Abstract: The invention relates to a system for operating a reverse auction for a number of users. The system has a server with a clock, reverse auction data including a start time and a subscriber list, the server in communication with a plurality of user devices of a plurality of users via a data communication network. The server is configured to transmit the auction data to one or more users in the subscriber list, receive data from a user in the subscriber list indicative of the user viewing the auction, create an active user list as a subset of the subscriber list based on data received from each member indicative of the user viewing the reverse auction, synchronise each user device in the active user list with the clock, receive data from a user in the active users list indicative of participating in the reverse auction, create a participant users list as a subset the active users list and receive bid data and clock data from a user device in the participant users list.