The Rio Tinto Group is a diversified, British-Australian, multinational mining and resources group with headquarters in London and Melbourne. The company was founded in 1873, when a multinational consortium of investors purchased a mine complex on the Rio Tinto river, in Huelva, Spain from the Spanish government. Since then, the company has grown through a long series of mergers and acquisitions to place itself among the world leaders in the production of many commodities, including aluminium, iron ore, copper, uranium, coal, and diamonds. Although primarily focused on extraction of minerals, Rio Tinto also has significant operations in refining, particularly for refining bauxite and iron ore. The company has operations on six continents but is mainly concentrated in Australia and Canada, and owns gross assets valued at $81 billion through a complex web of wholly and partly owned subsidiaries. In 2007, the company was valued at $147 billion. Its head office in the United Kingdom is in the City of Westminster, London, while its Australian head office is in the City of Melbourne.
Rio Tinto Group is a dual-listed company traded on both the London Stock Exchange where it is a component of the FTSE 100 Index and the Australian Securities Exchange where it is a component of the S&P/ASX 200 index. As of March, 2009, Rio Tinto is the fourth-largest publicly listed mining company in the world with a market capitalisation of approximately $34 billion, and was listed in Fortune magazine's 2008 Global 500 ranking of largest worldwide companies by revenue at number 263. Although the company has a long record of producing profitable operating results and favourable investment returns, the company's 2007 acquisition of Canadian aluminium company Alcan for $38.1 billion burdened Rio Tinto with substantial debt.