America's Top Giver: Mark Zuckerberg

Mark Zuckerberg and his wife, Priscilla Chan, were the most generous American philanthropists in 2013, with a donation of 18 million shares of Facebook stock, valued at more than $970 million, to a Silicon Valley nonprofit in December. The Chronicle of Philanthropy says Zuckerberg's donation was the largest charitable gift on the public record in 2013 and put the young couple at the top of the magazine's annual list of 50 most generous Americans in 2013. The top 50 contributors made donations last year totaling $7.7 billion, plus pledges of $2.9 billion.

The Chronicle's editor says the most significant fact from the list was the amount of money coming from living donors, which totaled about the same amount as the two previous years combined. "It's a sure sign that the economy is getting better and people are getting a lot less cautious," she says. Ten of the 50 made the list because of bequests after their deaths, including the second biggest giver in 2013, Texas oil tycoon George Mitchell. At No. 3 were Nike chairman Philip Knight and his wife, Penelope, who made a $500 million challenge grant to Oregon Health & Science University Foundation for cancer research. (More Mark Zuckerberg stories.)