Definition
A single number that tracks the prices of a group of stocks or other assets, to show how that slice of the market is doing.
The story
Instead of checking 500 stock prices, you check one: the S&P 500. Some indexes weight bigger companies more (the S&P 500, the Nasdaq-100), while the Dow weights stocks by price. You can't buy an index directly, but you can buy funds and futures that track one.
Why markets watch it
Indexes are how "the market" is measured in almost every headline.
Connects to
We explain why it moves markets. What you do with it is your call. Commentary and education only. Not financial advice. All terms