Stock Market Charts
INDEXUnderstanding the Major US Stock Indices
A stock index tracks the combined performance of a group of companies as a single number. The S&P 500 measures about 500 of the largest US companies and is weighted by market capitalization, making it the most widely used benchmark for the US market. The NASDAQ Composite includes thousands of stocks listed on the Nasdaq exchange and is heavily weighted toward technology and growth companies. The Dow Jones Industrial Average tracks just 30 large, established "blue-chip" companies and is price-weighted, so higher-priced stocks move it more than larger ones.
Frequently Asked Questions
What is a stock market index?
It is a single figure that represents the combined value of a defined basket of stocks, used to gauge how a market or segment is performing over time.
What is the difference between the S&P 500 and the Dow?
The S&P 500 holds about 500 companies weighted by market value; the Dow holds 30 blue-chip companies and is price-weighted, so it is narrower and moves differently.
When are US stock markets open?
Regular trading runs 9:30 a.m. to 4:00 p.m. Eastern Time on weekdays, excluding US market holidays.