Warren Buffett donates $27m in Berkshire stock to charity

'Oracle of Omaha' has donated $51.5 billion since 2006

Berkshire Hathaway chairman and chief executive Warren Buffett. AP

Warren Buffett has donated $27 million of Berkshire Hathaway stock to an unidentified charity.

The donation was made on Tuesday when Berkshire shares closed at $538,107. The donation was disclosed in a filing with the US Securities and Exchange Commission on Wednesday night, Reuters reported.

Mr Buffett, 92, has been donating Berkshire stock for years as part of his long-running plan to give away his billions of dollars.

He donated $4.6 billion worth of the stock in June. He has given $51.5 billion since 2006, Forbes reported.

The "Oracle of Omaha" has said that 99 per cent of his net worth will go to charity.

He also plans to donate all of his Berkshire shares through yearly gifts, which NBC has reported will be completed 10 years after his estate is settled.

Mr Buffett's latest donation is in addition to his annual gifts to the Bill and Melinda Gates Foundation and charities overseen by his family.

He still holds 218,237 Class A shares of Berkshire stock, which were up to $539,680 a share on Thursday.

Berkshire owns many businesses including Geico insurance, BNSF Railway, an assortment of retail companies, utilities and more.

Agencies contributed to this report