The purpose of a 12-month strategy will help protect futures investors from the problem of contango. Two weeks before the expiration of the nearest-month contract, the fund will roll forward another month, picking up the then-12-months-out contract.
Other examples of futures-based ETFs include: United States Natural Gas (NYSEArca: UNG), PowerShares DB Gold (NYSEArca: DGL) and iShares S&P GSCI Commodity-Indexed Trust (NYSEArca: GSG). [Risks and rewards of futures-based ETFs.]
For more information on ETFs, visit our ETF 101 category.
Max Chen contributed to this article.