I'm sure you know this, but for others reading this who are novices at finance / trading, like I am - the gotcha here is that while the strategy may be symmetric, the risk is not - when buying a stock, there is a floor to how much money you can lose (the price you paid for the stock), while with short-selling, there is no such floor, since the price can rise to any amount and increase your losses to infinite. I believe that traders will use hedges to account for this, however, these hedges will eat into your profits if they are not exercised (but may save your bacon if they are!).