Oracle has tried to persuade European competition regulators that their plan to prohibit its takeover of rival software firm PeopleSoft is based on too narrow a definition of the market.
The European Commission, which is leading an in-depth investigation of the proposed deal, told Oracle last month that it is concerned that the takeover will leave only two serious players in Europe's market for software that helps run businesses: Oracle and Germany's SAP.
The commission fears that the PeopleSoft deal would allow the two remaining competitors to squeeze the market to the detriment of consumers.
Oracle told the commission that it should be looking at the market for software tailored for smaller firms.
Microsoft's wholly owned Danish subsidiary, Navision, and Baan, a division of SSA Global Technologies, compete in the market for enterprise software for small firms.
Other firms such as Siebel Systems build specialised software for companies, such as customer relationship management tools, but none apart from Oracle, PeopleSoft and SAP make all-round packages for multinationals.
"The market supplying large multinational clients is completely separate from the market for smaller firms, or for specialist products," said one person opposed to the Oracle-PeopleSoft deal. "The demand is separate, as is the supply," he added.
The US Department of Justice reached this conclusion last month and filed suit against Oracle to block the deal on antitrust grounds, using similar market definitions to the ones being applied in the European case. The case will be heard in June.
The deadline for European Commission's decision is 11 May.
Paul Mellor writes for IDG News Service