A short sale is a common type of trade in the financial world. It involves selling an asset that a trader does not own. The trader borrows the asset, then—by a specified later date—buys it back and returns it to the asset's owner. The investment philosophy is that the borrowed asset will decline in price and the investor will earn a profit by selling at a higher price and buying back at the lower price. Selling short is done on margin and is a risky endeavor due to its unlimited potential for loss.

In determining who benefits from lending shares in a short sale, we first need to clarify who is doing the lending in a short sale transaction. Many individual investors think that—because their shares are the ones lent to the borrower—they will receive some benefit, but this is not the case.

Benefits From Lending Shares

When a trader wishes to take a short position, they borrow the shares from a broker without knowing where the shares come from or to whom they belong. The borrowed shares may be coming out of another trader's margin account, out of the shares held in the broker's inventory, or even from another brokerage firm. It is important to note that when the transaction has been placed, the broker is the party doing the lending, not the individual investor. So, any benefit received (along with any risk) belongs to the broker.

The broker does receive an amount of interest for lending out the shares and is also paid a commission for providing this service. In the event that the short seller is unable (due to a bankruptcy, for example) to return the shares they borrowed, the broker is responsible for returning the borrowed shares. Though this is not a huge risk to the broker due to margin requirements, the risk of loss is still there, and this is why the broker receives the interest on the loan.

In the event that the lender of the shares wishes to sell the stock, the short seller is generally not affected. The brokerage firm that lent the shares from one client's account to a short seller will usually replace the shares from its existing inventory. The shares are sold and the lender receives the proceeds of the sale into their account. The brokerage firm is still owed the shares by the short seller. 

The main reason why the brokerage—not the individual holding the shares—receives the benefits of lending shares in a short sale transaction can be found in the terms of the margin account agreement. When a client opens a margin account, there is usually a clause in the contract that states that the broker is authorized to lend—either to itself or to others—any securities held by the client. By signing this agreement, the client forgoes any future benefit of having their shares lent out to other parties.

The Bottom Line

Short selling is a risky trade but can be profitable if executed correctly with the right information backing the trade. In a short sale transaction, a broker holding the shares is typically the one that benefits the most, because they can charge interest and commission on lending out the shares in their inventory. The actual owner of the shares does not benefit due to stipulations set forth in the margin account agreement.