Short selling - lender's motivation

Question

It is not clear to me how the lender of the shares profits at all from short selling.

• The broker profits by lending the shares to someone else and then getting paid interest
• The short seller profits by buying the shares back at a lower price and pocketing the difference (minus the interest paid to the broker)

How does the original owner of the shares profit from the transaction ? Who are those lenders ? What are their motivations ?

In case the short seller is actually forced to buy the shares back at a higher price (e.g. short squeeze) I guess the lender profits. But was if short selling is successful from the borrower point of view ?

Follow-up question: what prevents the broker lending the shares for a very short time (less than a day), pocketing the interest and returning the lenders their shares without much change in share price (because borrowing period was very short). What prevents them from doing that many times a day ?

Answer 1

Oftentimes, the lender (the owner of the security) is not explicitly involved in the lending transaction. Let's say the broker is holding a long-term position of 1MM shares from Client A. It is common for Client A's agreement with Broker A to include a clause that allows the broker to lend out the 1MM shares for its own profit ("rehypothecation"). Client A may be compensated for this in some form (e.g. baked into their financing rates), but they do not receive any compensation that is directly tied to lending activities.

You also have securities lending agents that lend securities for an explicit fee. For example, the borrower's broker may not have sufficient inventory, in which case they would need to find a third-party lending agent. This happens both on-demand as well as for a fixed-terms (typically a large basket of securities). SLB (securities lending and borrowing) is a business in its own right.

I'm not sure I follow your follow-up question but oftentimes there is no restriction that prevents the broker from lending out shares "for a very short time". Unless there is a transaction-based fee though, the number of times you lend shares does not affect "pocketing the interest" since interest accrues as a function of time.

Answer 2

As the other answer said, the person who owns the lent stock does not benefit directly. They may benefit indirectly in that brokers can use the short lending profits to reduce their fees or in that they have the option to short other stocks at the same terms.

Follow-up question: what prevents the broker lending the shares for a very short time (less than a day), pocketing the interest and returning the lenders their shares without much change in share price (because borrowing period was very short). What prevents them from doing that many times a day ?

Lack of market.

Short selling for short periods of time isn't so common as to allow for "many" times a day. Some day traders may do it occasionally, but I don't know that it would be a reliable business model to supply them. If there are enough people interested in shorting the stock, they will probably want to hold onto it long enough for the anticipated movement to happen.

There are transaction costs here. Both fees for trading at all and the extra charges for short sale borrowing and interest. Most stocks do not move down by large enough amounts "many" times a day. Their fluctuations are smaller. If the stock doesn't move enough to cover the transaction fees, then that seller lost money overall. Over time, sellers like that will stop trading, as they will lose all their money.

All that said, there are no legal blocks to loaning the stock out many times, just practical ones. If a stock was varying wildly for some bizarre reason, it could happen.