George Soros, billionaire investor and philanthropist, is donating $100 million to Human Rights Watch in his largest ever gift.

Soros will announce the gift later today, The New York Times reported. It will be by far the largest gift that Human Rights Watch has ever received.

Philanthropic donations have been smaller this year thanks to economic uncertainty, with only one gift greater than $100 million, compared with six last year, according to Indiana University's Center on Philanthropy.

"We're seeing noticeably fewer charitable gifts at the $100 million level from individuals reported than we did just a few years ago," Patrick Rooney, the center's executive director, told The New York Times.

Soros, 80, told The New York Times that he plans to make a series of large gifts.