The NASDAQ-100 is a stock market index of 100 of the largest non-financial companies listed on the NASDAQ. It is a modified capitalization-weighted index. The companies’ weights in the index are based on their market capitalizations, with certain rules capping the influence of the largest components. It does not contain financial companies, and includes companies incorporated outside the United States. Both of those factors differentiate it from the Dow Jones Industrial Average, and the exclusion of financial companies distinguishes it from the S&P 500 Index.