What is Equal-Weight Index? (Plain English Definition)
Definition: An equal-weight index gives every stock in the index the same percentage weight, regardless of market capitalization.
Equal-Weight Index Explained Simply
An equal-weight index assigns identical weightings to every stock it holds. In an equal-weight S&P 500 ETF, each of the 500 companies gets a 0.2% weight, whether it is a $3 trillion giant like Apple or a $15 billion smaller company. This contrasts with the traditional capitalization-weighted approach where larger companies dominate.
Equal weighting has several effects on portfolio characteristics. It gives significantly more exposure to smaller companies and less to the mega-caps. This means an equal-weight ETF behaves more like a mid-cap fund than a large-cap fund. It also requires regular rebalancing to maintain equal weights as stock prices change, which means more trading and potentially higher expenses.
Historically, equal-weight indices have sometimes outperformed their cap-weighted counterparts over long periods, partly because of the greater small-cap exposure and the rebalancing effect (systematically selling winners and buying laggards). However, they have underperformed during periods when a few large companies drive most of the market's gains, as happened with large tech stocks in recent years.
Equal-Weight Index Example
In a cap-weighted S&P 500 ETF, the top 10 stocks might represent 33% of the fund. In the equal-weight version (RSP), those same 10 stocks represent only 2% (10 times 0.2%). If those top 10 stocks surge 30% while the rest rise 5%, the cap-weighted fund gains about 13% while the equal-weight fund gains only about 5.5%. But if the top 10 fall 20% while the rest rise 10%, the cap-weighted fund gains only about 3.4% while the equal-weight fund gains about 9.4%.
Why Equal-Weight Index Matters for ETF Investors
Equal-weight ETFs offer ETF investors an alternative approach to market indexing that reduces concentration risk. If you are concerned that a cap-weighted index is too dependent on a handful of giant companies, an equal-weight version provides more balanced exposure. For ETF investors, the choice between cap-weighted and equal-weight comes down to your views on concentration and company size. Cap-weighted is simpler, cheaper, and more tax-efficient. Equal-weight provides broader exposure but costs more and may underperform when large-cap stocks are leading the market. Understanding both options helps you make an informed decision about how to structure your core stock holdings.
Equal-Weight Index vs Capitalization-Weighted Index
| Equal-Weight Index | Capitalization-Weighted Index |
|---|---|
| An equal-weight index gives every stock in the index the same percentage weight, regardless of market capitalization. | See full definition of Capitalization-Weighted Index |
While equal-weight index and capitalization-weighted index are related concepts, they serve different purposes in the world of ETF investing. Understanding both terms helps you make more informed decisions about which funds to include in your portfolio and how to evaluate their performance.
Read our full explanation of Capitalization-Weighted Index →
Related Terms
Deepen your understanding of ETF investing by exploring these related concepts:
Capitalization-Weighted Index
A capitalization-weighted index assigns more weight to companies with larger market values, so bigger companies have more influence on the index's performance.
Market Capitalization
Market capitalization is the total value of a company's outstanding shares, calculated by multiplying the stock price by the number of shares.
Index Fund
An index fund is a type of investment fund designed to match the performance of a specific market index, such as the S&P 500.
Portfolio Rebalancing
Portfolio rebalancing is the process of realigning the weightings of assets in your portfolio back to your original target allocation.
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