A hybrid cross-margining system is disclosed. The disclosed provides for both joint accounts, maintained by multiple exchanges, as well as non-joint accounts, whereby the system recognizes both intra-account offsets within the joint account and inter-exchange offsets between the joint account and accounts...http://www.google.es/patents/US7801810?utm_source=gb-gplus-sharePatente US7801810 - Hybrid cross-margining
