The CEO of Whole Foods is calling out activist investor Jana Partners, tagging them "greedy bastards" who are only interested in making money from a forced sale of the struggling grocer.
"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.
Earlier this year, Jana disclosed a stake in Texas-based Whole Foods and has since said it is determined to change the company's board. The firm has been telling Whole Foods to either overhaul its operations or look for potential buyers.
Whole Foods declined to comment to CNBC on the story, and a representative from Jana didn't immediately respond to an email.
Mackey's harsh criticism of Jana comes at a time when his company's same-store sales have fallen for seven consecutive quarters.
Grocery is proving to be a more competitive industry to be in today, with more nontraditional players trying to swoop in and steal market share. Amazon, for example, continues to roll out its AmazonFresh business. And now there's Lidl, a German grocer, opening its first stores in the U.S. Thursday.
"We need to evolve," the Whole Foods CEO told the Texas-based publication. "We need to get better, and we're doing that. But these guys just want to sell us, because they think they can make forty or fifty percent in a short period of time."
In his interview with TexasMonthly, Mackey went on to criticize other "greedy" business leaders in America today.
"There's a narrative about business in America that says, 'Business sucks,' " Mackey said. "It's the idea that business is about a bunch of greedy bastards running around exploiting people, screwing their customers, taking advantage of their employees, dumping their toxic waste in the environment, acting like sociopaths."
Last month, Whole Foods finally did decide to overhaul its board, appointing five new members and replacing the grocer's chairman.
The new appointees come with deep backgrounds in both retail in and in corporate turnarounds, while Whole Foods' new CFO, Keith Manbeck, brings much-needed e-commerce experience.
Watch: Jana concerned new board members lack grocery experience