The Dow Jones Sustainability North America Index (DJSI North America) coversthe leading 20% in terms of sustainability of the 600 biggest North American companies in the Dow Jones Global Total Stock Market Index. The Dow Jones Sustainability United States Index (DJSI United States) is the US subset of the DJSI North America. This set of indeces was introduced in September 2005. The Dow Jones Sustainability North America 40 Index (DJSI North America 40) and the Dow Jones Sustainability United States 40 Index (DJSI United States 40) are subsets of the DJSI North America which track the largest 40 sustainability leaders in North America respectively the United States. The DJSI North America 40 and the DJSI United States 40 were launched in August 2008.