Although a prime broker can often execute trades themselves on behalf of their clients, there are specialists executing brokers that may perform this task better to achieve better price or greater certainty of execution depending on the market or security. In these situations, the prime brokerage client may decide to engage with the executing broker for the trade initially, and then direct the settlement of that trade to their prime broker after the executing broker has helped them find a counterparty to trade with. In this example, the securities buyer places a buy order with the executing broker to buy 10,000 XYZ shares at $9 per share. The executing broker then goes out into the market and fulfills their role by finding another party who's willing to sell the 10,000 XYZ shares for $9. Earning themselves trading commission in the process. The client, the original securities buyer then in this example, tells the executing broker to direct this trade to the prime broker. The prime broker will be the one to match trades with the counterparty and to arrange the payment of $90,000 and the receipt of the 10,000 shares. The purpose of this is that the prime broker acts as a hub for its client or the home base where everything gets centralized. Having a prime broker arrangement does not preclude a client from using the services of other brokers for functions they may perform better than their prime broker, but then the outcome of these trades provided by other brokers are then centralized back to your prime brokerage home base. In a case like this where external executing brokers are used, the trading commissions would go to the executing broker and the client would have to pay a separate settlement fee or clearing fees to their prime broker for settling the trade. This separation of fees would be combined if you were to use your prime broker as the executing broker, and you may only see a single fee, but it does not mean the overall transaction end to end would be cheaper since that singular fee would likely be higher to reflect them acting as both the executor and settler of the trade.