Focusing on the coal mining business, SMM has been a foreign investment company since 2007. On March 23, 2017, PT United Tractors, Tbk. (UNTR) and PT Pamapersada Nusantara through its subsidiary, PT Tuah Turangga Agung (TTA), has officially acquired 80.1% of its shares. With this acquisition, SMM expands its mine ownership in Indonesia.