US Stock Market indices - Economist

The Dow Jones Industrial Average is officially known as the "Dow Jones Industrial Average" and is among the most widely recognized indexes, and is used to measure the performance of the American stock market.

It was established in 1896 when the index was tracking 12 industrial companies, then the index expanded in 1929 to include 30 companies, considered one of the largest and most influential companies.

Officially launched in March 1957, the S&P 500 Index of 500 companies is a market capitalization-weighted index meaning that companies with a large market capitalization are more important than small companies.

Although the index includes only a select group, many analysts and traders consider it a benchmark for the market.

The Nasdaq Composite Index was launched on February 5, 1971, and includes more than 5,000 companies, as well as many types of stocks such as real estate investment trusts.

Like the S&P 500, the Nasdaq Composite is a market value-weighted index, but it fluctuates more broadly.

The Nasdaq 100 is a subset of the Nasdaq Composite Index, an index that includes the 100 largest companies, based on market capitalization and the most actively traded.

It now includes 108 companies, and this index was launched in January 1985 and later became one of the most tracked indices in the world.