Peabody Energy Corp ( BTU.N ), the largest U.S. coal producer, may have to seek bankruptcy protection, the company said in a regulatory filing on Wednesday, citing poor economies in countries that import coal and other factors battering the coal industry. Its shares fell 46 percent to $2.16. Falling demand for coal, tougher environmental controls and cheaper natural gas have pushed several big coal miners, including Arch Coal Inc ACIIQ.PK, into bankruptcy in the past year. Peabody, which flagged the possibility of bankruptcy under the “risk factors” section of a filing with the U.S. Securities and Exchange Commission, said it had decided to skip $71.1 million in interest payments, kicking off a 30-day grace period. ( 1.usa.gov/22jEJnJ ) The company, said there was “substantial doubt” about its ability to continue as a going concern. It cited stagnating economic growth in major coal importers and the potential for additional regulatory […]