NEW YORK, Nov 22 ― Warren Buffett said yesterday he has donated about US$866 million (RM4.02 billion) of Berkshire Hathaway stock to four family charities, and told shareholders “I feel good” as he moves nearer the sunset of his storied investing career.

In a regulatory filing, Berkshire said Buffett donated 1.5 million Class B shares of Berkshire to the Susan Thompson Buffett Foundation. Named for his late first wife, the organisation works in reproductive health.

Buffett also donated 900,000 additional Class B shares, divided evenly among charities run by his children Howard, Susan and Peter: the Howard G. Buffett Foundation, the Sherwood Foundation and the NoVo Foundation.

The latest donations supplement the US$759 million of Berkshire stock that Buffett donated to the charities at this time last year, also just before the US Thanksgiving Day holiday.

Buffett also issued a rare letter to shareholders, maintaining that more than 99 per cent of his wealth would go to charity after his death, and Berkshire itself would remain in good hands.

While Buffett has curbed his non-Berkshire responsibilities over the years he has never publicly signalled a desire to step down, including after his prostate cancer diagnosis in 2012.

“At 93, I feel good but fully realise I am playing in extra innings,” Buffett said in the letter.

Berkshire did not immediately respond to a request for additional comment.

Greg Abel, a Berkshire vice chairman, is slated to succeed Buffett as Berkshire's chief executive, while Howard Buffett would become non-executive chairman.

Buffett is the world's fifth richest person, with a US$120.5 billion fortune, according to Forbes magazine.

He has since 2006 donated more than half his Berkshire stock to the family charities and the Bill & Melinda Gates Foundation.

These donations totalled close to US$52 billion at the time they were made, with the Gates Foundation receiving more than US$39 billion.

Buffett has run Omaha, Nebraska-based Berkshire since 1965.

The conglomerate owns dozens of businesses including the BNSF railroad, Geico car insurance, energy and industrial companies, and familiar consumer brands such as Dairy Queen and Fruit of the Loom.

It also owns hundreds of billions of dollars of stocks, led by Apple.

The Howard G. Buffett Foundation focuses on alleviating hunger, mitigating conflicts, combating human trafficking and improving public safety. The Sherwood Foundation supports nonprofits in Nebraska, and the NoVo Foundation has initiatives focused on girls and women. ― Reuters