you missed by five months you were down 40%.
Momentum is a weird thing in the markets: it’s there, it looks to be exploitable, but it doesn’t have a “mechanistic” basis: controlling costs does, as does diversification — you can predict that those “should” work in the long term. But for momentum, even if there is some psychology or whatever to the momentum effect in general that makes it a real effect that may possibly form the basis of a successful strategy, what is it about trailing 12-month returns and monthly rebalancing that worked so very well for the historical check of the hot potato? Could that shift in the future to 6 or 24-month returns being the momentum sweet spot, and leaving someone using 12-month/rebalanced monthly strategies in the lurch? Are the features of momentum stable and exploitable enough to bet it all (or even compromise with dynamic sector weightings) on something like the hot potato? Or is this an accident of over-fitting historical data? Those question marks may make it a difficult strategy to stick to when a period of underperformance eventually comes along.
Larry Swedroe has an article looking at momentum in general that’s worth reading, in particular the line about how the strategy becomes less valuable as correlations between global markets increase.
I don’t know, and haven’t invested a tonne of time doing research here — hopefully Norm or someone else has a more data-driven answer. For now, I’m not brave enough to try it with actual dollars in the uncertain future — I’ll stay diversified and lazy.