Mr. Soros’s 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.

In 1992, Mr. Soros made a $1 billion bet against the British pound, a trade that famously earned him the nickname “the man who broke the Bank of England” when his aggressive selling of the currency pushed the government to devalue the pound.

As his fortune grew, Mr. Soros began funding efforts to promote democracy and human rights, establishing the first Open Society foundation in Hungary in 1984. Mr. Soros took the name from a book by the philosopher Karl Popper, “Open Society and Its Enemies,” in which he argued for democratic governance, free expression and respect for individual rights.

“He lived through Nazi Hungary,” Ms. Heisman said. “He knows what it’s like to live in a closed society.”

Mr. Soros eventually became one of the biggest donors to Democrats, including Mrs. Clinton. During the last election cycle, Mr. Soros gave millions to super PACs that opposed Mr. Trump and supported other Democratic candidates and causes. He also bet big in the markets that Mr. Trump would lose the election, a wager that cost him about $1 billion.

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

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

“There is no foundation in the world, including the Ford Foundation, that has had more impact around the world than the Open Society Foundations in the last two decades,” said Darren Walker, president of the Ford Foundation. “Because there is no part of the world that they have not been. Their footprint is deeper, wider and more impactful than any other social justice foundation in the world.”