The traditional view of the futures clearinghouse as an insurer that eliminates the need for customers to evaluate default risk is inaccurate. A clearinghouse member default in 1985 confirms that the clearinghouse only guarantees payment from member to member, not from customer to customer or member to customer. Thus, non-defaulting customers are subject to losses as a result of the action of individuals with whom thay have no contractual obligations. This study models the behavior of customers choosing a futures commission merchant (FCM) given the current legal position of the clearinghouse. In a single-period model with symmetric information, customers can eliminate their exposure to defaults of other customers or of their FCM only by choosing to trade through “boutique” (undiversified) FCMs. In practice, monitoring and rebalancing costs may impede the attainment of zero default risk. However, FCM diversification remains an important factor in customer choice of an FCM. When setting capital requirements, clearinghouses and government regulators need to consider the implications of diversification for both customer and market protection.