Big changes are coming to ABC's "World News."

Dianne Sawyer is hanging up her duties as lead anchor on ABC's "World News" at the end of August. Sawyer has been the lead anchor of "World News" for the last 5 years.

Sawyer will be staying with ABC to work in more of an investigative and enterprise reporting role according to ABC News.

ABC News chief James Goldston wrote, "Dianne decided that now is the moment to concentrate full time on tackling big issues in new ways. She will create innovative television specials and events, and, of course, continue to conduct the biggest interviews with the most important and extraordinary people in the world.”

Another source at ABC said the choice for Sawyer to step away from the anchor desk was "entirely her decision."

Replacing Sawyer as lead anchor will be David Muir. Muir is currently serving as the weekend anchor for ABC News and is also the co-anchor of ABC's newsmagazine "20/20."

Muir will take over on September, 2nd after Sawyer's departure, and will frequently fill in for Sawyer throughout the summer as she takes time off according to sources at ABC.

New York Daily News contributed to this story.