Warren Buffett on Monday donated roughly 3.17 billion US dollars of Berkshire Hathaway Inc stock to the Bill & Melinda Gates Foundation and four family charities, his largest contribution in a more than decade-long plan to give away his fortune.

Berkshire said Buffett, 86, has made 27.54 billion US dollars in donations since 2006 to the five charities, including roughly 21.9 billion US dollars to the Gates Foundation.‍

Students cheer the arrival of Berkshire Hathaway CEO Warren Buffett during the Berkshire Hathaway annual meeting weekend in Omaha, Nebraska, US, May 7, 2017. /VCG Photo

Buffett still owns about 17 percent of Berkshire, the Omaha, Nebraska-based conglomerate he has run since 1965, despite having donated more than 40 percent of his holdings.

The Gates Foundation, which focuses on improving health, reducing poverty and aiding education, receives about 2.42 billion US dollars of Monday's donations.

Buffett also donated to the Susan Thompson Buffett Foundation, named after his late first wife, and the Howard G. Buffett, Sherwood and NoVo Foundations, respectively overseen by his children, Howard, Susan and Peter.

Following Monday's donation, Buffet remained the world's fourth-richest person, according to Forbes magazine.

Berkshire Hathaway CEO Warren Buffett (R) plays bridge with Microsoft founder Bill Gates during the Berkshire Hathaway annual meeting weekend in Omaha, Nebraska, US, May 7, 2017. /VCG Photo

Gates is a close friend of Buffett and a Berkshire director. Buffett typically reduces the number of shares he donates by five percent from the prior year.

The charities usually sell the Berkshire shares to finance their activities, reflecting Buffett's desire that his money be spent. Buffett also makes smaller donations to other charities.

(Source: Reuters)