The CMA is to assess whether the merger is in the public interest.
The case was referred for the CMA's scrutiny by the UK culture secretary, Karen Bradley, after she said there were public interest concerns worth investigating about the impact the planned £11.7 billion deal could have on media plurality and on the attainment of the objectives of the broadcasting standards outlined in UK communications laws should Fox complete the takeover.
Reasoning for the referral of the case to the CMA was set out in a letter the UK government sent to Fox and Sky (7-page / 289KB PDF) on Wednesday.
The letter said that Bradley would expect the CMA to look at the extent of control the Murdoch Family Trust might have on Sky if the proposed transaction is completed compared to the level of control it has now.
Bradley previously said she that she was "not confident" that Fox's corporate governance arrangements were sufficient to ensure the company's compliance with UK broadcasting standards post-transaction, and also noted third party concerns about the potential 'Foxification' of Sky's news coverage should the takeover go ahead as currently planned.
The CMA is due to report back with its findings from its investigation in March, but its 24 week deadline for reporting could be extended by eight weeks in certain circumstances.