Forty of America's billionaires and their families pledged Wednesday to give more than half of their fortune to charity in a drive organized by Bill Gates and Warren Buffett.
The group includes CNN founder Ted Turner, New York Mayor Michael Bloomberg, Oracle co-founder Larry Ellison and Hollywood director George Lucas, as well as Microsoft mogul Gates and investment guru Buffett.
The idea, announced just six weeks ago as "The Giving Pledge," was thought up by Gates and Buffett to convince billionaires to give most of their money - 50 percent or more - to charity.
"Forty of the wealthiest families and individuals in the United States have committed to returning the majority of their wealth to charitable causes," said a statement released Wednesday by www.givingpledge.org. "The pledge is a moral commitment to give, not a legal contract."
"We've really just started, but already we've had a terrific response," Buffett, the chief executive of the investment firm Berkshire Hathaway, said.
"At its core, the Giving Pledge is about asking wealthy families to have important conversations about their wealth and how it will be used."
Almost all on the list are self-made super-rich, such as media giant Bloomberg, and are worth about a billion dollars - or far more. A few represent longer-established fortunes, including David Rockefeller.
US billionaires have been out of favor with the public and politicians since the 2008 financial collapse. The pledge scheme might burnish their image.
But apart from good PR, the scheme raises the prospect of eye-popping amounts of money flowing to charity.
Gates and Buffett are reportedly aiming to secure pledges from each of the approximately 400 US billionaires. If the entire group were to surrender half of its wealth that would amount to some 600 billion dollars, Forbes magazine estimates.
Gates, the second richest man in the world according to the Forbes 2010 billionaires list, has some 53 billion dollars, narrowly losing his long-held number one spot to Mexican telecoms tycoon Carlos Slim, who has 53.5 billion.
Buffett, the second richest American, already announced in 2006 that he wanted gradually to give away all of his fortune estimated this year by Forbes at 47 billion dollars.
Rumors of the unprecedented drive first leaked in May 2009 when it emerged that Gates and Buffett had organized a secretive dinner for billionaires in New York City.
Ellison, the self-made man behind software giant Oracle, and with wealth estimated by Forbes at 28 billion dollars, called on others to join in.
Writing on the pledge website, Ellison said he had long ago decided to give away at least 95 percent of his fortune to charity and that he had already given away hundreds of millions of dollars.
"I will give billions more over time. Until now, I have done this giving quietly, because I have long believed that charitable giving is a personal and private matter," he wrote.
"Warren Buffett personally asked me to write this letter because he said I would be 'setting an example' and 'influencing others' to give. I hope he's right."