Index funds have been making the news lately but for the wrong reasons. Some commentators speculate that the rise of “indexing” as an investment approach might be casting too wide a net and is harmful to markets. The idea is that index investors “blindly” buy the performance of markets without paying attention to underlying fundamentals. This can lead investors to overpay for poorly performing companies that happen to be in the index and also to drive up prices for the “big” stocks like Apple, Amazon and Microsoft.
While this makes sense in theory, rest assured that we’re not blindly doing anything and that markets are healthy, even with the rise of indexing. This is confirmed in the following essay from Dimensional Funds. I’ve pared down the original to get to the core ideas. The language is a bit wonky but it’s worth a quick read. If you have any questions about how we use index funds and ETFs in your portfolio, please don’t hesitate to ask. Now on to the article…
Over the last several years, index funds have received increased attention from investors and the financial media.
Some have even made claims that the increased usage of index funds may be distorting market prices. For many, this argument hinges on the premise that indexing reduces the efficacy of price discovery. If index funds are becoming increasingly popular and investors are “blindly” buying an index’s underlying holdings, sufficient price discovery may not be happening in the market. But should the rise of index funds be a cause of concern for investors?
Using data and reasoning, we can examine this assertion and help investors understand that markets continue to work, and investors can still rely on market prices despite the increased prevalence of indexing.
While the popularity of indexing has been increasing over time, index fund investors still make up a relatively small percentage of overall investors. For example, data from the Investment Company Institute shows that as of December 2017, 35% of total net assets in US mutual funds and ETFs were held by index funds, compared to 15% in December of 2007. Nevertheless, the majority of total fund assets (65%) were still managed by active mutual funds in 2017. As a percentage of total market value, index-based mutual funds and ETFs also remain relatively small, with domestic funds comprising only 13% of total US stock market capitalization in 2017.
In this context, it should also be noted that many investors use nominally passive vehicles, such as ETFs, to engage in traditionally active trading. For example, while both a value index ETF and growth index ETF may be classified as index investments, investors may actively trade between these funds based on short-term expectations, needs, circumstances, or for other reasons. In fact, several index ETFs regularly rank among the most actively traded securities in the market.
Trade volume data are another place to look for evidence of well-functioning markets. Despite the increased prevalence of index funds, annual equity market trading volumes have remained at similar levels over the past 10 years. This indicates that markets continue to facilitate price discovery at a large scale.
Even though the historical empirical evidence suggests that the rise of indexing is unlikely to distort market prices, let’s consider the counterargument that the rise of indexing does distort markets and in turn causes prices to become less reliable. In this scenario, wouldn’t one expect stock-picking managers attempting to capture mispricing to have an increased rate of success over time?
In a world where index funds bias prices, we should expect to see evidence of such an impact across an index fund’s holdings. In other words, there should be more uniformity in the returns for securities within the same index as inflows drive prices up uniformly (and outflows drive prices down). Taking the S&P 500 Index as an example, however, we see that this has not been the case. The S&P 500 is a widely tracked index with over $9.9 trillion USD indexed or benchmarked to the index and with indexed assets comprising approximately $3.4 trillion USD of this total.
In 2008, a year of large net outflows and an index return of –37.0%, the constituent returns ranged from 39% to –97%. In 2017, a year of large net inflows and a positive index return of 21.8%, the constituent returns ranged from 133.7% to –50.3%. We would also expect that constituents with similar weighting in traditional market cap-weighted indices would have similar returns. In 2017, Amazon and General Electric returned 56.0% and –42.9%, respectively, despite each accounting for approximately 1.5% of the S&P 500 Index.
Despite the increased popularity of index-based approaches, the data continue to support the idea that markets are working. Annual trading volume continues to be in line with prior years, indicating that market participant transactions are still driving price discovery. The majority of active mutual fund managers continue to underperform, suggesting that the rise of indexing has not made it easier to outguess market prices. Prices and returns of individual holdings within indices are not moving in lockstep with asset flows into index funds.
Lastly, while naysayers will likely continue to point to indexing as a hidden danger in the market, it is important that investors keep in mind that index funds are still a small percentage of the diverse array of investor types. Investors can take comfort in knowing that markets are still functioning; willing buyers and sellers continue to meet and agree upon prices at which they desire to transact.
Have questions? Ask me. I can help.
- Created on .