On Friday, Amazon and Whole Foods announced that they entered into a definitive merger agreement for the tech giant to acquire the organic grocer for $42 a share.
After the acquisition, Mackey's 0.31% sliver of Whole Foods will be worth $41.2 million, as he currently owns 980,000 company shares.
On Thursday, before the deal was revealed, shares of Whole Foods closed at $33.06, leaving Mackey with $32.4 million, nearly $10 million less.
Whole Foods declined to comment for this story.
After the merger was announced, Whole Foods' competitors including Walmart Stores Inc. (WMT) , Kroger Co. (KR) , Costco Wholesale Corp. (COST) and Target Corp. (TGT) saw their stocks plummet as this means Amazon, the force upending tech and retail alike, just got a lot stronger with a fleet of some 456 stores.
"Implications ripple far beyond the food segment, where dominant players like Walmart, Kroger, Costco and Target now have to look over their shoulders at the Amazon train coming down the tracks," Moody's Investors Service analyst Charlie O'Shea said.
Shares of Whole Foods rose 27.05%, hitting $42 a share late this morning. Amazon stock inched up 2.53% to $987.60 a share.