Commodity money as a theoretical backing for federally issued "gold certificates" to substitute for the gold. Between 1933 and 1970 (when the U.S. officially left the gold standard), one U.S. dollar was technically worth exactly 1/35 of a troy ounce (889 mg) of gold. However, actual trade in gold bullion as a precious metal within the United States was banned after 1933, with the explicit purpose of preventing the "hoarding" of private gold during an economic depression period in which maximal circulation of money was desired by influential economists. This was a fairly typical transition from commodity to representative to fiat money,
Commodity price index the index. The first such index was the CRB ("Commodity Research Bureau") Index, which began in 1958. Due to its construction it was not useful as an investment index. The first practically investable commodity futures index was the Goldman Sachs Commodity Index, created in 1991 and known as the "GSCI". The next was the Dow Jones AIG Commodity Index. It differed from the GSCI primarily in the weights allocated to each commodity. The DJ AIG had mechanisms to periodically limit the weight of any one commodity and to remove commodities whose weights became too small. After AIG's financial problems in