Smeags on 28 February 2011
2001: Philosopher's/Sorcerer's Stone: $974,733,550
2002: Chamber of Secrets: $878,643,482
2004: Prisoner of Azkaban: $795,634,069
2005: Goblet of Fire: $895,921,036
2007: Order of the Phoenix: $938,212,738
2009: Half-Blood Prince: $933,959,197
2010: Deathly Hallows Pt. 1: $948,886,193
With 3D showings and the inflated dollar, Deathly Hallows Pt. 2 will finally take down Philosopher's/Sorcerer's Stone as the highest grossing Harry Potter film. I doubt it will beat the first's ticket sales though.
