Diane Sawyer Exits as Anchor of ABC World News

Diane Sawyer gave up her anchor seat on ABC World News.

The 68-year-old acclaimed journalist passed the torch onto David Muir after anchoring the program since Dec. 2009, but for some, this came as a surprise. While it was no secret that Sawyer was leaving the show this week, it was never announced that Wednesday would be her last day until she tweeted earlier that day.

"It has been wonderful to be the home port for the brave and brilliant forces of ABC News around the world and to feel every single night that you and I were in a conversation about the day together," she said in her sign off.

As for Sawyer's next moves, she assured viewers, "I am not slowing down, but gearing up in a new way, already at work on some of the stories that take you into the real lives around us, the ones we rarely get to see."

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She concluded, "So one last time, it is good to know you were watching tonight … I thank you and I'll see you right back here at ABC News very soon."

Sawyer leaves the program with high ratings. In her final week, the show ranked No. 1 in the news demo and, according to People, "won back-to-back sweeps among adults 25-54 for the first time in seven years."

Muir will take over ABC News on Sept. 2.