WASHINGTON, Feb. 10 (UPI) -- Heavyweight U.S. philanthropists, especially those who are living, beefed up their charitable giving in 2013, the Chronicle of Philanthropy said Monday.
The top 50 U.S. gift-givers in 2013 increased their charitable donations by 4 percent from 2012 to 2013, the Chronicle reported. But gift giving among wealthy living philanthropists surged in the year.
The total of $6.2 billion pledged by living donors who are in the top 50 is nearly equal to what that category of givers donated in 2011 and 2012 combined, the Chronicle said.
In a year in which the stock market made solid gains, the wealthy wrote big checks. The largest single check for a charity was written by Facebook co-founder Mark Zuckerberg and his wife Priscilla Chan -- a gift of nearly $1 billion pledged to the Silicon Valley Community Foundation.
Zuckerberg and Chan made the largest donations in 2013 and were the youngest in the top 50.
As a group, the top 50 gave away $7.7 billion in the year, the Chronicle said.
Second on the list was George Mitchell, who made his fortune by developing the controversial mining method of hydraulic fracturing, commonly known as fracking.
Mitchell's gift of $750 million went to a family foundation that is dedicated to environmental issues. In short, Mitchell, who died last year, donated money to ensure fracking would be done as safely as possible, the Chronicle said.
Phil Knight, who co-founded Nike, and his wife Penelope were third on the list, pledging $500 million to the Oregon Health & Science University Foundation.
That gift is specifically for cancer research and comes with a catch: To receive the funds, the foundation must raise a matching amount within two years.
Keith Todd, the head of fund raising at the university, said there was no chance he would ignore the challenge.
"I have no intention of leaving $500 million sitting on the sidelines come December 2015," he said.
Fourth and fifth on the list are former New York City Mayor Michael Bloomberg and former hedge fund manager John Arnold and his wife Laura.
The Chronicle of Philanthropy said 19 of the top 50 are among the 122 wealthy individuals who have signed a charitable donation pledge known as the Giving Pledged that was begun by billionaires Bill and Melinda Gates and Warren Buffett.