Warren Buffett is donating approximately $6 billion worth of Berkshire Hathaway shares as part of his billionaire-investor pledge to give away most of his fortune.

The latest round of donations includes about 12.36 million Class B shares of Berkshire, the company said in a release on Saturday. Buffet’s net worth as of Friday was $152 billion, according to the Bloomberg Billionaires Index.

Roughly 9.43 million of the shares will go to the Bill & Melinda Gates Foundation Trust, founded by Microsoft co-founder Bill Gates and his ex-wife Melinda French Gates, which Buffett has supported for nearly two decades.

The remaining shares will be split among his children’s foundations—the Sherwood Foundation, the Howard G. Buffett Foundation, the NoVo Foundation—as well as the Susan Thompson Buffett Foundation, named after his late wife.

The donations, set to be completed on Monday, will reduce Buffett’s stake in Berkshire to 198,117 Class A shares and 1,144 Class B shares.

Buffett, 94, launched the Giving Pledge in 2010 alongside Bill and Melinda Gates, committing to donate most of his wealth during his lifetime, or upon his death. He began major philanthropic contributions four years before that, donating billions to the Gates Foundation and charitable organizations tied to his family members.

“The mathematics of the lifetime commitments to the five foundations are interesting,” Buffett said, according to the release. “The five foundations have received Berkshire B shares that had a value when received of about $60 billion, substantially more than my entire net worth in 2006.”

According to Buffett, he has never sold a single share of Berkshire, and has no intention of doing so. He said he converted A shares into B shares before making contributions.

“I have no debts and my remaining A shares are worth about $145 billion, well over 99 percent of my net worth,” Buffett said. “My will provides that about 99.5 percent of my estate is destined for philanthropic usage.”

In 1965, Buffett famously took control of Berkshire Hathaway, a then-large but struggling textile maker in Omaha, Nebraska, through an investment partnership. The textile business shut down in 1985, but Buffett kept the Berkshire name as he transformed the company into one of the most successful conglomerates in history.

Reflecting on the company’s success, Buffett said that “nothing extraordinary” had happened at Berkshire, instead attributing its rise to “a very long runway, simple and generally sound decisions, the American tailwind, and compounding effects.”

At Berkshire Hathaway’s annual shareholders’ meeting in May, Buffett said he would step down as CEO by the end of the year. Greg Abel, his long-time second-in-command who oversees Berkshire’s non-insurance businesses, will take over the role.

Bloomberg Billionaires Index currently ranks Buffett as the eighth-richest person in the world. The seven people above him (in ascending order) are Larry Page, Steve Ballmer, Bill Gates, Larry Ellison, Jeff Bezos, Mark Zuckerberg, and Elon Musk.