Warren Buffett, chairman, CEO, and largest shareholder of American multinational conglomerate Berkshire Hathaway, has donated company shares valued at $3.4bn to charities.

In a news release, Berkshire Hathaway said 11,867 of Buffett's Class-A shares were converted into 17,800,500 Class-B shares – 17,696,780 of which Class-B shares have been turned over to the Bill & Melinda Gates Foundation, the Susan Thompson Buffett Foundation, the Sherwood Foundation, the Howard G. Buffett Foundation, and the NoVo Foundation.

The move is pursuant to Buffett's 2006 pledge to donate 85% of his stake in Berkshire Hathaway to the foundations through annual gifts that will be completed 10 years after his estate is settled.

With Buffett's most recent gift, about 43% of his 2006 holdings have been given to the five foundations, with a total value of about $31bn based on the value at the time of the gifts.

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