Britain’s antitrust watchdog said on Wednesday it had started an investigation into Microsoft Corp’s $68.7 billion deal to buy “Call of Duty” maker Activision Blizzard Inc.

The Competition and Markets Authority (CMA) said it had until Sept. 1 to make its phase 1 decision on whether the deal between the U.S. technology company and video-game maker Activision would reduce competition in the UK.

The phase 1 investigation by the CMA will either lead to the deal being cleared or will move to a more in-depth phase 2 probe.

Both Microsoft and Activision did not immediately respond to Reuters’ requests for comments.

In the biggest gaming industry deal in history, Microsoft in January said it was buying Activision Blizzard. According to Refinitiv data, the Microsoft-Activision deal would be the largest all-cash acquisition on record.