No. 2 -- New York City Mayor Michael Bloomberg
NET WORTH: $18 billion
The founder of Bloomberg LP and current Mayor of New York City, who is constantly rumored to be mulling a run for President (a rumor categorically denied by Bloomberg), he rose to prominence at Salomon Brothers as head of equity trading. After Bloomberg left Salomon, he poured his knowledge of trading into the creation of what were first known as Market Masters terminals. Bloomberg signed on Merrill Lynch as his first client.The financial information and trading system would ultimately become Bloomberg LP.
Bloomberg is as well known for his wealth as for his shunning of some of the usual accoutrements of the high life, riding the subway to work as Mayor of New York, working at a cubicle, and turning down the chance to live in New York's Gracie Mansion, the official Mayor's residence.Bloomberg's move up the billionaire ranks has come lately, with Bloomberg making his greatest strides during the recession that took some other notable billionaires down in the rankings. Bloomberg moved from 142nd to 17th in the Forbes list of the world's billionaires in only two years, between 2007 and 2009. Bloomberg's ranking among the Buffett/Gates pledges is no surprise, as he already ranks among the Top 10 philanthropists in the U.S., according to the Chronicle of Philanthropygiving away as much as $250 million annually in recent years. Bloomberg and Gates have worked together previously. In 2008, Bloomberg and Gates announced a combined donation of $500 million to help governments in developing countries execute on anti-tobacco campaigns. Bloomberg has famously remarked on his plans to give away his fortune, quipping, "I am a big believer in giving it all away and have always said that the best financial planning ends with bouncing the check to the undertaker." Which leads us to the No. 1 richest American taking the Buffett/Gates pledge -- and along with Bloomberg one of only two members of the Forbes ranking of the 10 Richest Americans -- who is...