Facebook founder and CEO Mark Zuckerberg was America's most generous donor in 2013, giving nearly $1bn (€731m) of his fortune to charity.
The Chronicle of Philanthropy, which tracks charitable giving in the United States, said Mr Zuckerberg and his wife Priscilla Chan gave 18 million shares of Facebook stock, valued at some $992 million, to the Silicon Valley Community Foundation.
The Mountain View California-based foundation specialises in investment and management of charitable funds, with some $4.7bn in assets under management.
Over the past two years, Mr Zuckerberg and his wife, a physician, have given 36 million Facebook shares to the fund, valued at about $1.5 billion.
The couple dedicated their 2012 funds managed by the group for health and education.
Mr Zuckerberg, who turns 30 later this year, is the youngest benefactor ever to top the annual charitable donations list.
In September his net worth was estimated by Forbes magazine at $19bn, making him the 20th richest in the United States.
That figure is believed to have shot up, however, thanks to a healthy rise in the value of Facebook shares, and now is approaching $30bn, the market intelligence firm Wealth-X estimated recently.
Last year, the Facebook founder and his wife occupied the number two spot in charitable giving, making donations of nearly $500m in 2012.
First place went to billionaire investor Warren Buffett, who gave about $3 billion to charity in 2012.