A method of and system for terminating or assigning outstanding OTC derivative transactions between a plurality of financial institutions (banks). The system comprises: a processing station arranged to receive transaction data describing a plurality of transactions from a plurality of banks via the Internet. The processing station comprises: a linking module for linking different versions of the same transaction received from different parties to that transaction; an analysis module for determining a set of linked transactions between a plurality of different banks, wherein each bank has debts and claims towards other banks in the set; a calculation module arranged to calculate an aggregated value of each set of linked transactions and select the set of linked transactions which has an aggregated value within bank-specified tolerance limits acceptable for executing a termination; and an execution module for executing a termination or assignment of the selected set of linked transactions.