Abstract: There is disclosed an electronic trading system and associated methods adapted to automatically match submitted orders on the basis of price, quantity limitations, and lines of credit defined by potential counterparties. Lines of credit are divided into time based tranches relating to the maturity of an instrument to be traded, and a number of schemes are used to manage the tranches in order to improve control and use of remaining credit, which can be replenished manually or automatically. Traders are grouped into desks, and orders submitted by a trader may be matched on behalf of any of several credit centers defined per trader desk. Lines of credit may be held in various ways such as at the level of counterparty trading organizations, and at the level of counterparty credit centers.