This list of billionaires is base on an annual ranking of the world's wealthiest people compiled and published by Forbes magazine on 8 March, 2007. Forbes is an American, national business magazine. There are 946 billionaires on Forbes list, with 178 newcomers and 17 returning after being delisted from previous lists. The first 100 billionaires are listed here, and the billionaires ranked 102–946 are found at List of billionaires (2007) 102-946. The total net worth is an estimate measured in United States dollars, based on the closing stock prices of the stock exchanges on which each person's company is listed on, and exchange rates on 9 February 2007. Stock prices are defined as shares of ownership in a corporation, and exchange rates are defined as how much one currency is worth in terms of another. This list only represents each person's valuation on a single day due to daily fluctuations among exchange rates and stock valuations. The combined net worth of the list is US$3.5 trillion, a US$900 billion increase from 2006.