<p>An electronic transaction management system has at least some sellers associated with agencies. Information is provided for each agency to indicate whether the agency is prepared to offer sellers associated with the agency to buyers associated with other agencies and the terms of any such offer. A buyer interface is used to receive a purchase inquiry from a buyer, and seller offer data is provided to the buyer for a plurality of sellers. The seller offer data presented to the buyer takes into account the terms of said offer of sellers associated with an agency to buyers associated with other agencies. This system allows middlemen to operate in an online spot market. This is achieved by enabling agencies in a market sector to present their buyers and sellers with the agency's own version of such a market but draw on the buyer/seller relationships enjoyed by other agencies using the system. Agencies can operate their own market which is a distinct part of a wider market.</p>
