Michael Rubens Bloomberg is an American business magnate, politician and philanthropist. He served as the 108th Mayor of New York City, holding office for three consecutive terms beginning with his first election in 2001. With a net worth of $33 billion, he is the eleventh-richest person in the United States and the sixteenth-wealthiest in the world.
He is the founder and 88% owner of Bloomberg L.P., the global financial data and media company notable for its Bloomberg Terminal.
Bloomberg began his career at the securities brokerage Salomon Brothers before forming his company in 1981 and spending the next twenty years as its Chairman and CEO. He also served as chairman of the board of trustees at his alma mater Johns Hopkins University from 1996 to 2002. A Democrat before seeking elective office, Bloomberg switched his party registration in 2001 to run for mayor as a Republican. He defeated opponent Mark Green in a close election held just weeks after the September 11 terrorist attacks. Bloomberg won a second term in 2005 and left the Republican Party two years later. He campaigned to change the city's term limits law and was elected to his third term in 2009 as an independent candidate on the Republican ballot line.