Reader Mailbag: How is the stock market index of any significance for individuals?

This week, we have a reader question from Jasmin:

How is the stock market index of any significance for individuals?

The significance of a stock market index (or any other index for that matter) is that it is a benchmark. In other words, investors can use indices as a yardstick to measure and/or compare slices of their portfolio to.

For most investors, indices can be used to evaluate the performance of the individual asset classes in their portfolio. Investors can compare the risk and return metrics of an allocation to those of an appropriate index. When utilizing an actively managed strategy, an appropriate index or index fund can be viewed as the opportunity cost of using the active strategy.

If you own US large-cap stocks, you might compare the volatility and performance of those stocks to the S&P 500. If you own international stocks, you might compare them to the MSCI EAFE. You can compare the bond portion of your portfolio to the Barclays Agg or a number of other indices. There are multiple indices for various sectors, regions, countries, and so on. In fact, today there are more indices than stocks!

Although the above is relatively straightforward, many investors misuse indices. Below are two of the more common errors that I see:

  • Comparing a multi-asset class portfolio to a single asset class index. I meet many people who compare their portfolio of global stocks and fixed-income to the S&P 500. The S&P 500 could probably be used to benchmark the US large-cap equity portion of the portfolio, but certainly not the entire portfolio.
  • Viewing an index as a goal. Each individual investor has unique goals and their portfolio should reflect this. Even the largest indices have some fairly substantial risks, which investors should be aware of and may want to avoid. For instance, the “China Region” (China, Hong Kong, and Taiwan) makes up 40+% of most broad-based emerging markets equity indices or the Barclays Agg is overwhelmingly government bonds, which offer much more duration than yield today. These are just two examples of where investor goals may be inconsistent with an index’s composition. Note: Money managers may benchmark to a single index, but this is because they typically run single asset class strategies and are concerned with relative performance, neither of which is typically true of individual investors.

So, the short answer is that individuals can use indices to evaluate single asset class strategies/managers and should not be used for much more than that.

Full Disclosure: Nothing on this site should ever be considered to be advice, research or an invitation to buy or sell any securities, please see my Disclosures & Disclaimers page for a full disclaimer.