(Reuters) -- Fox News Channel anchor Megyn Kelly, a star of the U.S. cable network's highly rated prime-time lineup, has decided to leave to join NBC News in a broad role that includes hosting a one-hour daytime news show, NBC announced on Tuesday.
Kelly also will anchor a Sunday night news show and take part in the network’s special political programing and other big-event coverage, NBC News said in a statement.
The departure is a potential blow to Fox News, the top-rated cable news network, owned by Rupert Murdoch's 21st Century Fox. Just months ago, its founding chairman, Roger Ailes, left following sexual harassment allegations by several women.
Kelly was one of the accusers and detailed Ailes' behavior in her best-selling book, "Settle for More." Ailes has denied the allegations.
Fox News, which is known for a roster of conservative commentators such as Bill O'Reilly, remained at the top of cable news ratings amid the Ailes turmoil. The network delivered its highest annual viewership in its 20-year history in 2016.
Kelly, 46, played a large role in that success, with 2.7 million viewers on average for her prime-time show, "The Kelly File," second on Fox only to O'Reilly's program, "The O'Reilly Factor."
"I have decided to end my time at FNC, incredibly enriched for the experiences I've had," Kelly wrote on Facebook.
She became a subject of news stories after Republican presidential candidate Donald Trump attacked her as unfair for her questioning of him at a primary debate during the 2016 election campaign.
Fox made a bid to keep Kelly, offering her more than $20 million per year, according to an October report in Vanity Fair.
In a statement on Tuesday, Murdoch thanked Kelly for "her 12 years of contributions" to the network. "We hope she enjoys tremendous success in her career and wish her and her family all the best," Murdoch said.
Kelly will host her prime-time show on Fox News through Friday.
While her departure leaves a hole in the Fox News lineup, it comes at a time when the network needs to reinvent itself to appeal to younger viewers, said Pivotal Research analyst Brian Wieser.
Fox News, like many of its peers, has an older audience, with a median age of over 65, higher than MSNBC and CNN, whose viewers' median ages are 64 and 60, respectively, according to Nielsen data. Advertisers generally seek a much younger market.
"Their audience is aging," Wieser said. "The question now for investors is, What will Fox put in Kelly’s place?"
Some media buyers said they expected Fox to maintain strong ratings given interest in the White House transition and the network's other popular hosts.
Barry Lowenthal, president of agency The Media Kitchen, called Kelly's departure "neutral" for the network.
"Given Fox’s ratings dominance, they’ve shown that they’re bigger than any one anchor," he said.
Kelly joined Fox in 2004 as a Washington-based correspondent. Her decision to move to NBC News, a unit of Comcast Corp, was first reported by The New York Times.
While details about Kelly’s upcoming shows were scarce, she will be trying to succeed where high-profile news anchors have struggled. In recent years, Katie Couric and Anderson Cooper lasted just two seasons with syndicated daytime talk shows.
Kelly’s new NBC News colleague Brian Williams, meanwhile, saw his low-rated prime-time news magazine show, "Rock Center," end after only two years.
WHAT INSIDERS ARE SAYING
CNN's Reliable Sources provides a round-up of comments:
-- Former colleague: "If Hillary had won, would she have left Fox?"
-- Trump watcher: "This is a good thing for Trump… Fox's biggest Trump critic is gone…"
-- A Kelly fan inside Fox: "Her book title was 'Settle for More.' She's settling for less money and maybe less impact. But more freedom and more time with family..."
-- NBC News insider: "There was lots of excitement. The newsrooms were buzzing as soon as the news hit…"
-- Another NBCer: "Andy Lack now has a big shiny object to invest his attention in…"
-- Talent agent: "How is NBC News going to afford her?"
-- Rival TV exec who doubts NBC can deliver: "She's been sold a bill of goods."
-- WSJ's Joe Flint on Twitter: "Be wary the agency promising to make you an even bigger star. Ask Josh Elliott, Sam Champion and Katie Couric how it worked out..."
-- Another rival TV exec: "Daytime TV is a graveyard…"
-- Daytime TV veteran: "The only thing working in daytime right now is diversity. Wendy Williams. 'The Real.' Steve Harvey…"
-- Former colleague: "She was a corporate lawyer, and she conquered cable news, so I'm not betting against her…"
-- Friend of Kelly’s: "She really painfully deliberated about this over the holidays…"
-- Murdoch aide: "Rupert was not surprised…"
-- Network PR exec: "Smart call by Kelly and Leslee Dart, having Kelly write a letter on social media instead of a canned statement..."
-- Executive producer: "Does anybody remember Rock Center?" (If you don't, it wasBrian Williams' stab at a Sunday night news program...)
-- NYT's John Koblin and Michael Grynbaum in Wednesday's paper: "One winner in the sweepstakes for Ms. Kelly could be CNN, even though it did not succeed in recruiting her..."