S&P 500

Definition

A stock market index that tracks about 500 leading U.S. companies. Companies with larger market values generally have a greater effect on the index.

Investors use the index as a benchmark for large U.S. stocks. It is weighted by the market value of shares available to investors, so the largest constituents typically have more influence on its daily movements. Many investment funds aim to track its performance.

Example

The S&P 500 rises from 5,000 to 5,050 in a day. The index gained 1%, even though some of its stocks may have fallen.