The invention relates to an electronic data processing system for conducting auctions over a data network. A component of the system consists of an auction server, which is connected to the data network and which has an auction database for managing auction data records containing product description data and bid data. A number of bidder terminals are connected to the data network and comprise appropriate means for retrieving data from the auction database and comprise means for transmitting bid data to the auction server. The aim of the invention is to enable the effective and economical use of conventional internet auction platforms by product manufacturers and retailers in order to sell goods. To this end, the invention provides that the electronic data processing system is supplemented by a retailer server, which is connected to the data network, and by an intermediary server that is also connected to the data network. The intermediary server has a program controller with which auction data records are automatically put into the auction database according to production description data that are extracted by the intermediary server from corresponding product portfolio data records of the retailer server. The intermediary server uses its program controller to automatically create order data records for the auction data records.