New Delhi, Oct. 26 -- Former hedge fund billionaire John Arnold and his wife Laura have donated over $2 billion, about 42% of their $2.9 billion net worth, to the Giving Pledge-a platform that encourages world's richest people to give at least half their wealth during their lifetime or in their wills.

According to a report by Fortune, John Arnold has a Forbes philanthropy score of 5 out of 5, awarded to those who have given more than 20% of their wealth. "The Arnolds should be commended," said Bella DeVaan, co-author of a report on the Giving Pledge, "They've boldly decided to give and study how philanthropy can actually move money out the door instead of sequestering wealth."

Through their foundation, Arnold Ventures, launched in 2008,...