British supermarket group Asda, which has been losing market share, said its chairman, veteran retailer Stuart Rose, will assume the executive responsibilities of co-owner Mohsin Issa, who is stepping back from his leadership role.

The UK’s third largest grocer has underperformed rivals, including market leader Tesco and No. 2 Sainsbury’s, over the last year, with monthly data consistently showing it to be the industry laggard.

Data published on Wednesday from market researcher NIQ showed Asda’s sales fell 5.5% over the 12 weeks to September 7 year-on-year, and it lost 1.3 percentage points of market share over the year.

Last month, Rose, 75, who is a former CEO of Marks & Spencer and a former chairman of Ocado, told the Telegraph newspaper he was embarrassed by Asda’s performance.

Asda has been without a chief executive since Roger Burnley left abruptly in 2021.

While the search for a permanent CEO continues, it said Rose would work alongside Rob Hattrell, a partner at private equity firm TDR Capital, who was already a director on the supermarket group’s board.

Asda is owned by Issa and TDR Capital, while US giant Walmart, its previous owner, retains 10%.

“I have decided now is the right time for me to step back from my oversight role at Asda,” said Issa.