NEW YORK (AP) — Disney CEO Bob Iger, who steered the company's absorption of Star Wars, Pixar, Marvel and Fox's entertainment businesses and the launch of a Netflix challenger, is stepping down immediately, the company said in a surprise announcement Tuesday.

The Walt Disney Co. named as his replacement Bob Chapek, most recently chairman of Disney's parks, experiences and products business.

"Did not see this coming -- Wowza," tweeted LightShed media analyst Rich Greenfield.

Iger will remain executive chairman through the end of his contract on Dec. 31, 2021. Besides leading the board, Iger said he will spend more time on Disney's creative endeavors, including the ESPN sports network, the newly acquired Fox studios and the Hulu and Disney Plus streaming services. He said he could not do that while running Disney on a day-to-day basis.

“It was not accelerated for any particular reason other than I felt the need was now to make this change," Iger said on a conference call with reporters and analysts.

Iger steered Disney through the successful purchases of Lucasfilms, Marvel, Pixar and other brands that became big moneymakers for Disney. Last year, the top five movies in U.S. and Canada theaters were all Disney movies, including two from Marvel and one from Pixar. With the Dec. 20 release of the latest “Star Wars" movie, Disney had seven movies that each sold at least $1 billion in tickets worldwide last year.

Iger's most recent coup was orchestrating a $71 billion purchase of Fox's entertainment business in March and launching the Disney Plus streaming service in November. That service got nearly 29 million paid subscribers in less than three months. In a statement, Iger said it was the “optimal time" for a transition.

Pivotal Research Group analyst Jeffrey Wlodarczak said Iger had implied he would stay until his contract ended in 2021.

"On the other hand, they just successfully closed the Fox deal and had an unquestionably successful launch of Disney Plus so maybe he felt earlier was better to hand off the reins," he said.

Colin Gillis, director of research at Chatham Road Partners, said the choice of Chapek seems solid because his parks division has had success.

Chapek said that while he has not led television networks or streaming services, his background in consumer-oriented businesses should help. Chapek and Iger both stressed that Disney would continue on the direction it had already been taking.

Disney is facing challenges to its traditional media business as cord-cutting picks up, meaning less fees from cable and satellite companies to carry Disney networks such as ABC, ESPN and Freeform. Disney's own streaming services require the company to forgo money in licensing revenue, although the company is betting that money from subscriptions will eventually make up for that.