The nature of coal production has altered the structure of this industry to achieve more consolidation and as a result, fewer companies have continued to dominate this sector. In the United States, the four largest players, including Peabody Energy Corporation (NYSE:BTU), Arch Coal Inc (NYSE:ACI), Alpha Natural Resources LLC and Cloud Peak Energy Inc. (NYSE:CLD), have controlled more than half of the coal supply in the country.
Figure 1: United States coal production share by top four coal companies

The Energy Information Administration (EIA) reports that the four firms supplied a total of 575 million...

