ASDA has overtaken Sainsbury’s to become UK’s second-biggest supermarket group behind Tesco

Kantar said wider year-on-year sales over the 12 weeks to March 24 lagged to 1.4 per cent - the slowest rate since March last year - in part due to the late Easter and Mother’s Day falling outside the reported period.

Sainsbury’s sales fell 1.8% over the quarter, cutting its market share to 15.3% from 15.8% in the same period last year.

Asda had a market share of 15.4% to edge it up as its sales climbed 0.1%, while Tesco grew by 0.5% to achieve a market share of 27.4%.

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However, Sainsbury’s remained the biggest seller of food and drink out of the two jockeying retailers as its figures do not include its Argos arm.

Sainsbury’s agreed £7.3 billion takeover of Asda is currently being considered by the Competition and Markets Authority, which gave an initial view last month that the deal should be blocked in the absence of the sale of a large number of stores, or even one of the brands.

A final report is due by April 30.

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Aldi saw its sales increase by 10.6%, helping it to a new record high market share of 8%, as 13 million households visited at least once over the last quarter, now more than those shopping at Morrisons.

Lidl was the second fastest-growing supermarket, with sales increasing faster than last month at 5.8% and market share growing by 0.3 percentage points to 5.6%.

Fraser McKevitt, head of retail and consumer insight at Kantar, 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.”