The yearly returns for the S&P cover all four financial quarters. An article in Investopedia.com states that the S&P 500 is considered by some as a more accurate barometer of the U.S. stock market because it includes 500 large-capitalization companies compared with the Dow Jones industrial Averages of 30 stocks.
The S&P also is more diverse than the DJIA because it contains stocks that are considered growth and value stocks. The top five current holdings in the S&P are: Apple, Inc., Exxon Mobile, Microsoft, Johnson & Johnson and Berkshire Hathaway. Wells Fargo, Proctor & Gamble, General Electric, JPMorgan Chase and Pfizer finish the top 10.