USO is an ETF based off of a basket of futures contracts. The problem with owning USO is that there is basically inefficiency when rolling futures contracts and

USO is an ETF based off of a basket of futures contracts. The problem with owning USO is that there is basically inefficiency when rolling futures contracts and there is a some decay in the price. If you truly want to play in oil, best to use the futures themselves. Futures are the highest leverage instruments available, so be careful to note their size, but there is nothing more risky about futures than the equivalent notional value of stocks.