As the largest stock market in the world, US have a large number of stock indices which are calculated in several ways for analyzing the stock market. The most common one are Dow Jones Industrial Average, the Nasdaq Composite and Standard & Poor's 500. It is known as the most reliable and widely acceptable indices.

The Dow Jones Industrial Average or DJIA is a price-weighted, the oldest and certainly the most popular stock-market indicator series. It is a price-weighted average of the 30 large, well-known industrial stocks that are generally the substantial companies (blue chips) and are listed on the NYSE. The constituent stocks are widely held by investors and well known for the quality and wide acceptance of their products and services, with strong histories of sustained growth.

The NASDAQ Index is a market weighted index of over 3700 stocks that are trade over-the-counter. Smaller capitalization companies dominate this index and has a market value that is only around 13% of the NYSE listed companies.

Standard & Poor's Corporation produce a number of capitalization-weighted indices for major US stocks (listed on various stock markets). The most widely-reported of these is a 500-stock composite index, known as the S&P 500 or S&P Composite. Since the S&P 500 is market cap weighted, larger weight stocks have a greater effect on the value of the index, whereas higher priced stocks have a greater effect on the level of DJIA. The S&P has become the main gauge for measuring the investment performance of institutional investment in the United States because of its broad industry coverage and the method of weighting used to create the index. Many institutional investors have created investment funds that are composed in the same manner as the S&P 500, called index funds. Institutional investors also use S&P 500 futures contracts (traded on Chicago Mercantile Exchange) to hedge their portfolio.