PCgamesN reports that firm DFC Intelligence has come to the conclusion that with 3 million copies sold in nine months, Guild Wars 2 is the fastest selling MMO in that period of time after any game launch.
The firm actually uses the term "fastest-selling MMO of all time," but this is a strange point to make that declaration as it had sold 2 million within two weeks of launch last year. In any case, we will just have to trust them on this, because after declaring that SWTOR had sold two million copies shortly after its launch in 2011 EA never reported sales number for that game again, and now that it's F2P it never will. Firms like DFC tend to have access to data not publicly available, it should be noted.
In any case, and perhaps not coincidentally, NCsoft is holding a free Guild Wars 2 weekend starting next Friday.