In 1996, Buffett pledged 17.5 million Class B shares of his firm's stock to each of his children's foundations. Buffett, who turned 82 Thursday, said in an open letter how proud he is of the work they've accomplished with the funds and increased the pledge by 12.2 million shares each, Berkshire Hathaway said in a release.
"I knew you would apply your considerable brains and energies in order to make the most of the funds from my gift," Buffett said in the letter. "However, you have exceeded my high expectations. Your mother would be as proud of you as I am. I see her influence in what you are accomplishing."
Buffett's first wife, Susan, died in 2004.
Buffett said he expects the value of the annual distribution to average more than $100 million. "I'm confident you will use the money wisely, each in your own way," Buffett wrote.
CNNMoney says Peter Buffett runs the NoVo Foundation, which fights inequality and gender inequities. Howard Buffett runs the Howard G. Buffett Foundation, which works in the developing world to improve agriculture and clean water delivery. Daughter Susan Buffett runs the Sherwood Foundation, which funds early childhood education initiatives in the United States and supports non-profits in Omaha.