4. Pierre Omidyar, U.S.

Donations: $1.2 billion

Net worth: $8.2 billion

Born in 1967, he is a French-born American Iranian entrepreneur and philanthropist, who is the founder and chairman of the eBay auction site. Omidyar became very rich when eBay's went for IPO in 1998. Since then he has been focused on giving the bulk of his fortune away. He has funded tech incubators in Africa, new forms of grass-fed beef production in Hawaii and Humanity United, an organization dedicated to ending human trafficking and sex slavery, amongst other initiatives.

5. Michael Dell, U.S.

Donations: $1.2 billion

Net worth: $14.6 billion

Born in 1965, he is an American business magnate and author. He is the founder and CEO of Dell, one of the world’s leading sellers of personal computers. He is ranked as the 41st richest person in the world. In 1999 Michael and his wife Susan Dell started their foundation, which focuses on improving lives of poor urban children. Their money provides scholarships for high achievers and backs inventive charter schools. It also has a program to fight childhood obesity in the U.S., and is now working to improve lives of children living in India's urban slums.

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