Coca-Cola Marketing Executive Clark to Leave for DDB

Senior Coca-Cola Co. marketing executive Wendy Clark is leaving the beverage giant to head advertising agency DDB Worldwide’s North American business.

The high-profile departure comes at a critical juncture for Atlanta-based Coke, which is struggling to jump-start growth after missing targets in each of the last two years because of flagging soda consumption in the U.S. and elsewhere.

The maker of Coke, Sprite and Fanta plans to name a replacement shortly for Ms. Clark, who has been North American marketing chief since June 2014. The 44-year-old executive also helped steer global marketing after joining Coke in 2008 from AT&T Inc.

New York-based DDB said Ms. Clark’s appointment is effective in January. Mark O’Brien, the current North American chief executive, will assume a new role as executive vice president at DDB’s parent company, Omnicom Group.

Ms. Clark faces a tough assignment. Traditional creative agencies like DDB are trying to keep up with the rise of digital advertising as media and technology companies ramp up the services they offer directly to marketers. DDB’s clients include McDonald’s and State Farm.

Ms. Clark took a leave of absence in January to advise Hillary Clinton on her presidential campaign but returned to Coke in early April. One of her successor’s biggest challenges will be to reverse plunging sales of diet soda as growing numbers of Americans avoid artificial sweeteners over health concerns.

While Coke tried to keep Ms. Clark, the company’s time frame for promotions was too slow, according to a person close to the executive. Ms. Clark was eager to find a CEO role, according to this person, adding that Ms. Clark plans to split her time between New York and Atlanta.

Although she was seen as a rising star at Coke, Ms. Clark had no clear path to becoming chief marketing officer soon after company veteran Marcos de Quinto became CMO in January. Mr. Quinto replaced Joe Tripodi, who had been a big supporter of Ms. Clark. Mr. Quinto is expected to replace or tweak Coke’s “Open Happiness” global marketing campaign that was launched in 2009.

At the same time, Sandy Douglas, Coke’s North American chief, isn’t expected to retire from the company for at least another two years. Ms. Clark was considered a potential successor but Hendrik Steckhan, the 53-year-old head of North American noncarbonated beverages, is viewed by many as the most likely candidate to eventually replace Mr. Douglas.

DDB Worldwide Chief Executive Chuck Brymer praised Ms. Clark on Wednesday as a “game-changer” and “a magnet for talent.” The North American business is “in excellent health” thanks to Mr. O’Brien’s efforts, he added.

In an accompanying statement, Ms. Clark said it was a “privilege” working at Coke and that she is “excited” about joining DDB.

In a memo to Coke employees, Mr. Douglas, Coke’s North American chief, praised Ms. Clark for helping the company expand in social and digital media. He also credited her for helping with the global rollout of the popular “Share a Coke” marketing campaign in recent years and World Cup soccer advertising efforts last year.

Mr. Douglas added that Ms. Clark had built a “talented team and a deep bench” of marketers in North America. Senior marketing executives include Ivan Pollard, Emmanuel Seuge, Andrew McMillin, Kimberly Paige and Caren Pasquale Seckler.