The network is about to re-sign the Emmy-winning talk show personality to continue hosting "Late Show With David Letterman" through the 2011-12 season, sources said. The agreement would mark a two-year extension of his current contract, set to expire in 2010.

The decision comes as NBC makes dramatic changes to its late-night lineup, moving top-rated host Jay Leno to 10 p.m. in the fall and installing Conan O'Brien behind the "Tonight Show" desk. O'Brien bested Letterman in the ratings during his first week on "Tonight," but the gap narrowed as the frame progressed.