The S&P 500 and How It Works

How the S&P 500 Tells You About America's Health

NYSE outside
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The S&P 500 is a stock market index that tracks the stocks of 500 large-cap U.S. companies. It represents the stock market's performance by reporting the risks and returns of the biggest companies. Investors use it as the benchmark of the overall market, to which all other investments are compared. Over the last 10 years, it has returned 9.49 percent per year. In 2017, it returned 21.83 percent. S&P stands for Standard and Poor, the names of the two founding financial companies that merged.

How It Works

The S&P 500 tracks the market capitalization of the companies in its index. Market cap is the total value of all shares of stock a company has issued. It's calculated by multiplying the number of shares issued by the stock price. A company that has a market cap of $100 billion receives 10 times the representation as a company whose market cap is $10 billion. The total market cap of the S&P 500 is $23.5 trillion. It captures 80 percent of the market cap of the stock market. 

The index is weighted by a . It only measures the shares available to the public. It does not count those held by control groups, other companies, or government agencies.

A  each of the index's 500 corporations based on their liquidity, size, and industry.  It rebalances the index quarterly, in March, June, September, and December. To qualify for the index, a company must be located in the United States and have a market cap of at least $6.1 billion.

 At least 50 percent of the corporation's stock must be available to the public. Its stock price must be at least $1 per share. It must file a 10-K annual report. At least 50 percent of its fixed assets and revenues must be in the United States. Finally, it must have at least four consecutive quarters of positive earnings.

 

The S&P 500 includes real estate investment trusts and . The stock must be listed on the New York Stock Exchange, Investors Exchange, NASDAQ, or BATS. It cannot be over-the-counter or listed on pink sheets.

In 2017, the in the S&P 500 (with a weighted market cap) were Apple, Microsoft, Amazon, Berkshire Hathaway B, Facebook, JP Morgan Chase, Johnson & Johnson, Exxon Mobil,  Alphabet C (formerly Google), and Alphabet A. 

The makeup of the S&P 500 industries reflects that of the economy. In 2017, the  was

  • Information Technology: 24.9 percent
  • Financials: 14.7 percent
  • Health Care: 13.7 percent
  • Consumer Discretionary: 12.7 percent
  • Industrials: 10.2 percent
  • Consumer Staples: 7.7 percent
  • Energy: 5.7 percent
  • Utilities: 2.9 percent
  • Materials: 2.9 percent
  • Real Estate: 2.8 percent
  • Telecom Services: 1.9 percent 

How the S&P 500 Is Different from Other Stock Market Indices

The S&P 500 has more large-cap stocks than the Dow Jones Industrial Average. The Dow tracks the share price of 30 companies that best represent their industries. Its market capitalization accounts for almost one-quarter of the U.S. stock market. The Dow is the most quoted market indicator in the world.

The S&P 500 has fewer technology-related stocks than the NASDAQ. The NASDAQ also includes the stocks of companies that are privately-owned. 

Despite these differences, all these stock indices tend to move together. If you focus on one, you will understand how well the stock market is doing. In other words, you don't have to follow all three.

Milestones

DateCloseEvent
January 3, 1950      16.66Record closing low. 1st close.
June 4, 1968    100.381st time above 100
October 19, 1987    224.84Black Monday largest % loss (20.5%)
March 24, 1995    500.971st close above 500
February 2, 1998 1,001.271st close above 1,000
October 9, 2007 1,565.15Highest close before financial crisis
October 13, 2008 1,003.35Largest % gain of 11.6%.
March 28, 2013 1,569.19New record high
August 26, 2014 2,000.021st close above 2,000
January 26, 2018 2,872.87Record closing high

History and Ownership

The by Standard & Poor. McGraw-Hill acquired it in 1966. The S&P Dow Jones Indices owns it now. That is a joint venture between McGraw Hill Financial, CME Group, and News Corp, the owner of Dow Jones. The S&P Dow Jones Indices publishes over 1 million indices. 

How to Use the S&P 500 to Make Money

Although you can't invest in the S&P, you can mimic its performance with an  S&P Index fund. You could also buy shares of stocks that are in the S&P 500. Be sure to weight them in your portfolio according to the market cap, as the S&P does.

You should use the S&P 500 as a leading economic indicator of how well the U.S. economy is doing. If investors are confident in the economy, they will buy stocks. Some experts believe the stock market can predict what the savviest investors think the economy will do in about six months.

Besides following the S&P 500, you should also follow the bond market. When stock prices go up, bond prices go down. There are many different types of bonds. They include Treasury bondscorporate bonds, and municipal bonds. Bonds provide some of the liquidity that keeps the U.S. economy lubricated. Their most important effect is on mortgage interest rates. To help you follow the bond market, Standard & Poor's also rates bonds.

Since the S&P 500 only measures U.S. stocks, you should also monitor foreign markets. That includes emerging markets like China and India. It's also good to keep 10 percent of your investments in commodities, like gold. They tend to hold value longer when stock prices drop.