An apparatus for storing a set of events, is provided, the apparatus comprising one or more circuitry configured to: receive an electronic message comprising information of a first event between a first party and a second party, the first event being initiated by the first party; determine whether a record of the first event exists in a first storage unit; wherein when it is determined that the record of the first event does not exist, the one or more circuitry is configured to: determine whether any subsequent events between the second party and a third party are initiated by the second party within a predetermined time of the first event; and store an association between the second party and a first set of events, the first set of events comprising the first event and the subsequent event, in a second storage unit, when the subsequent event is initiated within the predetermined time.