On December 19, 2013, Zuckerberg announced a donation of 18 million Facebook shares to the Silicon Valley Community Foundation, to be executed by the end of the month—based on Facebook's valuation as of then, the shares totaled $990 million in value. On December 31, 2013, the donation was recognized as the largest charitable gift on public record for 2013. "The Chronicle of Philanthropy" placed Zuckerberg and his wife at the top of the magazine's annual list of 50 most generous Americans for 2013, having donated roughly $1 billion to charity.