Ten more billionaires have signed on to the Giving Pledge, which enters its fifth year.
The effort, started by Warren Buffett and Bill and Melinda Gates, encourages billionaires to give the majority of their wealth to philanthropic causes.
Those joining the list this year cited a number of causes—from helping refugees to advancing medical research—that they will support, as well as many sources of inspiration for their decision.
"My philanthropic DNA was inherited from my mother, who dedicated her life to the service of others," said John "Jay" Jordan, the co-founder of private equity firm the Jordan Co. "[She] told me that in her view the true measure of financial philanthropy is not how much one gives but how much one has left after one gives. That sets the bar pretty high and would suggest that perhaps a 50 percent hurdle is too low."