ETFs such as USO are not holding actual oil unlike gold ETF GLD which actually holds gold bars. USO uses futures contracts to track oil prices and they are pointing up or using fancy terms in contango now. USO fund each month has to sell front contract and buy more expensive next month contract. Because of that effect when last year oil prices dropped from $53.49 to $37.13 or drop of 30% the USO ETF went down from $20.36 to $11.00 or drop of 46% which is 16% difference thanks to contango and expenses. Looking forward into 2016/17 (here for example) 20% increase from $37 to $44.21 is already priced in into future contracts so if oil raises less than 20% USO investors will lose money. Oil needs to rally at least 25% to $46 for investment in USO to break even if you include expenses.