What is the S&P 500?

The S&P 500 is a broad-based stock market index, consisting of the 500 largest US public companies. The diversity and size of the companies it tracks make the S&P a proxy for the entire stock market. You can't invest in the S&P 500 itself, but you can buy an index fund that duplicates its stocks and performance.

Is the S&P 500 a float-weighted index?

The S&P is a float-weighted index, meaning the market capitalizations of the companies in the index are adjusted by the number of shares available for public trading. Because of its depth and diversity, the S&P 500 is widely considered one of the best gauges of large U.S. stocks, and even the entire equities market.

Can you invest in the S&P 500?

You can't directly invest in the S&P 500 — it's just a list, not a stock itself. But a variety of publicly traded mutual funds and ETFs (exchange-traded funds) buy securities that track the S&P 500, or a particular group of the companies within it, like high-dividend-paying companies or more growth-oriented companies.

Is the S&P 500 a Russell Index?

The S&P 500 is a member of a set of indexes created by Standard & Poor's. The Standard & Poor's set of indexes is like the Russell index family in that both are market-cap-weighted indexes unless stated otherwise (as in the case of equal-weighted indexes, for example).