Share your insights or perspective on the financial matter presented in the input.

Why does short selling require borrowing?
It's actually quite simple. You're actually confusing two concept. Which are taking a short position and short selling itself. Basically when taking a short position is by believing that the stock is going to drop and you sell it. You can or not buy it back later depending on the believe it grows again or not. So basically you didn't make any profit with the drop in the price's value but you didn't lose money either.  Ok but what if you believe the market or specific company is going to drop and you want to profit on it while it's dropping. You can't do this by buying stock because you would be going long right? So back to the basics. To obtain any type of profit I need to buy low and sell high, right? This is natural for use in long positions. Well, now knowing that you can sell high at the current moment and buy low in the future what do you do? You can't sell what you don't have. So acquire it. Ask someone to lend it to you for some time and sell it. So selling high, check.  Now buying low? You promised the person you would return him his stock, as it's intangible he won't even notice it's a different unit, so you buy low and return the lender his stock. Thus you bought low and sold high, meaning having a profit. So technically short selling is a type of short position. If you have multiple portfolios and lend yourself (i.e. maintaining a long-term long position while making some money with a short term short-term strategy) you're actually short selling with your own stock. This happens often in hedge funds where multiple strategies are used and to optimise the transaction costs and borrowing fees, they have algorithms that clear (match) long and short coming in from different traders, algorithms, etc. Keep in mind that you while have a opportunities risk associated.  So basically, yes, you need to always 'borrow' a product to be able to short sell it. What can happen is that you lend yourself but this only makes sense if: