The S&P Composite 1500 Index, more commonly known as the S&P 1500, is a stock market index of US stocks published by S&P Dow Jones Indices. It combines stocks in the S&P 500, S&P MidCap 400, and S&P SmallCap 600. This index covers approximately 90% of the market capitalization of U.S. stocks and is a broad measure of the U.S. equity market.
The index was launched on May 18, 1995, with a first value date of December 30, 1994.Wikipedia