Warren Buffett has donated another US$5.3 billion of Berkshire Hathaway stock to five charities, his biggest annual donation since he began making them in 2006.

The annual donation announced on Friday consists of about 13 million of Berkshire's Class B shares.

Buffett is donating 9.93 million shares to the Bill & Melinda Gates Foundation.

He is also donating 993,035 million shares to the Susan Thompson Buffett Foundation, named for his late first wife, and 695,122 shares to each of three charities led by his children Howard, Susan and Peter: the Howard G Buffett Foundation, the Sherwood Foundation and the NoVo Foundation.

Buffett, 93, plans to give away more than 99% of the fortune he built at Omaha, Nebraska-based Berkshire, the conglomerate he has run since 1965.

Despite having given away more than half of his Berkshire shares, Buffett is still worth US$134.3 billion, making him the world's eighth richest person, according to Forbes magazine.

  - Reuters