Standard & Poor's 400 Stock Index

Standard & Poor's MidCap 400 Index

A stock index that tracks 400 publicly-traded companies with a medium amount of market capitalization. While not as well-known as the S&P 500 index, the S&P Midcap 400 is considered a leading index on mid-cap companies. Mid-cap SPDRs are depository receipts that track the S&P Midcap 400.

Standard & Poor's 400 Stock Index (S&P 400)

A broad-based index of 400 industrial stock prices weighted on the basis of market value (stock price multiplied by shares outstanding). It includes listed and over-the-counter stock but is heavily influenced by the stock of large corporations. The index is based on a value of 10 during the period 1941-43.