The world's second wealthiest person, investor Warren Buffett, has announced he will give the bulk of his $44 billion fortune to a foundation run by the world's richest man, computer tycoon Bill Gates and his wife Melinda.

From left: Bill Gates, Melinda Gates and Warren Buffett

Buffett says he will leave five-sixths of his shares in the Omaha, Nebraska-based Berkshire Hathaway, which are worth more than $30 billion, to the Bill and Melinda Gates Foundation. Buffett will begin his donations starting in July.

Buffett will also give money to several other philanthropies, including foundations headed by his three children

The 75-year-old billionaire says he always planned to leave his money to a philanthropy after his death. But the 2004 death of his wife Susan hastened his decision.

"If you are accumulating wealth, it is very natural to go to someone you think can handle money better that you can and turn your money over to them and say 'you can do a better job than I can do making some money,' he said Monday. "Well, I have some people where I am saying "you can give it away better than I can so I am turning it over to you, and you do a better job of giving it away than I would'."

Bill Gates

The gift will double the size of the Gates Foundation, which is already the world's largest foundation, valued at more than $29 billion. Bill and Melinda Gates say they will use the money to deepen their work in areas the foundation currently focuses on, particularly global health and education, rather than expand to new areas. Buffett will join Bill and Melinda Gates as the third trustee of the Seattle-based Foundation.

Bill Gates recently announced that he will step away from his day-to-day role at the Microsoft Corporation over the next two years to work full-time with the Foundation.

Melinda Gates says the more the couple becomes involved in disease eradication, they more they want to do.

"We look very much at what diseases have the greatest impact on lives, where we can save the most lives? So for instance, there is a drug which in 2006 will hopefully become the first drug that the foundation in partnership with our grantee institute will hopefully bring to places like India and Bangladesh, where they have a disease call kala azar, black fever, that we really can save about 200,000 lives a year if you can get this drug out there at a much lower cost than the drugs that are available today," she said.

Warren Buffett

Buffett says he is leaving most of his fortune to philanthropy rather than his children because he does not believe in dynastic wealth. His children, he says, already have plenty of money and advantages.

"It is not in keeping with my view of how the world should operate to create huge amounts of dynastic wealth," he said. "I do not believe on inheriting your position in society based upon what womby says the gift is the largest charitable commitment in history.