Is One Better than Three?

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"I focus on the pie, I don’t care how they slice it.”  

 - Mark Vitner

There is this story about a man who goes to the local pizza shop for lunch and picks up a personal-sized pizza to go. The counter clerk asks the man: “Would you like your pizza cut into four pieces or six?” The man says: “Just cut it into four pieces. I don’t think I can eat six.”

David Loeper

This story calls to mind the noise we often hear about slicing our asset allocation pie into smaller and smaller pieces. A recent article in Financial Planning by Craig L. Israelsen entitled Multiply Returns by Dividing explored the premise that the return over the last 10 years would be higher if you just took Vanguard’s Total Domestic Equity ETF (VTI) and split it into its three market cap components of large cap, mid cap and small cap in equal weightings. I share what I believe was Israelsen’s intent – to improve clients’ lives – so I endeavored to evaluate his comparison more thoroughly and see if his premise achieved a benefit for clients.

Over the 10 years that Israelsen evaluated, small-cap and mid-cap stocks beat large-cap stocks by more than 5% annualized. VTI (the whole pie) owns those pieces too, but it weights them by market cap, which results in much smaller mid- and small-cap slices. Israelsen discovered that if you overweight the mid- and small-cap pieces by equally weighting them, you get a higher return, and minimal additional risk – at least for the 10-year period he wrote about.

Of course, it isn’t surprising that, if certain slices of the market pie outperformed others, then cutting larger slices of those outperforming pieces would improve the return. In fact, with perfect hindsight, you could have just put your whole pie into the small-cap slice, which outperformed large caps by nearly 6% over the 10-year period covered, according to the article.

After careful analysis, those extra slices might not be so filling after all. 

Ignoring additional risk

Israelsen minimized the risk posed by the additional 1.4% in annualized standard deviation that his equal-weighted (really over-weighted) slices introduce. It is helpful to analyze this probabilistically, on an apples-to-apples basis, to see the impact of this decision in every historical period available instead of the single window Israelsen considered, and to put it in the context of the longer time horizon of a typical client.

My company, Wealthcare, has a lot of historical data, which we use to build our capital market assumptions for our patented processes and systems. We also use that data to help us gain an accurate perspective of history. Instead of looking at one 10-year period and making a leap of faith that it was representative, I looked at 661 30-year periods starting in every month going back to 1926. Also, since it rarely makes sense for any client with specific goals to have an all-equity portfolio, I looked at balanced allocations that blended 7-10 Year Treasury bonds with either total domestic equities (like VTI), or an equal-weighted blend of small-, mid-, and large-cap stocks, as Israelsen did.