For a long time I have noticed that naively filling every asset class (or every second, third, or fourth asset class) often gave better results than most "expert" portfolios using both
https://portfoliocharts.com/ and
https://www.portfoliovisualizer.com/. Here is my formal investigation into it.
Rules: I equally weighted every or every 2nd, 3rd, or 4th asset class using both withdrawal types (safe and perpetual) at
https://portfoliocharts.com/portfolio/portfolio-matrix/. Spare change went to cash, or was taken away from cash, to keep all other assets equally weighted. This was a form of sandbagging my hypothesis, because Cash is Trash as Portfolio Charts confirms.
Note 1: I like to use withdrawal rates best of all backtesting objectives. Are long term returns more important, or is stability more important? With safe withdrawal rate there is no bullshitting about one or the other is more important: if it was more important why didn't it result in a higher safe withdrawal rate?
Note 2: There are really only let's generously say 3 data points affecting the results here. All of the portfolios except Japan had their worst case in 1970-1974. Some of the countries give slightly different results so lets call that a second effective datapoint, as we can throw cold water on some of the weakest contenders. Pay special attention to Japan, as that is the only true out of sample datapoint for most "expert" portfolios.
Note 3: Portfolio Charts has 9:10:4:3 HomeStocks:ForeignStocks:Bonds:"Real"Assets, so all naive portfolios follow that basic ratio, which might be significant. I did on odd occasions throw out TSM and International TSM for simplicity.
Note 4: SWR is determined based on the single worst year in the record for 30-year rolling returns. Average returns would make a very different ranking.
Here are the results. Naive portfolios are white, "experts" get colors. The withdrawal rate is listed for each, could be some typos but the rankings should be correct. I am surprised to note that even with cash sandbagging, the "experts" mostly demonstrated no skill and underperformed naive asset class selection. Only a few expert portfolios appear to show skill, including the Ivy, 7Twelve, and Pinwheel. Even the 7Twelve and Pinwheel portfolios seem to be more about extreme diversification than skill, with 12 and 8 slices. Perhaps a future data point will show that the Ivy Portfolio was just lucky? The average "expert" portfolio looks to have underperformed the average naive portfolio.
And here is what went into the naive portfolios. TMI I know.
If I ever make my own portfolio I will call it the "I'm an Idiot Portfolio" :D
Thanks mjr! Had to run just as I posted, not sure what went wrong.