What is the S&P 500?

When you hear someone say that ‘the market is up’ or ‘the market is down,’ often, people are talking about how the S&P 500 is doing. But what exactly is the S&P 500?

With thousands of companies listed publicly in the stock market in the US alone, investors, finance professionals, economists, and policymakers need ways to assess overall trends and measure performance. This is where the S&P 500 comes into the picture as an index that can demonstrate overall market movements. 

In this article, we’ll cover:

• Why the S&P 500 is important
• S&P 500 companies and how it’s calculated
• How it differs from other indexes
• What does it mean to invest in the index?

Why is the S&P 500 important? 

While numerous indexes can measure market performance, the S&P 500 is the most popular, alongside the Dow Jones Industrial Average (or DJIA). And it’s not just popular; it’s really good at showing you what’s going on.

The S&P 500 achieves this accuracy by encompassing the 500 largest companies listed on the New York Stock Exchange (NYSE) or the Nasdaq exchange, ranked by their respective market capitalizations. The remarkable aspect here is that these 500 companies collectively contribute to roughly 80% of the total market capitalization of all publicly traded companies. This means that when you consider the S&P 500, you are essentially gaining insights into the performance of a substantial majority of the stock market.

This level of representation is crucial because it allows investors, analysts, and policymakers to gauge the health and direction of the market more accurately. By following such a significant portion of the market’s total value, the S&P 500 becomes a barometer of overall market trends. It effectively captures shifts in various sectors, industries, and economic conditions. 

This is really helpful for people who want to invest their money or just understand what’s happening in the economy. When you hear that ‘the market is up’ or ‘the market is down,’ often, people are talking about how the S&P 500 is doing.

And because the S&P 500 is so important, many investment funds (both mutual funds and ETFs) are based on it. These index funds let you invest your money in a way that follows how the S&P 500 is doing. You essentially get a piece of each company without having to buy individual shares of each one.

Companies of the S&P 500 in 2023

Because it is such a prominent index, many people ask: is the S&P 500 inclusive of all US stocks? The answer is no. However, it includes most of the overall market cap through the stocks it measures. 

Since the S&P 500 includes the 500 largest market cap companies, you may wonder how and when this list gets updated or if companies are on it for life once they make it. Because companies go up and down in market cap value, they make their way on and off the list. Similarly, as companies overtake one another in size, they represent a larger portion of the index, as it is weighted proportionally, making it known as a “free float-adjusted market-cap-weighted index.” 

As a result, the largest companies can have a distinct impact on the performance of the index since they are more represented than their peer stocks. This is part of what makes the S&P 500 such an accurate representation of the economy and market as a whole. 

Here are the top 10 companies in the S&P 500 by index weight as of November 2023: 

1. Microsoft
2. Apple
3. Amazon
4. NVIDIA Corporation
5. Alphabet (class A)
6. Meta Platforms Inc (class A)
7. Alphabet (class C)
8. Berkshire Hathaway Inc. (class B)
9. Tesla
10. Unitedhealth Group Incorporated

The S&P 500  vs other stock indexes

The S&P 500 is not the only stock market index. There are many ways to measure market performance and aggregate stock data. Let’s explore how the S&P compares to another popular index. 

When it comes to calculating the S&P 500, remember that:

• It includes the largest 500 companies measured by market capitalization. 
• Companies are weighted differently within the index according to their market cap. 
• It is a free float index.
• These factors result in the S&P representing around 80% of the total market cap in the stock market. 

Dow Jones Industrial Average (DJIA)

While S&P 500 represents the 500 largest companies and offers a broader view of the market’s health, the Dow Jones Industrial Average (DJIA) includes only 30 blue-chip companies and calculates its average based on stock prices, not market value, making it less comprehensive but more sensitive to high-priced stocks. The list of companies can also change over time according to adjustments in the economy and market. 

Nasdaq Composite Index

While the S&P 500 covers the broader market, the Nasdaq Composite focuses exclusively on companies listed on the Nasdaq exchange, emphasizing technology-heavy firms, making it a narrower representation with a focus on tech-driven sectors. The Nasdaq Composite is a market-value-weighted index, where the impact of each component is proportionate to its total market value, rather than just its market capitalization. This can lead to differences in how individual companies affect the index’s movements.

Beyond these two examples, there are also the Nikkei 225, DAX, Nasdaq Composite, Russell 2000, and many more. 

Investing in the S&P 500

Since it isn’t a company itself, you can’t invest directly into the S&P 500 like it was a stock, but you can buy shares in index funds that track the S&P 500’s performance as a whole. It’s like getting a piece of all the companies in the index, which spreads out your investment and gives you diversity like the index itself.

Investing in index funds can be helpful in many ways:

• Diversification for your portfolio: Since the index represents 500 companies, you won’t expose yourself to extensive risk by hinging on a single business’s performance. 
• Exposure to market gains: You will have the opportunity to profit from overall market upward trends and build wealth with your investment. 
• Passive investment strategy for beginners: You won’t continuously trade or manage money. When you invest in an index fund, it’s simple to put the money in and let it sit for the long term, especially when you’re new to investing. 
• Low cost: You won’t be actively trading, and index funds are not managed actively like some other more costly funds, so the associated fees will be low. 

Investing in the S&P 500 offers a strategic approach to benefit from the collective performance of 500 leading companies and purchasing shares in index funds that mirror the index’s performance allows you to tap into its diversified potential.

Investing made easy.

Start today with any dollar amount.

Get Started