The billionaire philanthropist transferred $18 billion to Open Society Foundations, a sprawling international group of charities that works in more than 100 countries on projects focused on refugee relief, public health and many other topics.
The $18 billion figure amounts to almost 80 percent of the financier's total net worth. Before the transfer, Soros had a net worth of $23 billion, according to a Forbes tally Tuesday. The site ranks him as the 29th wealthiest person in the world.
The donation catapulted Open Society Foundations to the front ranks of American charities based on total assets, the Journal reported, citing 2014 data. The only American charity larger than Open Society, the Bill and Melinda Gates Foundation, is also funded by a famous billionaire.
Soros began his charitable giving in 1979, nine years after launching Soros Fund Management, the hedge fund that would propel him into America's ultrawealthy. He has given away $12 billion in the four decades since, according to his official biography, available on his website.
His first charitable work involved providing black South Africans with scholarships during the country's apartheid. During the Cold War, he provided photocopiers to people living in eastern Europe in order to reprint texts banned by communist governments. He has also underwritten the largest effort to integrate Europe's Roma, according to the biography available on his website.
Soros and the Open Society Foundations did not immediately respond to a request for comment.