The Standard & Poor's 500 also known as SPX 500 is a capitalization-weighed index of the top 500 American stocks. It consists of 500 large companies most of which are considered as blue-chip companies in the United States. SPX 500 is widely viewed as a leading indicator of the performance of the large cap US equities. As a result, the SPX 500 is one of the most monitored equity indexes and passes as an excellent representation of the U.S. stock market. The index captures an estimated 80% coverage of available market capitalization thus is regarded as a more representative market index as it's comprised of 500 companies as compared to the Dow Jones Industrial Average's 30. It is popular among investors globally for offering some of the best investable and benchmark indices. The S&P 500 list is checked and reviewed quarterly to ensure that the index's eligibility criteria are met.