Asda’s grocery market share has overtaken suitor Sainsbury’s for the first time since 2015, according to the latest data.

The Kantar grocery market share figures also showed more households shopped at Aldi than at Morrisons.

Asda’s sales rose 0.1% in the 12 weeks to March 24, when it achieved a market share of 15.4%.

This was marginally ahead of Sainsbury’s share of 15.3%. Sainsbury’s, which plans a £13bn merger with Asda, experienced a sales fall of 1.8%.

Asda drew “a greater number of affluent households and shoppers making more regular trips”, according to Kantar.

However, Kantar head of retail and consumer insight Fraser McKevitt said: “Despite being overtaken by Asda in main store sales, Sainsbury’s remains the biggest seller of food and drink out of the two retailers and these figures do not include Argos.”

Sainsbury’s said: “The headline figure on market share is distorted by the fact that Argos sales are excluded by Kantar. Since 2016, Sainsbury’s has streamlined its general merchandise ranges in favour of Argos general merchandise as it continues the successful integration.”

Aldi’s sales climbed by 10.6% in the period when the retailer again notched up a record market share of 8%.

McKevitt expected further growth. He said: “London holds potential for Aldi, as both its fastest-growing region and where its market share is currently lowest, going some way to explain the recently announced trial of the smaller Aldi Local format in the capital.”

Morrisons drew an additional 40,000 shoppers over the past year, but sales slipped 0.1% as shoppers picked up fewer items on each trip.

Grocery sales overall rose 1.4% in the period. This year’s late Easter, and Mother’s Day falling outside the 12 weeks, contributed to the market growing at its slowest rate since March 2018 and reduced overall growth by 0.5 percentage points.

After Aldi, Lidl was the second-fastest-growing supermarket. Its sales advanced 5.8% and its market share rose 0.3 percentage points to 5.6%.

Tesco’s sales increased 0.5% to give it a market share of 27.4%, 0.2 percentage points lower than a year ago.

Waitrose’s sales rose 1.3%, its best showing since August 2018. The retailer cut promotions and increased full-price sales.