Suncor Energy Inc. is a Canadian integrated energy company based in Calgary, Alberta. It specializes in production of synthetic crude from oil sands. In the 2020 Forbes Global 2000, Suncor Energy was ranked as the 48th-largest public company in the world. Suncor was created by Sun Oil in 1979 by the merger of its Canadian conventional and heavy oil companies, the Sun Oil Company and Great Canadian Oil Sands. Until 2010, Suncor marketed products and services to retail customers in Ontario through a downstream network of 780 company-owned, and 700 customer-operated retail and Diesel fuel sites, primarily in Ontario under the Sunoco brand. In 2009, Suncor acquired the former Crown corporation Petro-Canada, which replaced the Sunoco brand across its existing outlets. Suncor also markets through a retail network of Shell and ExxonMobil branded outlets in the United States.