A data processing system to enable the formulation of multi-party investments contracts is disclosed. The system comprises input means by which an ordering party can input contract data relating to at least one phenomenon, the phenomenon having a range of future outcomes and a future time of maturity. The contract data further includes a set of probabilities of occurrence for each outcome in the range and a consideration due to a counterparty at or after the time of maturity. One or more counterparties can input registering data including a set of probabilities of occurrence for each outcome in the range. The system further includes a data processor that is operable to price and match a contract from the contract data and the registering data.