Bill Gates says he will donate 99% of his remaining tech fortune to the Gates Foundation, which will now close in 2045, earlier than previously planned. Only Berkshire Hathaway investor Warren Buffett's pledge to donate his fortune — currently estimated by Forbes at $160 billion — may be larger depending on stock market fluctuations. Gates' donation will be delivered over time and allow the foundation to spend an additional $200 billion over the next 20 years.