United States Copper Index Fund (CPER) The United States Copper Index Fund (NYSEARCA: CPER ) is an exchange-traded security that looks to track the price movements of the Summer Haven Copper Index Total Return. CPER issues units that may be purchased and sold on the NYSE Arca. Source: iStockphoto Among the latest data released, Chinese producer price inflation increased to 6.9% in September compared with the year-ago level, beating 6.3% growth in August and the 6.4% forecast by economists.