Peabody Energy has acquired a 5.1% stake in China-based Winsway Coking Coal for an undisclosed sum.
The move is part of a series of purchases of Winsway's shares on the Hong Kong Stock Exchange.
Currently, Peabody and Winsway are joint venture partners that hold coal and uranium licences in Mongolia.
The two companies are also conducting an active exploration programme in the South Gobi region and throughout the country.
The companies recently entered into a non-binding memorandum to establish a joint venture market coal in China and the Asia-Pacific region.
Winsway Coking Coal Holdings is a supplier of imported coking coal and one of the single largest offtakers of Mongolian coking coal into China in terms of volume.
Peabody Energy is the world's largest private-sector coal company and a global leader in clean coal solutions.