The biggest supermarket chain in the U.S. is Walmart. As of 2021, Walmart operates over 11,500 stores under 56 differentbanners in the U.S. alone, including Walmart Supercenter, Walmart Neighborhood Market, Sam's Club, and others. It is estimated that Walmart has a 20% share of the U.S. grocery market. Walmart's closest competitor in termsbrand names, including Walmart Supercenters, Neighborhood Markets, and Sam's Club stores. In terms of revenue, Walmart is the largest company in the world, generating over $500 billion in annual revenue.