A credit data processing system for controlling trades in an electronic trading system according to credit arrangements, comprising a computer-readable storage medium, an interface to an electronic trading system and a credit data processor. The computer-readable storage medium stores information representing the credit relationship network, including a plurality of credit entities in the network and a plurality of credit relationships existing between at least some of those credit entities. The system uses preferred counterparty rankings provided by the participating credit entities to determine and select the optimal credit paths to use for booking multiple-legged trades between credit entities even though the credit entities may not have a direct credit relationship. The system then checks each leg of the selected optimal credit path to verify that, taking into account the current net open positions on that leg, executing the trade required on that leg to carry out the proposed deal will not cause a credit limit associated with that leg to be exceeded. If the credit limit of any leg in the selected optimal credit path is exceeded, then the system will repeatedly try to find viable credit path based on the preferences specified by the credit entities involved in the trade, until a viable credit path is found or it is determined that no credit path that can accommodate the proposed deal without exceeding a credit limit currently exists.