Those "Giving Pledge" billionaires had better pick up the pace

In the latest report on billionaire philanthropy from the nonprofit Institute for Policy Studies, authors Helen Flannery, Chuck Collins, and Bella DeVaan use Forbes data to calculate that the 73 surviving American pledgers who were billionaires when the pledge was created in 2010 have more than doubled their collective wealth since then—and 30 individuals have seen their net worths at least triple. Behold the greatest hits.