U.K. Flexes New Muscle in Antitrust Probes Over Microsoft and Amazon

LONDON—The U.K’s antitrust agency opened probes into Microsoft proposed takeover of Activision Blizzard and into Amazon Inc.’s business practices, solidifying the U.K. as a new regulatory power that Silicon Valley must reckon with.

The U.K. Competition and Markets Authority said Wednesday that it was investigating whether Microsoft’s $75 billion bid for Activision, the videogame giant behind “Call of Duty” and “World of Warcraft,” would reduce competition in Britain. The probe follows a similar investigation in the U.S. from the Federal Trade Commission.