The US' Federal Trade Commission will be handling the antitrust review of Microsoft's acquisition of Activision Blizzard.
The FTC is to investigate whether the purchase will harm competition instead of the US Justice Department, a source close to the matter told Bloomberg.
The publication pointed out that antitrust reviews can be the responsibility of either entity with the FTC usually "more aggressive" in its policing than the Justice Department.
The FTC sued to block Nvidia's $40 billion acquisition of chip manufacturer Arm, with recent reports saying the purchase could be abandoned.
A couple of weeks ago, the Justice Department and the FTC announced joint plans to revisit merger guidelines as there has been a surge in M&As over the last few years, Reuters reported.
Microsoft announced the acquisition of Activision Blizzard on January 18, in a deal worth $68.7 billion.