The sometimes criticised VGChartz reports that Rockstar's popular sandbox game Grand Theft Auto V has hit the 40 million mark, and as of December 20 the game had sold 40.56 million copies worldwide.
After it first was released in September 2013 to PlayStation 3 and Xbox 360, Grand Theft Auto V has broken many records. The release on the new generation of consoles last fall also boosted the sales, and it's fairly safe to predict that it will get yet another boost when it lands on PC in three weeks.
Almost 50 percent of the copies sold is on PlayStation 3 with 19.24 million, and the Xbox 360 version is a good number two with 17.79 million sold. So far it looks like Sony's plattforms are well ahead, as the number for PlayStation 4 is 4.73 million copies to Xbox One's 1.81 million.
It should be said that VGChartz use matemathical methods to estimates sales so it is by no means an official number, still it is very likely a good ballpark figure.