Suncor Energy () 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 as the merger of its Canadian conventional and heavy oil companies, the Sun Oil Company Limited and Great Canadian Oil Sands Limited. 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 (owing to Suncor having originally been established as a subsidiary of Sunoco). 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 Colorado. History 1919–2000 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 Canada's 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. With these two divestitures, Suncor become an independent, widely held public company. 2000–present In 2003, Suncor acquired a refinery and associated Phillips 66 gas stations in Commerce City, Colorado from ConocoPhillips. In 2005, Suncor acquired a second Commerce City refinery from Valero Energy. Suncor moved its retail brand from Phillips 66 to Shell from 2009 to 2013. Suncor added the Exxon and Mobil brands in Colorado and Wyoming in 2015. On March 23, 2009, Suncor announced its intent to acquire Petro-Canada. This merger created a company with a combined market capitalization of C$43.3 billion. On June 4, 2009, a 98% approval rate was reached by Suncor's shareholders for the acquisition of Petro-Canada and the Competition Bureau approved the merger on June 21, 2009. The merger with Canada's 11th largest company was completed on August 1, 2009 in a $21 billion deal to form the second-largest