Supplier of durable medical equipment (DME) and prosthetics and orthotics (P & O), and former member, brought action under Sherman Act against administrator of closed network of suppliers of DME and P & O to enrollees in certain health-benefits plans that health insurer had offered to employees and retirees of three large employers alleging that support contract amounted to illegal exclusive-dealing arrangement, constituted refusal to deal with and boycott of former member, and attempt to monopolize DME/P & O market. The Sixth Circuit Court of Appeals held, among other things, that: competition as a whole had to suffer as result of closed network for order for excluded supplier, who lost anticipated income, to have antitrust standing; and a closed network did not have substantial share of relevant market.