Title: List of supermarket chains in the United Kingdom
Content:  This is a list of supermarket chains in the United Kingdom. Grocery sales in the UK are dominated by Tesco, Asda, Sainsbury's and Morrisons. These, dubbed the "big four", had a combined market share of 73.2% of the UK grocery market in the 12 weeks ending 4 January 2015, a decline from 74.1% in 2007. Discounters Aldi and Lidl have seen a combined rise in market share from 4.8% to 8.3% over that time, while upscale grocer Waitrose's share rose from 3.9% to 5.1%. As of KANTAR data published on 24 March 2019, the market share is dominated by Tesco, with Asda being second, Sainsbury's third and Morrisons fourth. The London Co-operative Society opened Britain's first fully self-service store in January 1948 in Manor Park, London. Premier Supermarkets, a subsidiary of Express Dairies, opened the UK's first supermarket in Streatham, South London in 1951. In early 2017, Tesco announced a deal to merge with Booker, the UK's largest wholesale food retailer, while Aldi became the 5th biggest supermarket.
Title: List of supermarket chains
Content:  As of September 2020, this is a list of supermarket chains, past and present, which operate or have branches in more than one country, whether under the parent corporation's name or another name. For supermarkets that are only in one country, see the breakdown by continent at the bottom of this page. Numbers are provided as the largest reported, and are largely inaccurate.
Title: Sainsbury's
Content:  J Sainsbury plc, trading as Sainsbury's, is the second largest chain of supermarkets in the United Kingdom, with a 16.0% share of the supermarket sector. Founded in 1869 by John James Sainsbury with a shop in Drury Lane, London, the company became the largest retailer of groceries in 1922. In 1995, Tesco overtook Sainsbury's to become the market leader, which has since been ranked second or third, being overtaken by Asda from 2003 to 2014, and again in 2019. In 2018, a planned merger with Asda was blocked by the Competition and Markets Authority over concerns of increased prices for consumers. The holding company, J Sainsbury plc, is split into three divisions: Sainsbury's Supermarkets Ltd (including convenience shops), Sainsbury's Bank, and Argos. As of 2021, the largest overall shareholder is the sovereign wealth fund of Qatar, the Qatar Investment Authority, which holds 14.99% of the company. It is listed on the London Stock Exchange and is a constituent of the FTSE 100 Index.
Title: List of supermarket chains in the United Kingdom
Content:  These supermarkets are either no longer trading, have been renamed, or have been taken over and rebranded.
Title: List of hypermarkets
Content: Asda (Walmart) ; Marks and Spencer ; Sainsbury's ; Tesco Extra Defunct: ; Carrefour – first Carrefour store opened in the 1970s; UK business was sold to Gateway/Somerfield in 1990 and later was sold to Asda ; Sainsbury's Savacentre – joint ventures between Sainsbury's and BHS, later rebranded Sainsbury's Superstores The largest chains in the UK are Tesco, Asda and Sainsbury's, which all operate hypermarkets in the country.  
Title: Aldi
Content:  In the United Kingdom, Aldi has won Supermarket of the Year two years in a row (2012/13), and in 2013, Aldi won the Grocer of the Year Award. In February 2015, Aldi narrowly lost to Waitrose for the title of Supermarket of the Year 2015. In April 2015, Aldi overtook Waitrose to become the United Kingdom's sixth-largest supermarket chain. In February 2017, Aldi overtook Co-op to become the United Kingdom's fifth largest supermarket chain. In May 2017, Aldi lost out to Marks & Spencer for the title of Supermarket of the Year 2017 (published by the magazine Which?). According to research firm Kantar Worldpanel, nearly two-thirds of households within the UK now visit 
Title: List of supermarket chains in Europe
Content: Carrefour 
Title: List of supermarket chains in Ukraine
Content:  This is a list of supermarket chains in Ukraine.
Title: List of supermarket chains in the United States
Content:  This is a list of supermarket companies in the United States of America and the names of supermarkets which are owned or franchised by these companies. For supermarkets worldwide, see List of supermarkets.
Title: List of supermarket chains in Africa
Content: Grande Mundo 

Question: who is the largest supermarket chain in the uk?
Answer: Aldi.
Tesco.