Sara Blakely, the founder of the women’s undergarment company Spanx, is one of nine new billionaires to sign The Giving Pledge—a campaign in which billionaires pledge to give at least half of their wealth to charitable causes. The Giving Pledge was launched in 2010, and started as an idea of Warren Buffet and Bill and Melinda Gates. The 42-year-old Blakely joins a list of more than 100 other billionaires who have signed the pledge, including Richard Branson and his wife Joan, Larry Ellison, Michael Bloomberg, George Lucas and Mark Zuckerberg …
