As anyone who looked at commodity ETFs can attest, esspecially USO and UNG, they make for terrible investments as they don't track the prices of the physicals. Oil goes up but the oil ETF, USO, goes down. Same thing for UNG—surprise surprise the system was all but rigged for Wall Street. No shocker there for an industry that preys on the public and looks for ways to use it's clout to game systems and take advantage of market participants. Check this
article or more.