Diablo III has sold more than 12 million copies worldwide as of December 31, 2012.
Activision confirmed the figure as part of its Q4 FY2013 financial results today, in which it reported a record year for the publishing giant.That's up around 2 million sales since the company reported 10 million copies sold in November, 2012.
Activision notes that Diablo III was the "#1 best-selling PC game at retail" the calendar year 2012 in North America and Europe, "breaking PC game sales records".

http://www.computerandvideogames.com...les-worldwide/