Citigroup Inc. is a major American financial services company based in New York City, formed from the merger of Citicorp and Travelers Group on April 7, 1998. According to Forbes Global 2000 in March 2007, it is tied for the world's largest company, with total assets of US $2.02 trillion. The company employs just under 300,000 staff around the world, and holds over 200 million customer accounts in more than 100 countries. It is a primary dealer in US Treasury securities and its stock is a component of the Dow Jones Industrial Average.
Citigroup and its predecessor companies use the "diversified financial services business model" first invented by Prudential in the late seventies. Simply put, this model attempts to conglomerate many types of finance companies, such as stock brokers, banks, insurance companies, and others. This is done because each of those businesses do better or worse at different times of the business cycle, and so owning all of them balances things out and creates in theory less earnings volatility. This is also done because customers usually use many different kinds of financial products and attempting to convince them to use more products from the same company sells more products more cheaply, compared to those separate companies strictly selling products on their own.