Discount grocer Aldi continues to be the fastest growing food retailer in terms of sales while supermarket Sainsbury‘s outpaced its big four rivals as the only grocer to grow market share in May, new data has revealed.

Aldi reported a 25.2 per cent increase in sales over the four weeks ended May 25th 2013, posting a market share of 2.9 per cent from 2.4 per cent, according to new figures from Nielsen.

Sainsbury‘s saw its share of the grocery market rise 0.1 per cent to 16.1 per cent as sales leapt 4.9 per cent over the period and such strong results follow news that the chain‘s CEO Justin King saw his pay package leap more than 20 per cent to £4.3 million.

May‘s early Bank Holiday and improving weather towards the end of the month helped boost overall sales as Marks and Spencer, Lidl and Iceland all saw market share increases to 3.6 per cent, 2.1 per cent and two per cent respectively.

Mike Watkins, Nielsen‘s UK Head of Retailer and Business Insight, explained: “The recent four week reporting period was a tale of two halves.

“The first two weeks and the better weather saw strong growths, while the middle of May saw slowing growths compared to the same period in 2012 with its warm weather.

“Spend on offer fell to 33 per cent of sales, and while this is still high, retailers are using multiple tactics to encourage shopper loyalty including couponing and vouchering, everyday low price and loyalty card initiatives, as well as in store promotions.”

Upmarket grocer Waitrose also reported a boost, growing its market share 0.3 per cent on the same period last year to 4.5 per cent, though the big four struggled to maintain a stronghold.

Supermarket giant Tesco, which yesterday reported a decline in like-for-like sales across its international operations, saw its share dip 0.2 per cent to 28.3 per cent though sales increased 3.3 per cent on the same period in 2012.

Asda and Morrisons also posted declines in share, with the former reporting a 0.4 per cent fall to 16 per cent while the latter‘s share now stands at 11 per cent, down 0.3 per cent on last year.

“Sainsbury‘s continues to lead the top four supermarkets in terms of sales growths so their market share has increased over the last 12 weeks,” Watkins noted.

“Waitrose also grew share, however, the fastest growing food retailer continues to be Aldi with a 25 per cent increase in sales.

“With continued high levels of advertising, Aldi is one of the few retailers consistently able to attract significantly more new shoppers.”