UK's No 2 and No 3 supermarkets to merge
Sainsbury's, formerly the second biggest supermarket, and Walmart-owned Asda, which held the third spot, said they plan to combine to overtake Tesco.
The deal would need approval from the competition authorities.
The supermarkets said the union, which would result in a group with lb51 billion (EUR58 billion) of sales, would cut costs for consumers.
Britain's traditional supermarkets have been suffering amid competition from discount stores such as Lidl and Aldi as well as online giant Amazon.
