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. Facebook billionaire Zuckerberg married his longtime sweetheart, Priscilla Chan, last year. The two tied the knot in an intimate ceremony at his Palo Alto, Calif., home, in front of fewer than 100 people.
