NEW YORK — Rupert Murdoch, the 92-year-old media magnate who created Fox News, is stepping down as leader of both Fox’s parent company and his News Corp. media holdings.

Fox said Thursday that Murdoch would become chairman emeritus of both companies. His son, Lachlan, will become News Corp. chairman and continue as chief executive officer of Fox Corp.

Lachlan Murdoch said that “we are grateful that he will serve as chairman emeritus and know he will continue to provide valued counsel to both companies.”

Besides Fox News, Murdoch started the Fox broadcast network, the first to successfully challenge the Big Three of ABC, CBS and NBC. He is owner of the Wall Street Journal and the New York Post.

Murdoch is a force in the conservative world, where Fox News Channel has profoundly influenced television and the nation’s politics since its start in 1996.

Murdoch vowed in a letter to employees that he would remain engaged at Fox.

“In my new role, I can guarantee you that I will be involved every day in the contest of ideas, Murdoch wrote. “Our companies are communities, and I will be an active member of our community. I will be watching our broadcasts with a critical eye, reading our newspapers and websites and books with much interest.”

There was no immediate word on why Murdoch’s announcement came now. Ironically, it is the week author and Murdoch biographer Michael Wolff is publishing a book, “The End of Fox News,” speculating on what will happen to the network when the patriarch is gone.