Most commodity ETFs own the physical commodity. SPDR Gold Shares () owns over 40 million ounces of gold in trust, iShares Silver Trust () owns 18,000 tons of silver, Aberdeen Standard Physical Palladium Shares () owns almost 200,000 ounces of palladium, and Aberdeen Standard Physical Platinum Shares ETF () owns over 1.1 million ounces of platinum. However, many ETFs such as the United States Oil Fund by United States Commodity Funds () only own futures contracts, which may produce quite different results from owning the commodity. In these cases, the funds simply roll the delivery month of the contracts forward from month to month. This does give exposure to the commodity, but subjects the investor to risks involved in different prices along the term structure, such as a high cost to roll. They can also be index funds tracking commodity indices.