Facebook founder Mark Zuckerberg and his wife, Priscilla Chan, have propelled themselves to the top of the A-list of charitable giving.

Facebook CEO Mark Zuckerberg speaks at the Newseum (Win McNamee/Getty Images)

The Chronicle of Philanthropy reports the couple's donation of 18 million shares of Facebook stock, valued at more than $970 million, to a Silicon Valley nonprofit, made them the most generous American philanthropists in 2013.

The top 50 contributors made donations last year totaling $7.7 billion, plus pledges of $2.9 billion.

Chronicle editor Stacy Palmer says living donors gave the same amount last year as in the two previous years combined.

Some of the nation's biggest givers, like Warren Buffett or Microsoft co-founder Bill Gates and his wife, Melinda, do not appear on the 2013 list because their donations were counted as pledges in previous years.

Forty-two of the top 50 made gifts of $50 million or more.

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