JAB Holding Co., the investment firm backed by Austria’s billionaire Reimann family, is expanding its U.S. food empire.

The firm’s Panera Bread business has agreed to acquire the Au Bon Pain bakery chain, adding about 200 U.S. cafes -- and another 100 abroad -- to a sprawling portfolio that includes coffee, doughnuts and bagels. Terms of the transaction, which unites restaurant brands that were part of the same company until the late 1990s, weren’t disclosed.

The purchase comes a few months after JAB bought Panera in a $7.2 billion takeover, thrusting the firm into the fast-casual restaurant market. That acquisition brought more than 2,000 cafes that are popular with the lunch crowd. Au Bon Pain will bring restaurants that also emphasize bread and pastries, with locations in places like hospitals, colleges and train stations.

“They want to be dominant in coffee and restaurants that sell coffee,” said Michael Halen, an analyst at Bloomberg Intelligence. “They’ve been very aggressive over the last few years.”

The move disappointed investors in Dunkin’ Brands Group Inc. (Nasdaq: DNKN), which has been cited as a potential takeover target for JAB. The investment firm has previously scooped up Keurig Green Mountain, Krispy Kreme, Caribou Coffee, the Einstein Noah Restaurant Group, Peet’s Coffee & Tea and Stumptown Coffee Roasters -- a buying frenzy that has jolted the food industry.

Adding Dunkin’ Donuts would give JAB a hard-to-match assortment of coffee and breakfast brands -- bringing heavier competition to Starbucks Corp. (Nasdaq: SBUX), the world’s largest chain of cafes. With that possibility looking more remote,

The latest deal also reconnects Panera CEO Ron Shaich with his old business. He and the late Louis Kane started Au Bon Pain in 1981. The company went on to acquire Saint Louis Bread Co., which was later renamed Panera. The Au Bon Pain brand was sold off in 1999.

The reunion will serve as a swan song for Shaich, who is stepping down as Panera’s CEO on Jan. 1 -- a move the company announced shortly after news of the deal hit. His deputy, Blaine Hurst, will take the reins, with Shaich remaining chairman.

Au Bon Pain, meanwhile, has struggled to maintain growth. In 2016, the Boston-based chain’s sales slipped 3.2 percent to about $352 million, according to Technomic, a restaurant research firm.

JAB began building its caffeine-focused empire with the 2012 purchase of a stake in Amsterdam-based D.E Master Blenders 1753 NV, the maker of Senseo and Douwe Egberts brands. In the U.S., JAB has developed a portfolio of co-branded restaurants called Coffee & Bagels, which offer Caribou java and Einstein Bros. bagels.

Four Reimann siblings -- Renate Reimann-Haas, Matthias Reimann-Andersen, Stefan Reimann-Andersen and Wolfgang Reimann -- have a combined net worth of $11.6 billion, according to the Bloomberg Billionaires Index.

JAB also controls cosmetics maker Coty Inc., which announced an agreement this week to license Burberry Group Plc’s beauty brands.

It’s too early to say if the Au Bon Pain locations will be rebranded, Shaich said in an interview. One of the first orders of business will be investing in technology at the chain. Panera has been a leader in digital-ordering features, and expanding that to Au Bon Pain should help boost sales, he said.

While he plans to step back from the daily grind of running Panera, Shaich remains an investor in the company and will be involved as it completes the takeover of Au Bon Pain. The deal was attractive to Panera in large part because of the real estate assets the company is acquiring, he said.

“The reason we’re doing it is not about me and closing the circle,” he said. “The reason we’re doing it is because these are powerful assets -- this is a strategic growth play.”