Atlanta is adding another fast-food company to its ownership portfolio.

Chattanooga-based Krystal announced Thursday that it had been purchased by Argonne Capital Group, an Atlanta private equity firm that owns hundreds of IHOP, Applebee's and Stevi B's Pizza locations.

The purchase price was not disclosed.

“Finding the right owner, one that will continue to uphold the qualities of the Krystal brand that have made it a Southern icon, has been an important part of this transition,” Krystal President and CEO Fred Exum said in a release. “Argonne recognizes the strength of the brand and provides a foundation for the Krystal family of employees and franchisees to continue its expansion by serving our loyal customers.”

Don't look for the 80-year-old company to relocate its headquarters here, however. Krystal management said it is staying put in Tennessee.

The company, known for its small bite-sized burgers, was placed on the market last summer. It has more than 6,000 employees and owns and franchises 360 restaurants in 11 southern states.

Argonne was founded in 2003 and focuses on acquiring businesses in the real estate, restaurant and retail industries, the company said. Argonne was attracted to Krystal because of its strong business and leadership in its category.

“We have watched with great interest as Krystal has continued to develop quality products, offer outstanding customer service and maintain brand dominance through the recession,” Argonne President and founder Michael Klump said.

Atlanta is the home of several large fast-food companies, including Chick-fil-A, Arby’s, Church’s Chicken and Popeyes Louisiana Kitchen.