Pittsburgh--MetalSite, an early e-marketplace entrant, has teamed with powerful newcomer MetalSpectrum, Atlanta, in a deal that stops short of a merger but finds the two industry marketplaces sharing customers and cooperating on supply chain applications. MetalSite was a so-called ``coalition'' marketplace before such constructs became popular. Its investors include big metal companies, among them Bethlehem Steel Corp., LTV Steel, Ryerson Tull, Steel Dynamics Inc., Weirton Steel and Internet Capital Group. Up to now, its competition has come from independent Net market e-Steel Corp. But the launch of MetalSpectrum earlier this year brought on a new powerful foe, with the backing of companies such as Alcoa Inc. and Kaiser Aluminum. MetalSite and MetalSpectrum fit together well. MetalSite focuses mainly on prime and formed steel, while MetalSpectrum aims to trade mainly aluminum, stainless steel, copper and brass.