The Large Stores and Food Chains Trade Index is a direct indication of trends in trade and employment in the Large Stores and Food Chains Sector in the Basque Country Regional Community. Two indices are calculated for this purpose; a "Sales Index" and an "Employed Personnel Index", desegregating the former according to the type of product sold: Food and Rest of Products.

Large Stores Trade is understood to be that which is carried out by retail trade companies in establishments whose sales area is equal to or greater than 2,500 m². A food chain is defined as a company with at least three premises in the Basque Country, including any large stores it may have, and more than 100 employees, engaged in retail sale in non-specialised stores, with food, beverages and tobacco predominating.