BioShock Infinite has crossed 4m sales since launching in March, according to Take-Two.
Company CEO Strauss Zelnick mentioned the milestone for 2K and Irrational Games' hit title during a call to investors, following the release of the publisher's latest financial report.
"BioShock Infinite is North America's best-selling multiplatform release so far this year, according to NPD," Zelnick said.
"The title has crossed the 4 million units selling mark, and we expect it to become the top-selling release in the BioShock franchise."
The announcement follows the reveal of two new pieces of DLC for the game – one that looks to expand directly upon the game's setting, and the other that brings the protagonists of Infinite to the dark depths of Rapture from the first BioShock games.