New York--In a blockbuster announcement, IBM Corp., i2 Technologies and Ariba Technologies said Wednesday that they'll join forces to provide the infrastructure for business-to-business marketplaces that range from buying to supply chain management. Under terms of the agreement, Ariba will integrate software developed by IBM to manage $45 billion in purchasing with its requisitioning platform. Meanwhile, i2 Technologies will provide its supply-chain planning software to the alliance. The move means the trio will chase Oracle Corp., which claims to cover the spectrum of business buying with its databases and Web server software. American Express, which endorsed the deal, said it was developing a payment system for use by the alliance's trading networks. Chevron Corp., Enron Corp. and Bristol-Myers Squibb Co. were among a slew of companies endorsing the alliance as customers.