Abstract: In a computer implemented currency trading support system trades are provided to a third party (400) for settlement, and at least one of the parties (1) has a checking system (102) at which trades are checked individually. A method is described in which one or both of the parties receives data relating to individual agreed trades, identifies trades involving the same currency and the same counterparty and aggregates them into a single aggregate trade corresponding to a plurality of individual trades. The data relating to trades is then passed directly to the third party settlement system and the checking system receives data relating to any aggregate trades resulting from the aggregating step as well as data relating to the corresponding individual trades.