John Mackey, the chief executive of Whole Foods, attacked one of the health-focused US supermarket chain’s biggest investors, Jana Partners as “greedy bastards” on Thursday.

“They’re putting a bunch of propaganda out there, trying to destroy my reputation and the reputation of Whole Foods, because it’s in their self-interest to do so,” Mackey said in an interview with TexasMonthly.

The New York-based hedge fund Jana Partners announced in April that it had acquired a 9 percent stake in Whole Foods and would push the upmarket grocer to overhaul its business or start looking for potential buyers.

Whole Foods was founded in Texas in the 1980s and expanded its operations through more than a dozen acquisitions to become the country’s biggest premium grocer.

However, it has been struggling to compete with other supermarket chains for the past two years.

Same-store sales have fallen for seven consecutive quarters, however the grocer insists that it has a turnaround plan and will proceed with “a greater sense of urgency.”

The company’s chief financial officer, chairman and several board members were replaced last month as part of a restructuring push.

Whole Foods’ new CFO, Keith Manbeck, boasts significant e-commerce experience in an effort to bolster the grocer’s online presence.

The reforms to the Whole Food’s strategy and its board won’t be enough for Jana Partners to change its tune, Mackey insisted.

“These people [Jana Partners], they just want to sell Whole Foods Market and make hundreds of millions of dollars, and they have to know that I’m going to resist that,” said Mackey. “That’s my baby. I’m going to protect my kid, and they’ve got to knock Daddy out if they want to take it over.”