Diane Sawyer will be stepping down from her role as anchor of "World News" after five years and will be replaced by David Muir, ABC announced Wednesday.
In addition, George Stephanopoulos, co-host of "Good Morning America," has been appointed to the newly created position of head anchor for ABC News.
According to a note sent by ABC News President James Goldston to staff, Sawyer will continue to report for the network "for many years to come" but will focus on "devoting her boundless energy full time to a team which will create and commission original reporting, big ideas and interviews for all platforms."
"Diane decided that now is the moment to concentrate full time on tackling big issues in new ways," he said.
Under Sawyer, who followed Charles Gibson as "World News" anchor in 2009, the broadcast, which is No. 2 in the ratings overall, has nearly caught up to ratings leader "NBC Nightly News with Brian Williams," narrowing the overall gap to under a million viewers. In recent months, Sawyer has also edged out Williams in the all-important 25-to-54 demographic, winning May sweeps for the first time in seven years by a margin of 106,000 viewers in the age group.
But according to Goldston, Sawyer began to express interest in a new role to Disney/ABC Television Group co-president Ben Sherwood late last year.
Muir, who is the weekend anchor of "World News" and co-anchor of the news magazine "20/20," will take over the weekday broadcast on Sept. 2. He will continue to anchor "20/20" with Elizabeth Vargas.
In his new position, Stephanopoulos will be the lead anchor for live coverage of breaking news and other major events. He will also continue at both "This Week" and the top-rated "Good Morning America."
The division of labor between Muir and Stephanopoulos is a somewhat unusual arrangement for network news, one seemingly designed to acknowledge Stephanopoulos' leading role in the news division without disrupting the successful formula in place at "Good Morning America."