Setting itself beyond the classic opposition between the vitality of private monetary practices and the ponderousness of public and regulatory intervention, this study of the Bourse and bill brokers in Rouen under the Ancien Régime describes how the city’s trade elite supervised commercial paper exchanges. The constitution of a trade enclosure for high-quality money and the effective submission of brokers to the power of the merchant court judges (Juges-Consuls) merged into the history of an institution, the juridiction consulaire (merchant court), which slowly managed to reinforce its legitimacy and power by way of the monarchy’s fiscal operations. In the eighteenth century, within a context of expanding banking exchanges, the merchant court established its control over banking and exchange brokerage. Discount credit, the core of the banking business, then developed in a very regulated brokerage regime. Among the different bans affecting their activities, one forbade the Bourse’s brokers—who were suspected of manipulating the market—from maintaining a cashier desk (tenir une caisse) and negotiating bills of exchange on their own account. Yet, Jacques Payenneville’s destitution in 1764 by the merchant court judges revealed that these bans were not respected and that, most of all, they hindered the discount market’s increasing demand for liquidity. Facing the development of exchanges and banking uses, the merchant court had to rearrange its regulations in order to integrate new uses and maintain the essentials: the trade elite’s power over its “servants” (commis).