Carrefour revealed yesterday (12 May) that billionaire investor Bernard Arnault is joining the retailer's supervisory board.

Carrefour said Arnault would replace Robert Halley on the board. Halley will become an honorary president while Amaury de Seze will become chairman of the supervisory board.

While the Halley family is a key stake-holder in Carrefour, it has recently loosened its grip on the company. In March the Halley family split its 13% stake into two separate holding companies -- Halley Participations SAS and Comet BV.

Meanwhile, over the last year Arnault and US property company Colony Capital have built up a 10.7% stake in the world's second largest retailer through their joint holding company Blue Capital.

Blue Capital now has three representatives in Carrefour's boardroom - Arnault, Nicolas Bazire and Colony Capital executive Sebastien Bazin.

Blue Capital has argued that the retailer should increase shareholder returns, possibly through the sale of some of the group's extensive property portfolio.

"The supervisory board is going to work with Jose Luis Duran, chairman of the management board, to extract all the potential within the group," de Seze said in a statement.

Following the news, shares in Carrefour increased on speculation that the group could be forced to increase shareholder returns, rising to to EUR46.26 (US$71.49) at time of press.

When contacted by just-food Carrefour declined to comment further on the appointment, but added that it has no plans to sell-off its property portfolio.

"Our strategy remains unchanged," Carrefour said.