A deal is brewing to bring Panera Bread and Boston-based Au Bon Pain together after two decades, and it is steaming investors of Dunkin' Donuts.

JAB Holding Co., the European investment firm that announced in April it was buying Panera for $7.16B, is hungry for another bakery. Panera has agreed to take over the 300-café Au Bon Pain chain. Terms of the deal were not disclosed, but it is expected to close in Q4, Bloomberg reports.

Investors of Canton, Massachusetts-based Dunkin’ Brands Group are said to be disappointed, as the coffee-and-doughnut conglomerate was seen as a potential acquisition for JAB. JAB bought Krispy Kreme Doughnuts Inc. in 2016 for $1.35B and Keurig Green Mountain Inc. for nearly $14B. While a Dunkin' acquisition could give JAB a sizable portfolio of breakfast brands to compete with Starbucks, the possibility of such a deal is now seen as slim. Dunkin’ shares fell 4.7% at one point this morning to $55.75, the biggest intraday drop the company had seen in a year.

Panera founder, Chairman and CEO Ron Shaich announced he will step down as CEO on Jan. 1, but remain chairman of the board of directors and continue to work with the company on strategy and acquisitions. Panera President Blaine Hurst will take over as CEO.

Shaich and his business partner, Louis Kane, who died in 2000, started Au Bon Pain in Boston in 1981. The company grew and eventually acquired St. Louis Bread Co. in 1993 and took the company national under the name Panera. They grew Panera and Au Bon Pain as distinct brands before selling off the latter in 1999.

While Shaich said it is too early to determine if the Au Bon Pain name will go away, he said expanding Panera’s digital ordering technology will expand to the newly acquired company to help boost sales.