Diane Sawyer is leaving Good Morning America. Sawyer bids farewell to her post at GMA as she prepares to join Brian Williams and Katie Couric in the nightly news race in January. Sawyer will be replacing Charlie Gibson on ABC’s World News, Media Bistro has learned.

“Diane’s presence will certainly be missed on Good Morning America. But we are fortunate that both Charlie and Diane will remain with their current broadcasts for the next four months,” ABC News president David Westin said in a statement Wednesday.

Sawyer has been with GMA since 1989.

The retiring Gibson, 66, has been the anchor of World News since May 2006, after replacing Elizabeth Vargas and Bob Woodruff following the death of longtime host Peter Jennings.

Charlie Gibson sent an email to his staff this morning, announcing his decision to retire after more than three decades in journalism. “It has not been an easy decision to make. This has been my professional home for almost 35 years. And I love this news department, and all who work in it, to the depths of my soul.”