The S&P 500: Biased and Misleading

You’ve seen headlines like these:

“S&P 500 crashes today”

” The S&P 500 rose as earnings optimism rises”

“Record year for stocks, as S&P 500 up double-digits”

…and so on.

The problem with these statements is that they’re using the S&P 500 as a proxy for the overall market. I’ll be the first to admit that no index completely represents the market at all times. But in this article, I’ll point out some of the issues with the S&P 500.

The S&P 500 index is a market-capitalization weighted index made up of 500 of the largest publicly-traded companies in the United States. The stocks within the index represent a significant portion of value of all companies in America.

I am a big fan of low cost index investing. So why am I shit-talking the S&P 500?

Three reasons:

First, the index is arguably actively managed. All indices have a pre-programmed set of rules to determine its constituents, weightings and rebalancing frequency. An index and its characteristics need to be defined – like everything else in life – and that definition is the creation of a human being (or team of humans) making some sort of decisions. The activity undertaken to create these rules (and the activity in executing these rules) means that indices (like the S&P 500 index) may not be as passive as investors believe. While an investor can make a passive allocation to an index, that investor must first understand and believe in how that index is constructed.

Second, the index is highly concentrated. The chart at the beginning of this articles shows that the largest 5 stocks of the S&P 500 accounts for the same market cap as the last 279 companies of the index. These five companies are Microsoft, Amazon, Apple, Alphabet and Facebook. While these companies may seem like behemoths that could survive anything – thus deserving their big weights in the index – one only has to go back as far as 2010 to see a completely different composition. In 2010, the largest five stocks in the S&P 500 included Exxon, GE and Berkshire Hathaway. Where are they now? This degree of concentration presents a risk to investors, as the success of index constituents waxes and wanes. Essentially, the performance of the S&P 500 is dependent on the success or failure of just 5 companies.

Third, the index is effectively a buy-high sell-low strategy. Put simply, to get added to the index a company needs to be meaningfully large. Companies aren’t born large, so by the time they are big enough to be added to the S&P 500 they have often experienced years of growth. In other words, companies are added to the index AFTER they have performed well and potentially already trading at elevated levels. In contrast, a company is removed from the index if it falls from grace and has shrunk considerably (or even gone bankrupt) due to years of weak performance. Ideally, investments should be bought BEFORE they perform well and sold BEFORE they start to underperform. The S&P 500 (and many other indices) does the opposite, and is effectively a buy-high sell-low strategy.

Takeaway: If you are looking for simple, diversified access to passive exposure to equities I would first look for indices that are well constructed. These well constructed indices may not be what you see in the newspaper headlines, and some are proprietary to mutual fund or ETF manufacturers. Look for investment products that provide ‘total market’ exposure while capping the weight of each underlying holding. Take a look at the top 10 holdings of whatever index ETF or fund you are researching to ensure they represent no more than 25% of the overall assets. Finally, also consider an index ETF or fund that includes small, mid and large cap stocks to provide exposure to all phases of company growth (i.e. not simply to companies that have already gotten big).

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