Buffett has never sold any shares in Berkshire, the giant American conglomerate, but has donated about 45 per cent of his 2006 holdings to five charities.
He has said he intends to give his - entire stake in Berkshire to philanthropy through annual gifts that will be completed a decade after his estate is settled.
Buffett, 88, is the world's third-richest man, according to the 2019 Forbes rich list, with an estimated net worth of US$82.5 billion ($123 billion).
In May, Berkshire Hathaway, which manages assets equivalent to the size of the Swiss economy, revealed profits for the first quarter of US$21.7 billion ($32.5 billion), up significantly from the $1 billion loss reported a year ago.
Jim Walton, the youngest son of Walmart founder Sam Walton, also pledged this week to donate shares worth about $1.2 billion ($1.8 billion).
More than 11 million shares were - donated to an undisclosed recipient just a day after his elder brother Rob donated 135,000 shares worth US$15m ($22.5m). Family members have regularly donated to the Walton Family Foundation, whose causes include education and the environment.
