Billionaire investor Warren Buffett has ended donations to the Gates Foundation and will transfer approximately US$6 billion in Berkshire Hathaway stock to four foundations associated with his family.

The 95-year-old Berkshire chairman said Tuesday that he will convert 8,000 Class A shares into 12 million Class B shares before distributing them among the charities.

The Susan Thompson Buffett Foundation, named after his late wife, will receive nine million shares. The Sherwood Foundation, Howard G Buffett Foundation and NoVo Foundation will each receive one million shares. The latter three are overseen by Buffett’s children.

Buffett also set a deadline of December 31, 2034, to donate all his remaining Berkshire shares to the four organisations.

The latest distribution excludes the Gates Foundation, which has received more than US$47 billion in Berkshire stock since Buffett pledged in 2006 to donate much of his wealth to charity.

The decision comes amid scrutiny of Microsoft co-founder Bill Gates’ past interactions with convicted sex offender Jeffrey Epstein and an external review by the Gates Foundation of its previous engagements with Epstein.

Buffett did not refer to Epstein or explain the exclusion of the Gates Foundation in his announcement.

Gates told members of the United States Congress in June that he did not fully understand the extent of Epstein’s crimes when the two associated and said he never witnessed criminal conduct.

The Gates Foundation has said it did not employ Epstein or make payments to him.