Carrefour shares tumbled on Wednesday morning, falling as much as 5% in early trades.
That on news that luxury goods billionaire Bernard Arnault is selling his stake.
Arnault - named the world's richest man by Forbes magazine in May - is head of luxury group LVMH.
He first invested in Carrefour 14 years ago.
But Wednesday saw him raise around $854 million selling his remaining stake.
Carrefour has been through several transformations in recent years, with investors benefiting as it sold off businesses.
Arnault was one of its top three shareholders.
Back in January he supported chief executive Alexandre Bompard in talks over a $20 billion takeover bid by Canadian retail chain Couche-Tard.
That deal eventually collapsed in the face of French government opposition.
Bompard now says Carrefour is viable on its own, and has been given an extended term to drive turnaround efforts.