Ending a spate of media speculation rivaled only by rumors over some pop stars' impending marriage or divorce, Katie Couric announced on NBC's Today show today that she will be leaving to become the anchor of the CBS Evening News. On an edition of Today that marked Couric's 15th anniversary with the show, she told the audience that "after listening to my heart and my gut, two things that have served me pretty well in the past" she had decided to leave at the end of May. "Although it may be terrifying to get out of your comfort zone, it's also very exciting to start a new chapter in your life," she said. At CBS, she is expected to replace interim anchor Bob Schieffer in late August or early September. Advertisers, analysts, and TV columnists, who had engaged in a flurry of will-she-or-won't-she gossip leading up to today's announcement, went into wait-and-see mode. Susan Nathan, a senior exec at the Universal McCann ad agency, told Bloomberg News: "It's probably time for her to do something else that's more challenging." CNN/Money commentator Paul R. LaMonica wrote: "It's wrong to assume that Today ratings will plummet and ad revenue will dramatically decrease for NBC and its parent company General Electric. Today existed before Katie Couric joined it. (Remember Jane Pauley?) It will go on without her." Media guru Jack Meyers told the New York Post: ""I wouldn't expect to see a sudden drop-off, but it certainly tosses the morning up in the air." Many analysts also expressed doubts that Couric would boost ratings for the CBS Evening News. Daily Variety pointed out that CBS had previously failed in its efforts to transfer Bryant Gumbel's success on Today to similar success on The Early Show. Paul McLeary, politics and media reporter for the online edition of the Columbia Journalism Review, "Let's face it: The news is the news, whether it's Brian Williams, Bob Schieffer or Katie Couric reading from the teleprompter. ... You could put just about any charismatic talking head with some modicum of news sense in the chair and let them follow the teleprompter's instructions, and people would tune in."