Abstract: A first participating entities prepares a transaction offer notice on a data processing system. The transaction offer notice is stored in a database of such notices on a server system which is available to entities participating in the system. Transaction notices contained within the server system's database are available to a user community over the Internet and form the basis of a trading platform. Users are able to search the database for transaction offer notices that satisfy a set for search criteria, and are able to electronically negotiate with the offeror with respect to transaction parameters and other terms and conditions until the transaction is acceptable to both parties. The original transaction offer notice is retained in the database and is further available to the user community while negotiations are proceeding.