Rio Tinto (RIO) said it retained its 51 percent stake in Ivanhoe Mines (IVN) by paying 935 million to maintain the position.
The acquisition of the shares came about from a shareholder rights offering by Ivanhoe.
Rio acquired 133.6 million additional shares of Ivanhoe as a result of the offering, paying $7 a share. The company now owns over 510 million shares of Ivanhoe.
Ivanhoe is developing the gigantic Mongolian mine Oyu Tolgoi, which holds huge deposits of gold and copper.
The offering was part of the strategy on the part Of Ivanhoe to finance the development of the mine.
Construction on the mine continues, with production scheduled to begin in the latter part of 2012, and commercial production to launch in 2013.
Ivanhoe closed Monday at $8.56, down $0.14, or 1.61 percent. Rio Tinto closed at $46.29, gaining $0.12, or 0.26 percent.