The Commission authorized staff to file a complaint to block Arch Coal, Inc.’s proposed acquisition of Triton Coal Company, L.L.C. from New Vulcan Holdings, L.L.C. on grounds that the acquisition would increase concentration and tend to create a monopoly in the market for coal mined from the Southern Powder River Basin and in the production of 8800 British Thermal Unit coal. On April 1, 2004, the complaint was filed in the U.S. District Court for the District of Columbia. On June 13, 2005 the Commission announced that it was closing its investigation, saying that it will not continue with administrative litigation challenging the deal.