BOIL is a leveraged ETF, and like all geared products, is intended to be held only short periods, its not appropriate for buy-and-hold investors. BOIL provides 2x the return of a futures-based natural gas index on a daily basis. Daily compounding of returns can lead to the fund's returns varying significantly from the 2x exposure to the index over longer holding periods. Index returns reflect both the price changes on its futures contracts as well as any gain or loss from rolling those futures contracts. BOIL is a tactical tool, so trading costs and volume matter.