B2B marketplaces have suffered a severe blow with the announced closure of two exchanges covering chemical and medical products.US-based Ventro is to shut down Chemdex and Promedix at the end of this year. At least 235 people will lose their jobs and the company expects the cost to be as much as $410m. Cutting the two exchanges will reduce operating costs by 50 per cent. Earlier attempts to sell the exchanges had not met with offers to satisfy the board. Ventro intends to refocus by supplying technology and services to, rather than directly managing, the marketplaces. Ventro expect vertical industries to set up their own B2B arenas. The European operation will be forced to lose two of its ten staff, though Mark Lane, VP of European marketing, said the company would be looking to recruit ecommerce specialists as the services business grows. Chemdex and Promedix had not begun European operations.