Katie Couric is leaving her anchor post at "CBS Evening News" less than five years after becoming the first woman to solely helm a network TV evening newscast.

A network executive, who spoke on condition of anonymity because Couric has not officially announced her plans, reported the move to The Associated Press on Sunday night. The 54-year-old anchor is expected to launch a syndicated talk show in 2012 and several companies are vying for her services.

Couric's move from NBC's "Today" show was big news in 2006, and she began in the anchor chair with a flourish that September. She tried to incorporate her strengths as an interviewer into a standard evening news format and millions of people who normally didn't watch the news at night checked it out. But they drifted away and the evening newscast reverted to a more traditional broadcast.

After those first few weeks, the "CBS Evening News" settled into third place in the ratings and is well behind leader Brian Williams at NBC's "Nightly News" and second-place Diane Sawyer at ABC's "World News."

No departure date has been set for Couric. Her CBS News contract expires on June 4.

"We're having ongoing discussions with Katie Couric," said CBS News spokeswoman Sonya McNair on Sunday. "We have no announcements to make at this time. Until we do, we will continue to decline comment on rumor or speculation."

Said Matthew Hiltzik, Couric's spokesman: "Ditto."

Still, discussions are already under way about who will replace Couric on the evening newscast. Russ Mitchell, Scott Pelley and Harry Smith are among the internal CBS candidates, and new CBS News Chairman Jeff Fager is also expected to look outside the company.

Couric, who was on vacation last week, was reluctant to talk about her future when she appeared on fellow CBS host David Letterman's show on March 22. "Once you take that anchor chair, that's what you do," Letterman told her.

"Really?" Couric answered.

"Look at Walter Cronkite, look at Tom Brokaw, look at Brian Williams, look at Peter Jennings, look at all these people," Letterman said. "They get in it, they saddle up and they ride into the sunset."

Couric smiled widely and said she loved doing the evening news and was proud of her work, but made no future commitments. Despite the ratings problems, the "CBS Evening News" won the Edward R. Murrow Award as best newscast in 2008 and 2009. Couric's interview with then-Republican vice presidential candidate Sarah Palin in 2008 was a memorable moment in the campaign after Palin couldn't or wouldn't answer Couric's question about books or magazines she regularly read.

Even with those high points, broadcast news economics had changed markedly since she signed on with CBS and her reported $15 million a year salary became increasingly hard to justify for a third-place telecast. Fager, the "60 Minutes" executive producer, was installed as CBS News chairman two months ago and new executives frequently like to put their own stamp on newscasts.

Rome Hartman, Couric's first executive producer at the "CBS Evening News," said that while Couric's tenure clearly didn't work out as well as CBS hoped, "I don't think it's right to think of it as, or call it, a failure."

For the first time in many years, a network tried to increase the number of viewers watching the evening news instead of trying to steal a bigger slice out of an ever-shrinking pie, said Hartman, editor of "BBC World News America."

"There are people who love Katie and those who don't love her and that was a factor," he said. "But it was the overall dynamics. There was a rock that we couldn't move and I don't think it would have mattered who we would have put in there."

Although Couric will leave the evening news, she might not leave CBS. The CBS Corp. is a powerful force in the syndication business as owners of "Dr. Phil" and "Judge Judy," and the upcoming departure in May of Oprah Winfrey will leave a huge void in the talk show marketplace. Through CBS-owned stations, the company could give a big head start to a Couric show. Due to the sales calendar, such a show would not likely begin until fall 2012.

A syndication deal with CBS is seen as the only possibility that Couric would continue as evening news anchor on a temporary basis past June, if she were to agree to stay during an extended search for her successor.

Other chief contenders for Couric's services are NBC and Telepictures. NBC is her old home, but is not considered a big player in the talk show business. It tried and failed to launch a show for Jane Pauley, one of Couric's predecessors on "Today." Telepictures is bigger in the marketplace, producing "Ellen" and a new show with Anderson Cooper debuting in the fall, both of which could take potential time slots away from Couric.

Each of the companies has related news divisions where Couric could have some visibility before starting a talk show _ at CBS, NBC or CNN, through Telepictures.

The personality that Couric could be expected to readily display on the talk show circuit could be seen last week in a video posted by aol.com. Couric, who has actively encouraged Americans to get colonoscopies since her husband died of colon cancer, took a humorous look at undergoing her own test. Her doctor jokingly noted that he had found a Batman doll while looking at Couric's internal organs.