Another layer of complexity can be added to the ecosystem since prime brokers can borrow not only from their own client accounts, i.e. their inventory, but at times they may have a borrower client that wants to borrow a security that they as the prime broker do not have in inventory across all of their client accounts. To introduce some terminology, this would be called trying to get a locate on that security that you're looking to borrow. In these instances, the prime broker may be able to borrow that security, but from another prime broker's inventory, this means another prime broker is their lender counterparty, rather than a client's account as the counterparty. What ends up happening here is that the prime broker they borrow from themselves they will have to borrow that security from one of their client accounts. This creates a chain of borrowing with more middlemen involved that raises the costs of borrowing for the end client's borrower. As you can see in this example, if both the prime brokers each demand a 1% net borrow fee for the service they're providing, and the ultimate lender to the stock is an institutional client with a 2% borrow fee, the overall borrow fee increases to 4%, 1 percentage point higher than if their prime broker could have sourced the security from their own client inventory. The point to take away from this is that if the securities borrower wishes to borrow a more unusual, less widely held security, which is less likely to be held by their prime borrower, then the higher the borrow cost, they are likely to pay.