The S&P 500 Index is a free-float capitalization-weighted index, which includes 500 large-cap common stocks traded actively in the United States.
The S&P 500 index, also known as S&P 500, SP500 or Standard & Poor's 500 index, includes 500 large-cap common public stocks actively traded in the U.S. stock exchanges. After the Dow Jones Industrial Average, the S&P 500 index is the most widely followed index of large-cap U.S. stocks, capturing 75% coverage of U.S. equities. It is considered a bellwether for the American economy, as it is includes both growth stocks and the generally less volatile value stocks.
Calculation Of Index
The S&P 500 index has traditionally been market-value weighted, meaning, movements in the prices of stocks with higher market capitalizations have a greater effect on the index than companies with smaller market caps. Since 2005 the S&P 500 index is float weighted. That is, Standard & Poor's now calculates the market caps relevant to the index using only the number of "float" shares, which are available for public trading.
Selection Of Index Components
The S&P 500 index is focused on U.S.-based publicly traded companies, although there are a few legacy companies with headquarters in other countries. The stocks included in the S&P 500 are those of large publicly held companies that trade on either of the two largest American stock market companies; the NYSE Euronext and the NASDAQ OMX. The components of the S&P 500 index are selected by committee, so they are representative of the industries in the United States economy.
Index Historical Chart
The S&P 500 index in its present is published since 03-04-1957. S&P 500 index reached all-time highs just before the last financial crisis on 09-11-2007, when index reached intraday level of 1,576.09 points. The latest minimal value of the index was reached in March 2009, when index fell below the 680 level.
Index Sector Allocation
The S&P 500 index has the following sector allocation (as of 5/28/2010):
Information Technology: 18.81%
Health Care: 11.63%
Consumer Staples: 11.22%
Consumer Discretionary: 10.69%
Telecommunication Services: 2.84%
The S&P 500 index components shown in table below are sorted by weightings and valid as of 5/28/2010.