Shares in UK supermarkets Sainsbury’s and Morrisons were both up after news of merger between Dutch-based Ahold and Belgian Delhaize.

In the deal announced today, Ahold will hold a 61% stake in the merged entity headed by Ahold Chief Executive Dick Boer. The merged company will have 54.1 billion euros in sales, more than 6,500 stores worldwide and complementary operations in the United States and Benelux, making it the biggest supermarket merger in a decade.

Ahold, known in Europe as owning the Albert Heijn chain of supermarkets in the Netherlands, is also operator of Stop&Shop and Giant stores in the United States, while Delhaize owns the Food Lion and Hannaford chains.

After news of this deal, Sainsbury’s shares were up 2.4%, and Morrisons up 2.1% Sainsbury’s shares were also boosted by Societe Generale raising its rating on the stock to “buy” from “hold”.