Warren Buffett is donating another $5.3 billion of Berkshire Hathaway stock to the Bill & Melinda Gates Foundation and four family charities, his biggest annual donation since he began making them in 2006.

Buffett’s donations boost his overall giving to the charities to about $57 billion, including to the family charities in the last two Novembers.

The latest donation, announced today, includes about 13 million Berkshire Class B shares.

Buffett is donating 9.93 million shares to the Gates Foundation, and has donated more than $43 billion of Berkshire shares there overall.

He is also donating 993,035 shares to the Susan Thompson Buffett Foundation, named for his late first wife, and 695,122 shares to each of three charities led by his children Howard, Susan and Peter: the Howard G. Buffett Foundation, the Sherwood Foundation and the NoVo Foundation.

Buffett, 93, plans to give away more than 99% of the fortune he built at Omaha, Nebraska-based Berkshire, which he has run since 1965, with his children serving as executors of his will.

Berkshire is an approximately $880 billion conglomerate that owns dozens of businesses including the BNSF railroad and Geico car insurance, and stocks such as Apple.

Despite having given away more than half of his Berkshire stock since 2006, Buffett still owns about one-seventh of the outstanding shares.

He was worth $134.3 billion before the latest donations, making him the world’s eighth richest person according to Forbes magazine.

In a statement, Buffett said he was worth about $44 billion when the donations began, but that the benefits of compounding, “simple and generally sound capital deployment” at Berkshire, and the “American tailwind” produced his current wealth.

Buffett, Bill Gates and Melinda French Gates also pioneered the Giving Pledge, in which 245 people like OpenAI’s Sam Altman, Michael Bloomberg, Elon Musk and Mark Zuckerberg committed at least half of their wealth to philanthropy.

The Susan Thompson Buffett Foundation works in reproductive health. The Howard G. Buffett Foundation works to alleviate hunger, mitigate conflicts including in Ukraine, and improve public safety. The Sherwood Foundation supports Nebraska nonprofits, and the NoVo Foundation has initiatives focused on girls and women.