Value-Weighted Index: Explanation and How to Calculate
Value weighted indexes, also called cap-weighted indexes, may be used by investors to gauge the performance of various sectors of the stock market. Indexes effectively measure a specific portion or subset of the market, which can help investors get a sense of the market’s performance.
Some of the most commonly known and used value weighted indexes include the S&P 500, Nasdaq Composite, or Wilshire 5000. While these indexes can help investors get an idea of the market’s performance, they do have flaws, which investors would do well to keep in mind.
Key Points
• Value weighted indexes aggregate stock performance using market capitalization.
• These indexes serve as benchmarks for evaluating performance in financial markets.
• Calculation involves multiplying stock price by shares outstanding, normalized by a divisor.
• Other index types include price weighted and fundamentally weighted indexes, each distinct.
• Value weighted indexes reflect market trends but can be skewed by large companies.
Value Weighted Index Explained
Value weighted indexes are often used in the investment world as a stock market evaluation tool. A value weighted index is a tool used to aggregate the performance of multiple stocks into a cohesive whole represented by a single number. In other words, it’s a way to simplify a subset of the market’s performance, and make it relatively easy to get an idea of what’s happening in the market.
Value weighted indexes multiply current share prices by the number of shares outstanding to get the market cap for each component, or asset, of the index. These individual market caps are then totaled to get the overall value of the index.
When value weighted cap indexes began, the typical method of combining these values was by using a weighted average. For instance, if a stock’s market cap represented 10% of the overall market it would be weighted at 10%.
However, that method quickly becomes complicated as stocks are removed and added from the index, and some companies may be acquired or merged. Because of this, almost all indexes calculate a divisor to normalize the business decisions made at each company so that the index represents performance as accurately as possible without being affected by individual company decisions.
Let’s examine how different constituencies use the indexes for their particular needs, including traders, investors, and fund managers.
How Traders Use Indexes
Traders may differ from “investors” in that they’re characterized by short-term decision making. Traders use indexes as a benchmark to judge performance. They try to use indexes that match with their market moves.
For example, a technology focused investor might use the Nasdaq Composite to measure how well they are meeting their investment goals. They might also use the market index to determine when to enter or exit trades by gleaning any information they can about how the overall market is moving.
How Investors Use Indexes
Investors may differ from “traders” in that they have long-term horizons or investment goals, and thus, may be a bit more conservative in their investing approach. But similar to traders, investors also use indexes as a benchmark to compare how they’re doing in comparison. But investors may also be looking for less-risky investments with broad diversification.
Exchange-traded funds, or ETFs, may align with their goals, and ETFs often seek to replicate the various indexes by holding shares in proportions to match the index. Index investing can be a relatively simple way to start investing for beginners, as it allows for a degree of built-in diversification, tends to align with market performance, and typically comes with the benefit of low transaction fees.
But further research is always required to ensure that a specific ETF aligns with an investor’s strategy. With that in mind, it may be worthwhile to review available resources to help you learn more about investing in ETFs.
How Mutual Fund Managers Use Indexes
Mutual funds pool investment resources from a number of investors to try and provide diversification across sectors, and often pursue more conservative investments. Mutual fund managers may, again, use value weighted indexes as a north star, and try to match a market index’s performance, or beat it with the goal of generating returns for investors. However, keep in mind that investors can always lose money, too.
Mutual funds are also generally aligned with an index that parallels the investment philosophy of the fund, be that stocks, bonds, commodities, etc. So, there may be mutual funds that specialize or focus on investing in certain market segments, and use those as indexes to try and match.
How Hedge Funds Use Indexes
Hedge funds pool investment resources in a similar way to mutual funds, but typically follow a far more aggressive investment strategy and managers stick to an active investing style. Though they may be a bit more aggressive and less risk-averse, like other types of funds, hedge fund managers may use indexes as a benchmark to meet or beat in an attempt to generate returns for investors. Remember: There’s a potential for losses, too.
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Pros and Cons of Value Weighted Indexes
Value weighted indexes have their pros and cons, of course. Here’s a quick rundown of what the advantages and disadvantages of using value weighted indexes may be for investors.
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Pros:
• Tend to offer a comprehensive market perspective
• Are often comprised of less volatile, more mature companies
• Often include a broad-based, well-diversified list of companies and have low transaction costs
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Cons:
• The largest companies in the index may overwhelm performance
• May help generate market bubbles, with overpriced assets
• May encourage buying-high, selling-low investor behavior
How Market Value Weighted Index Is Calculated
Theoretically, the calculation of a value weighted index and the weights assigned to each component are easy to calculate. But as with most things, reality is a little more complicated.
To calculate a value weighted index, the first step is to multiply the price and shares outstanding (both of which are in near constant flux) of each component to get the market capitalization for each stock. For example, if you were trying to calculate a value weighted index comprising only three companies (which would not be indicative of a true index, but for simplicity’s sake, will work for an example), you’d first figure out the market capitalization of each company.
In this hypothetical example, here’s how that might look:
• Company 1: 50 shares outstanding at a current price of $10 = $500
• Company 2: 100 shares outstanding at a current price of $5 = $500
• Company 3: 75 shares outstanding at a current price of $15 = $1,125
Adding those up, the entire market value of this index is $2,125. To calculate the weights of each company in the index, you divide the value of the given company by the overall value of the index:
• Company 1: $500 ÷ $2,125 = weight of 23.5%
• Company 2: $500 ÷ $2,125 = weight of 23.5%
• Company 3: $1,125 ÷ $2,125 = weight of 53%
So, our total weight between the three companies is 100%, and Company 3 carries the highest weighting.
But remember: Due to complications with adding and removing companies from the index, dividends paid, buybacks, mergers, etc., there must be some normalizing done to the formula to remove large fluctuations caused by anything other than core performance.
This function is accomplished by the divisor, which oftentimes performs double duty by scaling the index values much smaller, say in the thousands rather than in the trillions, resulting in the following formula.
Index Value = ∑𝑖𝑝𝑖𝑞𝑖 / Divisor
Other Forms of Weighted Market Indexes
Value weighted indexes aren’t the only index-based securities measuring tool. Investors can utilize the following market index assessment options as well.
The Price Weighted Index
Price weighted indexes are another form of weighted market index, and a good example is the Dow Jones Industrial Average.
A price weighted index weights each component based on its stock price. Therefore a company trading at $200 will have a higher weighting than a stock trading at $5. This is despite the revenue, employment, or market capitalization of the respective companies.
The Fundamentally Weighted Index
A fundamentally weighted market index weighs companies based on some other financial criteria such as revenues, earnings, dividend rates, or other factors. Fundamentally weighted indexes allow tremendous flexibility in creating an index to match an investing criteria and strategy.
Unweighted Index
The term “unweighted” simply means that no weight is applied when measuring a stock against an index. Instead, the measurement gives equal weight to each index component. It is common to see unweighted versions of major indexes compared to the weighted indexes to get deeper market insights on, for example, how broad-based a market rally truly is.
The Takeaway
Value weighted indexes can be useful as performance benchmarks and to provide a quick overview of market conditions. By observing the index performance, investors may be better informed on entry and exit opportunities, as well as to measure their own investing performance.
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