The S&P 500 and DJIA are the two most-watched stock indexes in the U.S. However, these two benchmarks are very different: The Dow Jones Industrial Index tracks 30 large-cap stocks, the S&P 500 tracks the largest 500 stocks in the U.S. market The Dow Jones index is price-weighted; the S&P 500 is market-cap weighted The stocks in the Dow are chosen by a committee; the stocks in the S&P 500 are added according to a formula The Dow Jones uses a divisor; the S&P 500 is expressed vs. a base year