A dozen more super-wealthy donors have signed a pledge started by Warren Buffett and Bill and Melinda Gates, promising to give away half of their wealth to charity.
The latest additions include hedge-fund manager Bill Ackman and his wife Karen and Elon Musk, the founder of Tesla Motors Inc., the initiative, Giving Pledge, said in a statement.
The twelve new signatories "come from different backgrounds, but share a common desire to see positive change in our world. We've said from the beginning that this is a long-term effort, but I'm particularly pleased to see continued momentum in encouraging greater and more thoughtful philanthropy," said Buffett, pledge co-founder and chairman and CEO of Berkshire Hathaway, in the statement.
The so-called Giving Pledge initiative describes itself as "an ongoing effort led by the pledgers themselves to help address society's most pressing problems by inviting the wealthiest American families and individuals to commit to giving more than half of their wealth to philanthropic causes and charitable organizations either during their lifetime or in their will."
Gates, 56, ranks as the world's second-richest person, with $62.7 billion, while Buffett, 81, is in the No. 3 slot, with $44.6 billion, according to the Bloomberg Billionaires Index.
The news comes just days after Buffett announced that he suffers from stage 1 prostate cancer.