Warren Buffett continues to make good on his promise to give most of his enormous wealth to charity.

The billionaire investor gave away $2.9 billion worth of stock in his holding company Berkshire Hathaway (BRKA), according to an official filing Thursday. He's now made a huge donation 11 years in a row.

This year, Buffett is giving 19.6 million Class B shares to five charities. The bulk of the money, $2.2 billion, will go to the Bill and Melinda Gates Foundation.

Four other charities with links to the Buffett family will share the rest: Buffett's education-focused charity, which is named after his late wife Susan; the Nebraska-based Sherwood Foundation, chaired by their daughter; the Howard G. Buffett Foundation chaired by his son; and the NoVo Foundation, headed by Buffett's youngest son Peter.

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Buffett has been giving away his wealth for over a decade now. He gave the five foundations $2.8 billion worth of shares in 2015, following a gift of a similar size the year before that.

In 2010, Buffett launched the Giving Pledge with Bill and Melinda Gates. The effort encourages billionaires to commit to giving away most of their money during their lifetimes or in their wills.

The pledge isn't a legally binding contract, but more of a moral commitment. So far, 154 individuals and couples have joined the pledge.

-- Jackie Wattles contributed to this article