When people think about deciding between investment advisors, or mutual funds, or even stocks, the temptation is to look at past performance. That’s the default. And it seems basic, you’re looking for returns, what else would you look at? What else could you even look at?

The problem is the past performance we see is short term. You’ll see three to five year histories on your account statements, Morningstar defaults at a ten year history (if the fund has been around that long), and the news rarely talks about anything further back than the last year. Those are relatively short periods of time, especially when we’re talking about market returns. Instead of comparing past performance in advisors and mutual funds over the past ten years, we should be looking at long-term historical returns of asset classes.

An asset class is a group of similar securities that tend to move together. The main general asset classes are equities (stocks), fixed income (bonds), and cash. Each of these, but especially the equities group, can be broken down further. In equities, we see large vs small, value vs growth, U.S. vs international. For an example, a very popular asset class is U.S. Large Growth, which is basically the S&P 500. We have returns data on these asset classes all the way back to the early 20th century. That information can tell us much more than the past ten years. We can see which asset classes tend to outperform others, we can see how the different asset classes correlate to each other, and we can know what returns and risk a fund or portfolio can expect over long periods of time. A ten-year history of returns is almost irrelevant. Over ten years any asset class could outperform any other, but we don’t know when or which. So to look backward at the performance of a fund is not only unhelpful, it’s more often hurtful. A good ten-year history on a fund, or even an asset class, deceives us into thinking the performance will continue in the future. The short-term history the only information we know to use, and besides that, it seems to make sense. But that’s the opposite of a good investing strategy. Instead, let’s analyze the asset class data going back as far as it goes, understand where returns come from, and diversify our portfolio’s in a way that’s consistent with the data. Then we let the market perform and deliver results. Our balanced diversified portfolio won’t always be the big winner year by year, but over the long haul, it will outperform anyone trying to predict market movements based on ten-year histories, or any other material information.