I used to tell my boy scout personal management merit badge class that after thirty years of investing, I was sure of only one thing about markets. They go up and down. We just don't know when. When something like oil hits a new high, you know that the probability of it going higher is much lower than the probability of it going lower. So how do you profit from a decline in oil? If you use options, the option could expire before oil declines. You could short an oil stock, but the stock may move independently of the price of oil or other companies in the sector. You could buy a hedge fund, but the fees will kill you. If you short an ETF, it costs you very little, it is diversified, and you can hold it until the market moves, which, in time, it will.