India, Oct. 27 -- John and Laura Arnold, former hedge fund billionaires, have become one of the world's kindest philanthropists, contributing over $2 billion, or 42% of their $2.9 billion net worth.

The couple has made the donation via the Giving Pledge, a campaign started by Warren Buffett, Melinda French Gates, and Bill Gates that encourages wealthy people to donate at least half of their net worth to charity.

John Arnold has a charity score of five out of five on Forbes' scale, which is only given to people who have donated more than 20 percent of their income, according to Fortune. Bella DeVaan, report co-author of a Giving Pledge, hailed the Arnolds latest move, saying that "They've boldly decided to give and study how philanthropy...