US financier George Soros has transferred $18bn to his foundation, an international grant-making network which works to promote democracy, human rights and freedom of the press.
The figure "reflects an ongoing process of asset transfer that has been under way for several years," according to his spokeswoman, Laura Silber.
She added that 87-year-old Soros "plans to leave the vast majority of his wealth to the Open Society foundations."
He is estimated to have amassed a fortune of more than $26bn.
Open Society operates through a network of more than 40 foundations and offices in countries from Afghanistan to South Africa.
Mr Soros, a Hungarian-born investor known for his risky financial bets, chairs OSF and three of his children are members of the board.
Open Society foundations is the second-richest in the US after the Bill & Melinda Gates Foundation, which has an endowment of over $40bn, according to the US National Philanthropic Trust.
