By Natalie DeCoste

WPP’s media agency GroupM has decided to end its relationship with Facebook and withdraw from its global media review.

WPP is a British multinational communication company specializing in advertising, public relations, technology, and commerce. One of WPP’s agencies is GroupM, the world’s leading media investment company responsible for more than $50B in annual media investment.

GroupM, specifically GroupM’s Mindshare, is Facebook’s incumbent ad-buying shop and has handled the bulk of Facebook’s global media planning and buying business. GroupM’s Mindshare has supported the business across various Facebook brands since 2014, but that relationship is coming to a close.

“We’re sorry that GroupM has decided to withdraw from the RFP [request for proposal] process; however, we look forward to continuing to partner with their talented team as we move forward with our review of global media capabilities,” a Facebook spokeswoman said on the matter.

While the move will likely bring an end to the majority of GroupM’s work with Facebook, the group will maintain its ties to Facebook and continue to assist the social media giant through the review process.

“While we will not be participating in the review, we look ahead to future opportunities building on the successful work we created together since 2014. We are proud of the work that our teams and people have done for Facebook and wish them the very best in their media selection process,” said a GroupM spokesperson.

The exact reason for the withdrawal is not known. Some reports suggest that Facebook may be asking for new contractual terms around liability in the ad buying process. Contracts between agencies and marketers often require the agencies to take on certain levels of liability or risk if an issue arises around the ad-buying process, putting GroupM on a bigger hook for anything that may go wrong. Advertisers also often include terms around the right to audit an agency group.

The role GroupM played in Facebook’s ad business is significant. Facebook’s media mandate includes media planning and buying across the company’s entire business, including Instagram, Facebook, WhatsApp, and Messenger. The scope of the ad-buying business reportedly covers ad spending up to $1 billion.

The billion-dollar business is highly sought after, meaning that many rival advertising firms are now vying for GroupM’s place. Dentsu Inc., Havas Group, and Publicis Groupe SA are reportedly all still competing for the account.

The move comes amidst the shift to the more complex digital marketing world. Digital marketing involves complex systems, outside vendors, and less transparency than traditional media buying. The complexity of the digital marketing world is likely linked to the liability issue in the two companies’ contract as digital marketing raises increased concerns over a data privacy breach or ad fraud.

Even as GroupM closes the chapter of its relationship with Facebook, the company still has many other high-profile accounts on its books. The agency boasts high-profile clients such as Coca-Cola Co., Unilever PLC, Bayer AG, and Chanel, who are likely to keep the agency busy.