Austin, TX— Whole Foods Market, based here, is changing its leadership structure. The upscale grocer has named John Mackey, its founder, as sole CEO, ending a six-year arrangement where he shared the helm with longtime Whole Foods Market executive Walter Robb.

This news comes after the company reported a 2.6 percent decline in comparable store sales in its most recent quarter, its first annual drop since 2009. According to reports, lower commodity prices and competition from both mass market grocery stores and upstarts like Blue Apron or Amazon Fresh have led the Board to streamline its leadership structure.

“Under Walter’s leadership, Whole Foods Market has grown from 12 to 464 stores in three countries. He has been instrumental in accelerating investment in our digital strategy and technology transformation to meet the ever-changing retail landscape,” said Dr. John Elstrott, Chairman of Whole Foods Market’s Board of Directors, in a press release.

Mackey also expressed gratitude for Robb’s leadership. “His incredible passion for retail and sense of the customer makes him the most extraordinary retailer I’ve had the privilege to work with.” he stated in the company’s press release. “His genuine love for our mission and our Team Members truly reflects what it means to be a conscious leader.”

Robb will remain on the company’s Board of Directors and continue to serve as Chairman for both Whole Kids Foundation and Whole Cities Foundation.  He will officially step down as co-CEO  at the end of the year.