Watch out Walmart and Amazon. Dutch grocer Ahold is creating a giant by buying its Belgian rival Delhaize for 25 billion euros ($28 billion). Besides creating a major player in Europe, the deal will merge four supermarket chains on the U.S. east coast: Ahold's Stop & Shop and Giant stores and Delhaize's Food Lion and Hannaford markets. The companies say they will lower operating and purchasing costs and expand the reach of Ahold's online grocery store Peapod.