United Airlines is conducting global media and digital agency reviews.
Wavemaker is the incumbent media agency and Wunderman is believed to handle digital work for the airline company.
United spent an estimated $31 million on measured media in the U.S. last year according to Kantar Media. Global spending was not available.
Campaign reported the news first and cited a Wavemaker spokesperson as confirming that the GroupM agency will participate in the review.
A client rep did not return a query seeking comment. Wunderman could not be immediately reached.