Microsoft's ($MSFT@US) proposed $75 billion deal to buy game maker Activision Blizzard has been rejected by the U.K.’s antitrust regulator, the Competition and Markets Authority. The CMA claimed that the deal poses a threat to competition in the UK gaming industry and rejected Microsoft's proposal to ease competition worries. The US Federal Trade Commission and European Union are also investigating the deal, which could prevent the deal from closing as the videogame industry is complex and global. Microsoft has said it will appeal the decision, and the European Commission's antitrust regulator has set a deadline of May 22nd for its own ruling, while the FTC's administrative court will hear the case in August.