Suncor Energy is a Canadian integrated energy company based in Calgary, Alberta. It specializes in production of synthetic crude from oil sands. Suncor ranks number 134 in the Forbes Global 2000 list. Until 2010, Suncor marketed products and services to retail customers in Ontario through a downstream network of 280 branded as Sunoco, and 200 customer-operated retail and diesel sites. Following the acquisition of former Crown corporation Petro-Canada, Suncor converted its Sunoco stations (which were all in Ontario) to Petro-Canada sites in order to unify all of its downstream retail operations under the Petro-Canada banner throughout Canada. It also enabled the company to discontinue paying licensing fees for the Sunoco brand to Sunoco Inc. in the United States. Nationwide, Petro-Canadas upstream product supplier and parent company is Suncor Energy. Suncor also markets through a retail network of Phillips 66-branded outlets in Colorado. Suncor was founded in 1919 in Montreal as Sun Company of Canada, a subsidiary of Sun Oil (now Sunoco). In 1979, Sun formed Suncor by merging its Canadian refining and retailing interests; Great Canadian Oil Sands (a majority-owned subsidiary, which constructed and operated the first commercial plant to develop Canadas Athabasca oil sands and went on production in 1967); and its conventional oil and gas interests. In 1981, the Government of Ontario purchased a 25% stake in the company; it divested in 1993. In 1995 Sun Oil also divested its interest in the company, although Suncor maintained the Sunoco retail brand in Canada. Suncor took advantage of these two divestitures to become an independent, widely held public company.