The US Department of Justice recently sued to block AT&T's $85.4bn deal to buy Time Warner, on the basis that it will raise prices for consumers and competitors.
In the UK, Fox's proposed deal to buy the remainder of Sky is being already investigated by the Competition and Markets Authority (CMA), which is due to publish provisional findings in January.
The BBC understands that the Disney deal will not alter that CMA investigation.
Rupert Murdoch said: "If things go wrong, the existing [Sky] shares go to Disney. It will be up to them to decide what to do."
Fox is selling assets including its FX and National Geographic cable channels and media company Star India.
Disney also will buy Fox's stake in the Hulu video streaming service, giving it majority control of a competitor to Netflix.
Hulu is also partially owned by Comcast and Time Warner.
Paolo Pescatore, an analyst with CCS Insight, said: "The move will firmly establish Disney as one of the leading media companies in the world and puts it in a great position to compete head on with the threat posed by the web providers such as Amazon and Facebook." SkyMore