Wal-Mart reported to have earmarked two possible candidates to succeed CEO Mike Duke (above)

Wal-Mart reported to have earmarked two possible candidates to succeed CEO Mike Duke (above)

In a week dominated (at least in the mind of one of the just-food editorial team) by the retirement of Sir Alex Ferguson from Manchester United, there were questions and rumours about the future of two senior food retail CEOs - and confirmation that a third did plan to step down.

Last week, Bloomberg reported Wal-Mart's board had earmarked two possible internal candidates to succeed CEO Mike Duke.

Bill Simon, the head of Wal-Mart's US arm and Doug McMillon, who heads up its international operations, have been identified as potential replacements, Bloomberg said. An unnamed source said Duke is not expected to leave immediately but added the world's largest retailer could name his successor in the coming months. Wal-Mart could not be reached for immediate comment but rumours it could soon announce only its fifth CEO in its history will cause industry watchers to wonder who will take the helm as the company battles the rise of dollar stores in the US and Amazon worldwide.

In February, Wal-Mart issued a cautious forecast for its first quarter in the US (the results of which we will hear on Thursday) but some industry watchers believe it has had success in luring shoppers away from some of the country's traditional supermarket chains.

Belgium-based Delhaize Group owns US supermarket chains like Food Lion and Hannaford and has had some problems Stateside in recent years. In January last year, it announced plans to close over 100 stores in the US and withdraw its Bloom banner from the market. Underlying margins and same-store sales in the US fell in 2012; in response, Delhaize has shaken up its US management team and announced job cuts in the country. However, Delhaize has also invested in price, repositioned its Food Lion brand and expanded discount chain Bottom Dollar Food.

Last week, Delhaize said comparable-store sales in the US were up almost 2% in the first quarter and margins increased. Its moves to revitalise its US business, then, seem to be gaining some traction.

But Delhaize's first-quarter sales update was accompanied by news president and CEO Pierre-Olivier Beckers was stepping down. Beckers, who has spent 15 years as chief executive, said Delhaize was "moving in the right direction" after "a challenging few years". However, he said now was the right time for "a fresh pair of eyes" and some "new thinking" for the business.

In our On the move column, we analysed Beckers' time at Delhaize, which some analysts believe could now be set for some radical change.

In the UK, the chief executive of Sainsbury's, Justin King, faced fresh questions about his future. Sainsbury's, the UK's third-largest grocer, reported another solid set of annual results last week. King, who joined Sainsbury's in 2004, said the retailer had out-performed its rivals and set out his plans for the company in the coming year, including a step-up in investment in its convenience store network.

However, at a media conference after the results, King had to fend off renewed queries over his own future. There have been reports Sainsbury's has hired an executive search agency to find a replacement for King, although, on Wednesday, both he and Sainsbury's chairman David Tyler refused to confirm whether headhunters had been appointed.

"I've been very clear about my position and that this is a great company with fantastic future prospects. I see myself playing my part in that," King insisted. His comments may not satisfy those wanting a definitive answer; could King, in fact, become Sainsbury's chairman? But it seems, for now, the Sainsbury's boss and Sir Alex Ferguson admirer will remain in his post.