NEW YORK (NYTIMES) - George Soros, the billionaire hedge fund manager and a major Democratic donor, has given US$18 billion (S$24.3 billion) to his Open Society Foundations, one of the largest transfers of wealth ever made by a private donor to a single foundation.

The gift, made quietly over the past several years but disclosed only on Tuesday (Oct 17), has transformed Open Society into the second-biggest philanthropic organisation in the United States, behind the Bill and Melinda Gates Foundation. It will also place Soros, a lightning rod for conservative critics, squarely in the middle of the social and political debates convulsing the country.

Founded by Soros more than 30 years ago, Open Society promotes democracy and human rights in more than 120 countries. In recent years, the organisation has increased its attention on the United States, investing in programmes to protect gays and lesbians and reduce abuses by the police.

The organisation funded treatment centres during the 2014 Ebola outbreak, a centre for Roma art and culture, and efforts to protect people in the United States from what it described as "a national wave of hate incidents" after the 2016 election.

His political focus - including large donations to Hillary Clinton and other Democratic politicians - has made Soros, 87, a target of the right. Conservative website Breitbart has accused Soros of attempting to make Ireland a "pro-abortion country" and undermining the control of European countries over their borders.

Soros' philanthropy is rooted in his past.

He lived in Nazi-occupied Hungary as a boy. With Budapest under communist rule in 1947, he left for London and then the United States, where he found success on Wall Street.

As his fortune grew, Soros began funding efforts to promote democracy and human rights, establishing the first Open Society foundation in Hungary in 1984.

For decades, Soros funded the Open Society Foundations through donations of around US$800 million or US$900 million per year. But beginning a few years ago, he increased his contributions as part of his estate planning, bringing the organisation's endowment to about US$18 billion this year. The total donation figure was first reported by The Wall Street Journal.

Soros is expected to contribute at least another US$2 billion in the coming years.