By exercising its right to acquire shares in the exploration company led by Robert Friedland, Rio Tinto upped its stake to 48.5% and, under the current deal between the two companies, can boost the stake further to 49%.
See http://www.mineweb.com/mineweb/view/mineweb/en/page504?oid=134144&sn=Detail.
For background on the relationship between Ivanhoe and Rio Tinto, see http://www.minesandcommunities.org/article.php?a=11098