Britain blocks Microsoft’s $69 billion acquisition of Activision Blizzard

Britain’s top competition regulator on Wednesday moved to block Microsoft’s acquisition of video game publisher Activision Blizzard.

The measure marks a major blow for the U.S. tech giant, as it seeks to convince authorities that the deal will benefit competition. Microsoft said it plans to appeal the decision.

Shares of Activision Blizzard slumped nearly 10% in U.S. premarket trading.

The U.K. Competition and Markets Authority said it opposed the deal as it raises competition concerns in the nascent cloud gaming market. The CMA previously held concerns about competition in games consoles being undermined but ruled...