"We have provisionally found that if the Fox/Sky merger went ahead as proposed, it would be against the public interest," Anne Lambert, chair of the independent investigation group said. "It would result in the Murdoch family having too much control over news providers in the UK, and too much influence over public opinion and the political agenda." Murdoch already holds a 39 percent stake in Sky. He tried to buy the remaining piece in 2010, but abandoned the deal after News Corporation (which is now 21st Century Fox) was swept up in a hugely damaging phone hacking scandal.

The CMA is consulting on its decision and has proposed business "remedies" that could change its mind. These are unlikely to appeal to Murdoch and 21st Century Fox, however. The first is a complete ban on the transaction, which would preserve the status quo. The CMA is worried, however, that such a move would encourage Sky to close Sky News — if the company's newsroom disappeared, the concerns about "media plurality," or a journalistic monopoly, would arguably go with it. The second is a spin-off or divestiture of Sky News, thereby limiting the impact of a takeover.

The proposed merger has already been approved by Ofcom and the European Commission. Karen Bradley, then culture secretary, referred the bid to the CMA in September last year. Since then, 21st Century Fox has agreed to sell its media empire to Disney for $52 billion. That has complicated the CMA's decision. The regulator says the Disney deal is unlikely to go through before its own inquiry has been completed. As a result, it cannot assume that the transaction will be approved and make recommendations accordingly. It can, however, assess the possible implications and use them to guide its business concessions or "remedies."

The CMA has until May 1st, 2018 to finalise its report. The regulator will submit its findings to Matt Hancock, the secretary of state for Digital, Culture, Media and Sport, who will then make the final decision.