Giving Pledge, an organization created by Bill and Melinda Gates of the Microsoft fortune and Warren Buffet of the investment firm Berkshire Hathaway, released a list of 38 other billionaires and their families who have joined them in signing letters pledging to donate at least 50 percent of their fortunes to charitable causes of their own choosing.
"At its core, the Giving Pledge is about asking wealthy families to have important conversations about their wealth and how it will be used," Buffet said in a release on the organization's Web site. "We're delighted that so many people are doing just that -- and that so many have decided to not only take this pledge but also to commit to sums far greater than the 50 percent minimum level."
Among the 40 are New York Mayor Michael Bloomberg, financier T. Boone Pickens, filmmaker George Lucas, media mogul Ted Turner, oil fortune heir David Rockefeller and Microsoft co-founder Paul G. Allen.
"If you want to do something for your children and show how much you love them, the single best thing -- by far -- is to support organizations that will create a better world for them and their children," Bloomberg said in his pledge letter.
George Kaiser, chairman of BOK Financial Corp., said he made the commitment because it was clear to him he had a moral obligation to do so.
"I had the advantage of both genetics (winning the 'ovarian lottery') and upbringing," he said in his letter.
The complete list and letters are at www.givingpledge.org.