Michael Rubens Bloomberg (born February 14, 1942) is an American businessperson and politician who is currently Mayor of New York City. With a net worth of $25 billion in 2012, he is also the 10th-richest person in the United States. He is the founder and 88% owner of Bloomberg L.P., a financial data-services firm.
A Democrat before seeking elective office, Bloomberg switched his registration in 2001 and ran for mayor as a Republican, winning the election that year and a second term in 2005. Bloomberg left the Republican Party over policy and philosophical disagreements with national party leadership in 2007 and ran for his third term in 2009 as an Independent candidate on the Republican ballot line. He was frequently mentioned as a possible Independent candidate for the 2008 presidential election and his departure from the Republican Party fueled further speculation. There was also speculation that he would run as a vice-presidential candidate. Bloomberg did not, however, seek the presidency nor was he selected as a running mate by any of the presidential candidates.