Do Indices Have a Weight Problem?

Comparing Market-Cap and Equal-Weight Indices

Investors have long been comparing market-cap and equal-weight indices. But what are the major differences, really? 

A look at one of the most prominent market indexes illustrates the distinction.

The S&P 500 is a market cap-weighted index designed to represent the overall performance of the U.S. stock market by tracking the performance of the 500 largest companies in the country. A market cap-weighted index means that the larger a company’s market cap, the more influence it has over the movement of the index. Larger companies account for a big portion of the index’s performance. 

But the foremost index also has a lesser-known version: S&P 500 Equal Weight Index. This equal-weighted index uses the same 500 companies, but assigns each company the same weight, regardless of size. In other words, smaller companies have as much influence over the index’s performance as larger ones. 

These two types of indices tend to perform differently, depending on market conditions. An equal-weighted index might favor the performance of small caps during bull markets, while exposing investors to increased volatility. On the flip side, it may see sharper losses during bear markets than a market cap-weighted index. 

As a rule of thumb, market cap typically offers increased stability, while equal weight offers the potential for increased returns with a greater risk of loss.

The Rule and the Exception

When analysts talk about the S&P 500, they are most likely talking about the market cap-weighted version. This version may be the most widely used benchmark in the stock market — the performance of individual equities and funds are routinely compared against its returns. 

The S&P 500 became the industry standard because it is perceived as providing a more accurate representation of the overall market and economy. Larger companies tend to have more influence over broad economic trends, which allows the weighted index to give a clearer picture of overall economic health. 

There are also some drawbacks to the equal-weighted version. Smaller companies tend to be more volatile, increasing the index’s volatility. Additionally, the index requires constant rebalancing to maintain its equal weight, which can result in increased transaction costs.

The Investment Implications

For investors weighing the pros and cons of market cap versus equal weight, the decision largely hinges on the same factors as other investment decisions: individual goals, investment strategy, and risk tolerance. 

The market cap-weighted index is considered the more conservative, passive option, offering broad market exposure with lower volatility. Established companies tend to experience fewer ups and downs during periods of economic downturn, and so does the market cap-weighted index. Consequently, the traditional S&P 500 tends to be well-suited to investors prioritizing long-term growth over short-term gains potential. 

On the flip side, the equal-weighted index is considered a more aggressive approach. Its risk profile is higher, but it also provides the potential for outperformance, specifically from smaller companies that may benefit more from bull markets and other economic climates beneficial to small-cap companies. This version of the index also provides a measure of increased diversification.

Related Reading: Diversify Your Portfolio to Meet Your Financial Needs

In the end, it’s up to investors to decide what type of index fits their goals. Interested in exploring exposure to a certain index? Reach out to Griffin Asset Management today.

Sources:

Investopedia: Market Weight vs Equal Weight S&P 500 ETFs

Raymond James: Market Capitalization vs Equal Weighted