Ivanhoe Mines Ltd. rose 16 percent on Tuesday, after Rio Tinto Group, its partner in the Oyutolgoi project, increased its stake in Ivanhoe to 49 percent. That’s Ivanhoe’s biggest rise in more than two years.

According to Bloomberg News, Ivanhoe rose C$2.42 to C$17.42 at 4 p.m. in Toronto Stock Exchange trading. Shares of the Canadian company had climbed 26 percent earlier in the day.

The rise follows a 9.1 percent fall on Monday, following reports that Mongolia wants to renegotiate the company’s agreement to develop the Oyutolgoi mining project.

The Mongolian government wants to increase its stake in the project to 50 percent from the 34 percent agreed upon in a 2009 agreement with Ivanhoe and Rio Tinto. By agitating to change the agreement, analysts say Mongolia risks alienating potential foreign investors.