Market Index
An aggregate value produced by combining several stocks or other investment vehicles together and expressing their total value against a base value from a specific date. Market indexes are intended to represent an entire stock market and thus track the market's changes over time.
Investopedia Commentary
Index values are useful for investors to track changes in market values over long periods of time. For example, the widely used Standard and Poor's 500 Index is computed by combining 500 large-cap U.S. stocks together into one index value. Investors can track changes in the index's value over time and use it as a benchmark to compare their own portfolio returns to.
Related Links
Index Investing Tutorial
A Market By Any Other Name
See also: Benchmark, Composite Index, Index, Index Arbitrage, Index Fund, Portfolio, Standard and Poor's 500 Index - S&P 500, Weighted Average Market Capitalization