The United Kingdom's antitrust regulator is concerned that Microsoft's blockbuster purchase of Activision Blizzard could create a monopoly in the nascent cloud gaming space. The Competition and Markets Authority (CMA), which began investigating the deal back in July, says that it's not yet reassured by the promises Microsoft has made to get the deal done. It feels that, once Activision is a part of Microsoft, the Xbox maker could use its "control over popular games like Call of Duty and World of Warcraft" to "harm rivals" by boxing them out of access to popular titles. Microsoft has already publicly committed not to hoard exclusives, (and said that Actiblizz's library isn't all that anyway) but sweet words haven't appeased the officials. In a statement, it said that it was giving Microsoft and Activision five days to submit proposals that would address its concerns.