abstract:The roll yield is the yield that a futures investor captures when their futures contract converges to the spot price; in a backwardated futures market the price rolls up to the spot price, so the roll yield is positive, whereas when the market is in contango the price rolls down to the spot price, so the roll yield is negative. The spot price can stay constant, but the investor will still earn returns from buying discounted futures contracts, which continuously roll up to the constant spot price.
The PowerShares DB Oil ETF attempts to minimize the negative effects of contango by buying the contract month with the highest effective rollyield when necessary.