The founding families of Carrefour have formalised their divorce from management of Europe's biggest retailer, in a move that could weaken the company's defence against outside bidders.

The refusal of three long-term owners of Carrefour shares - the Badin, Defforey and Fournier families, who control 3% of the shares - to renew the pact with the group's biggest shareholder the Halley family, will be a blow to Daniel Bernard, chairman of Carrefour. The three can now sell their stakes or launch a takeover bid without consultation with other shareholders.