The S&P GSCI serves as a benchmark for investment in the commodity markets and as a measure of commodity performance over time. It is a tradable index that is readily available to market participants of the Chicago Mercantile Exchange. The index was originally developed in 1991, by Goldman Sachs. In 2007, ownership transferred to Standard & Poor's, who currently own and publish it. Futures of the S&P GSCI use a multiple of 250. The index contains a much higher exposure to energy than other commodity price indices such as the Bloomberg Commodity Index. Wikipedia