The Federal Trade Commission has officially sued Microsoft in an attempt to stop the company’s $69 billion acquisition of video game publisher Activision Blizzard. The suit, which was filed Thursday, December 8, claims that the deal would make Microsoft too strong a competitor in the video games industry, and would ultimately suppress competition. The lawsuit comes as little surprise, as Politico indicated the FTC was likely to file antitrust claims against Microsoft late last month.

As reported by The Washington Post, the lawsuit represents the FTC’s “most significant effort to rein in consolidation in the tech industry.” The news follows prominent academic and tech critic Lina Kahn’s appointment to the FTC chair, and falls in line with her mission of “ushering in a new era of antitrust enforcement.” Microsoft has reportedly not seen such a “serious regulatory threat to its business” in over 20 years, when the Department of Justice brought an antitrust lawsuit against the company.

According to The Washington Post, this lawsuit could put a stop to Microsoft’s purchase of Activision Blizzard. Announced earlier this year, this purchase would give the company ownership over franchises such as Call of Duty, Diablo, Overwatch, League of Legends, and Candy Crush.

Throughout this process, Microsoft has repeatedly attempted to assure the public that exclusivity is not its aim with this acquisition. The company has reportedly guaranteed that the Call of Duty franchise will remain on PlayStation platforms for a decade, and will also come to Nintendo consoles if the deal goes through. However, the FTC claims the acquisition still gives Microsoft an unfair advantage and could “dampen innovation in these more nascent gaming markets.”