Aldi and Lidl double market share in three years
Discount supermarkets Aldi and Lidl have seen their joint share of the groceries market double to 10% in just three years, industry figures show.
Analysts Kantar Worldpanel said Aldi's market share was 5.6% in the 12 weeks to 8 November, while Lidl's was 4.4%.
Sainsbury's was the only one of the "big four" supermarket chains to increase sales and market share.
As a result, Kantar said Sainsbury's had overtaken Asda to become the second-largest UK supermarket chain.
Tesco remains the UK's largest supermarket with a 27.9% market share, while Sainsbury's has 16.6%, with Asda on 16.4%.
Asda's sales fell 3.5% in the latest quarter from a year earlier, more than any of its main rivals.
The figures come ahead of the release of Asda's third-quarter results. Asda chief executive Andy Clarke had described the 4.7% fall in the supermarket's sales in the previous quarter as the firm's "nadir".
UK supermarkets' share of grocery market
- Tesco 27.9%
- Sainsbury's 16.6%
- Asda 16.4%
- Morrisons 10.8%
- The Co-operative 6.3%
- Aldi 5.6%
- Waitrose 5.2%
- Lidl 4.4%
Source: Kantar Worldpanel (12 weeks to 8 November 2015)
The discount chains have been gradually eating into the market share of the biggest supermarkets, and have provoked a fierce price battle among the top four chains.
The latest Kantor Worldpanel figures show Aldi's sales rose 16.5% in the latest quarter from a year earlier, while Lidl's increased by 19%.
In contrast, sales at Tesco, the UK's largest supermarket chain, fell 2.5% from a year earlier, while Morrisons dropped 1.7%.
Fraser McKevitt, head of retail and consumer insight at Kantar Worldpanel, said: "If you look back as recently as 2012 Aldi and Lidl only held a 5% share of the market, and it had previously taken them nine years to double their combined share from 2.5%.
"In the last 12 weeks, the two retailers have attracted another additional million shoppers compared with last year, while average spend per trip has increased by 4% to £18.85, which is 78p ahead of the total retailer average.
"The discounters show no sign of stopping and with plans to open hundreds of stores between them, they'll noticeably widen their reach to the British population."
Elsewhere, Waitrose and the Co-operative saw sales rise by 2.7% and 1.5% respectively.
The Co-operative's market share grew to 6.3% from 6.2% - its first year-on-year share gain since 2011, when the benefits of its acquisition of the Somerfield chain were still being felt.