On 16th June, Bill and Melinda Gates – along with Warren Buffett – publicly asked the billionaires of the US to pledge the majority of their wealth to philanthropy. While they have begun with US billionaires, the trio hopes to expand 'The Giving Pledge' movement to their counterparts across the globe. Analysts immediately began to calculate what success might mean in dollar terms, with estimates as high as an additional $600bn (£398bn).
