Apple Chief Executive Tim . Cook is joining the roster of the very rich who are giving away . their wealth. The head of the world's largest . technology corporation told Fortune magazine he plans to donate his . estimated $785million fortune to charity - after paying for his ten-year-old nephew's college education. 'You want to be the pebble in the pond that creates the . ripples for change,' Cook told the magazine. Scroll down for video . Philanthropic: Apple CEO Tim Cook plans to donate his estimated $785million fortune to charity, after he pays for his ten-year-old nephew's college education . Fortune estimated Cook's net worth, based on his holdings of . Apple stock, at about $120million. He also holds restricted . stock worth $665 million if it were to be fully vested. The 54-year-old CEO's revelation in Fortune's lengthy . profile of him is an example of the increasingly public . philanthropy of the world's richest people. Billionaire financier Warren Buffett is encouraging the very . wealthy to give away at least half their worth in their . lifetimes through the 'Giving Pledge,' whose website lists such . luminaries as Microsoft Corp's Bill Gates, Mark . Zuckerberg of Facebook Inc and Oracle Corp's . Larry Ellison. While Cook's largesse could not begin to approach the scale . of a Gates or Zuckerberg - both worth billions of dollars - the . Apple CEO told Fortune he hopes to make a difference. CEO: Cook (left) took over as the head of Apple when Steve Jobs (right) resigned in 2011. He is the only openly gay chief executive on the Fortune 500 list of biggest U.S. companies . Cook, who is not listed on the website, is known as an . intensely private person who shuns the spotlight on . philanthropy. In recent years, however, he has begun speaking out more . openly about issues ranging from the environment to civil . rights. Cook, who recently revealed he was gay, spoke out . against discrimination of the lesbian, gay, bisexual and . transsexual communities during his induction into the Alabama . Academy of Honor last year. He is the only openly gay chief executive on the Fortune 500 list of biggest U.S. companies, according to CNN. Former CEO of BP John Brown, who held the position from 1995 to 2007, only acknowledged he was gay after leaving office when an ex-boyfriend outed him. Cook took over Apple's CEO position in 2011 after Steve Jobs resigned. He told Fortune he has started donating money to unspecified . causes quietly and is trying to develop a more 'systematic . approach' to philanthropy that goes beyond writing checks.
Cook has an estimated $785million fortune, with a net worth of $120million . He has started donating money to unspecified causes quietly and is trying to develop a more 'systematic approach' to philanthropy . Other wealthy businessmen donating part of their fortune to charity include Warren Buffet, Bill Gates and Mark Zuckerberg .