Coombs' first career job was in 1983 in the Latin American department at Grindlays Bank, which was later acquired by the Australia and New Zealand Banking Group. In 1998, he started Ashmore as a new division of the company. In 1999, Coombs led a management buyout, and took Ashmore public in 2006. He later bought the money manager Emerging Market Management. In 2007, he held 42.5% of the Ashmore Group.