John Bogle ran his regular “Ask Jack” column, he addressed a reader question about portfolio rebalancing and mentioned that he didn’t engage in the practice himself, and offered this data to readers:
Hi, Mr. M,
Sorry it’s taken me so long to respond to your thoughtful note. Busy!
We’ve just done a study for the NYTimes on rebalancing, so the subject is fresh in my mind. Fact: a 48%S&P 500, 16% small cap, 16% international, and 20% bond index, over the past 20 years, earned a 9.49% annual return without rebalancing and a 9.71% return if rebalanced annually. That’s worth describing as “noise,” and suggests that formulaic rebalancing with precision is not necessary.
We also did an earlier study of all 25-year periods beginning in 1826 (!), using a 50/50 US stock/bond portfolio, and found that annual rebalancing won in 52% of the 179 periods. Also, it seems to me, noise. Interestingly, failing to rebalance never cost more than about 50 basis points, but when that failure added return, the gains were often in the 200-300 basis point range; i.e., doing nothing has lost small but it has won big. (I’m asking my good right arm, Kevin, to send the detailed data to you.)
My personal conclusion. Rebalancing is a personal choice, not a choice that statistics can validate. There’s certainly nothing the matter with doing it (although I don’t do it myself), but also no reason to slavishly worry about small changes in the equity ratio. Maybe, for example, if your 50% equity position grew to, say, 55% or 60%.
In candor, I should add that I see no circumstance under which rebalancing through an adviser charging 1% could possibly add value.
Use your own judgment, but perhaps these comments will help.
Best,
Jack
Over my 40 word limit but interesting...tb
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