1. A system for prematurely terminating outstanding OTC derivative transactions between a plurality of parties before designated maturity dates of the derivative transactions, the system comprising: a processing station arranged to receive transaction data describing a plurality of OTC derivative transactions including the designated maturity date of each transaction, from a plurality of transaction parties via a communications network, the processing station including a processor and comprising: a linking module (i) for linking together different versions of the same OTC derivative transaction, each version being received from a different party to that transaction, or (ii) for receiving previously linked groups of the different versions of the same OTC derivative transaction; an analysis module for determining a set of linked OTC derivative transactions between a plurality of different transaction parties, wherein each transaction party in the set has both debts and claims towards other parties in the set; a calculation module arranged to calculate an aggregated value of each set of linked OTC derivative transactions and arranged to select the set of linked OTC derivative transactions which has an aggregated value within party-specified tolerance limits acceptable for executing a premature termination, at a date at which there is no prescribed value and no prescribed method of determining a value at which the termination should take place, and at which there is no obligation for the parties to make a premature termination of the linked OTC derivative transactions of the selected set; and an execution module for executing a premature termination of the selected set of linked OTC derivative transactions, prior to their respective designated maturity dates.