NEW YORK: Walt Disney Co. on Thursday agreed to buy key film and television operations of 21st Century Fox in a $52.4 billion stock deal that could reshape the media-entertainment world and step up a challenge to Netflix and emerging tech platforms.

The blockbuster transaction also vastly reduces the Fox media empire built by Rupert Murdoch, leaving the 86-year-old tycoon and his two sons with a more tightly focused group comprised of the Fox broadcast network, Fox News Channel and sports channels.

The deal will see Disney acquire the vaunted Fox Hollywood film and television studios, cable entertainment networks and international TV businesses, bringing popular entertainment properties including X-Men, Avatar, The Simpsons, FX Networks and National Geographic into Disney's portfolio.

"The acquisition of this stellar collection of businesses from 21st Century Fox reflects the increasing consumer demand for a rich diversity of entertainment experiences that are more compelling, accessible and convenient than ever before," said Disney's chief executive Robert Iger in a statement.

Iger, who was previously expected to step down in 2019, will now stay on through 2021.

Disney has been seen as trying to bolster its Hollywood and television positions by getting the Fox library of content to strengthen its arsenal against Netflix and other rivals.

The rise of streaming services and the so-called cord-cutting movement against cable television, together with declining advertising revenue, have contributed to a rapidly changing landscape for media companies.

Disney, which owns the ABC television network, ESPN and has major studios in Hollywood, is set to launch its own streaming services aimed at competing against Netflix and Amazon.

The deal also gives it a controlling interest in Hulu, another popular streaming service.

Analysts have said the deal could face considerable scrutiny by antitrust regulators because of the tie-up between two of the largest film and television groups.

The news comes as another major media deal, between AT&T and Time Warner, has been challenged in an antitrust filing by the US Justice Department.

Prior to the deal going through, 21st Century Fox will transfer the Fox Broadcasting network and stations, Fox News Channel, Fox Business Network, FS1, FS2 and Big Ten Network into a newly listed company that will be spun off to its shareholders.

Rupert Murdoch said in the statement issued by the companies: "We are extremely proud of all that we have built at 21st Century Fox, and I firmly believe that this combination with Disney will unlock even more value for shareholders as the new Disney continues to set the pace in what is an exciting and dynamic industry."

21st Century Fox shareholders will receive 0.2745 Disney shares for each 21st Century Fox share they hold under the deal.