5 Potential Warnings About Index Funds

Investing in index mutual funds and ETFs gets a lot of positive press, and rightly so. Index funds, at their best, offer a low-cost way for investors to track popular stock and bond market indexes. In many cases, index funds outperform the majority of actively managed mutual funds.

One might think investing in index products is a no-brainer, a slam-dunk. However, to nobody’s surprise, the providers of mutual funds and exchange traded funds (ETFs) have created a slew of new index products in response to the popularity of index investing. Here are five things to know about index funds as you plan your investment strategy.

Key Takeaways

  • Index funds have become a major force among investors who seek passive index strategies as opposed to active management.
  • Indexing has several benefits including lower costs, broad-based diversification, and lower taxes.
  • Investors, however, must consider the index fund that they select since not every one is low-cost, not some may be better at tracking an index than others.
  • Moreover, owning an index does not mean you are immune from risk or losses if the markets take a downturn.

5 Reasons To Avoid Index Funds

Not All Index Funds Are Cheap

People who work for large corporations often have the opportunity to invest in low-cost index funds offered in 401(k) plans that offer institutional shares of certain funds. If your 401(k) plan contains index funds from providers such as Vanguard Group or Fidelity Investments, you can be pretty confident that these are low-cost. Both funds from these families offer share classes with even lower expense ratios and also offer a full range of index funds across various stock and bond asset classes.

Unfortunately, 401(k) plans do not always offer index funds this cheap. This may be true if your plan provider is an insurance company or brokerage firm offering its own proprietary funds. While the advice to focus on index funds in your 401(k) plan is often sound, make sure that you look at the index funds offered in your plan to ensure that you are making the best choices. For 401(k) participants fortunate enough to have a selection of several low-cost index funds, the advantage over higher-cost active funds can be significant.

All Indexes Are Not Created Equal

There is a wide range of low-cost index mutual funds and ETFs covering widely used indexes across the nine domestic Morningstar style boxes, as well as widely used foreign stock indexes. The same holds true on the fixed income side of things.

The proliferation of ETF index products in recent years has led to a whole slew of index funds with underlying indexes that were essentially created in the “lab” with results that are largely back-tested as opposed to having real market results.

While back-testing is a valid analytical tool, investors need to be careful about ETFs using indexes that consist of a large amount of back-tested historical results. There are few to no known rules governing the underlying assumptions used in applying this data and the simulated results may not be an accurate portrayal of the risks of ETF.

Index Funds Don't Necessarily Reduce the Risk of Loss

Investors in an index fund or ETF tracking the S&P 500 during a bear market in stocks will experience losses just like the index. In a broad-based selloff like the 2008-09 financial crisis, investors in other index products tracking real estate in the form of a real estate investment trust (REIT) or emerging market stocks could suffer large losses as well.

Index fund investors do, however, eliminate manager risk. This is the risk of an active manager underperforming the benchmark associated with their investment style due to the investment choices they make in managing the fund.

An index fund provider may occasionally change the way it tracks the index, or shift to a new benchmark entirely. This can be done to reduce costs or to make the fund more efficient. While not usually impacting most buy-and-hold investors, one should stay on top of their index funds' holdings for changes like this, as mutual fund providers continue to compete on price.

Index Funds Don't Ensure Investment Success

Just investing in an index fund or two doesn't mean that you're on your way towards achieving your investment or financial planning goals. Index funds are tools just like any other investment product. In order to gain the most benefit from using index funds either exclusively or in combination with active funds, you need to have a strategy.

Index funds work quite well as part of an asset allocation plan. Index funds (at least the ones tracking basic core benchmarks) offer purity within their investment styles. Many financial advisers put together portfolios of index funds that are allocated in line with their client’s risk tolerance and their financial plan. Others may use a “core and explore” approach where index funds make up much of the portfolio (the core) with selected active funds to hopefully enhance returns (the explore portion).

The Bottom Line

Investing in index mutual funds and ETFs can be an excellent low-cost strategy for all or a part of your investment portfolio. Like any other investment strategy, investing in index funds requires that you understand what you are investing in. Not all index products are the same and investors need to look beyond the “index fund” label to ensure they are truly investing in a low-cost product that tracks a benchmark that fits with their investing strategy.

Article Sources
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  1. Crane, Alan D., and Kevin Crotty. "Passive versus active fund performance: do index funds have skill?." Journal of Financial and Quantitative Analysis Vo. 53, No. 1. 2018. Pp. 33-64.

  2. S&P Dow Jones Indices. "SPIVA U.S. Mid-Year 2021."

  3. Morningstar. "Fact Sheet: The New Morningstar Style Box Methodology," Pages 1-2.

  4. Barron's. "Watch Out, ETFs. Here Comes Custom Indexing."

  5. Financial Times "More than 10% of ETFs have made changes to their index, data show."

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