Warren Buffett donates $4 billion of Berkshire Hathaway stock, cutting his net worth to below $100 billion

• Warren Buffett donated $4 billion worth of Berkshire Hathaway stock to good causes on Tuesday.
• He gifted the shares to the Bill & Melinda Gates Foundation and four other philanthropic groups.

Warren Buffett donated $4 billion worth of Berkshire Hathaway stock to philanthropic groups on Tuesday, trimming his net worth to below $100 billion.

The famed investor pledged in 2006 to gradually give more than 99% of his wealth to good causes, and has gifted about 52% of his Berkshire shares since then. The donations have slashed his fortune from around 475,000 "A" shares, which would have been worth $197 million as of Tuesday's close, to 229,000 "A" shares worth $95 billion.

Buffett converted 9,608 Berkshire "A" shares, valued at $415,500 each as of Tuesday's close, into about 14.4 million of his company's much cheaper "B" shares, he said in a statement this week.

He gave around 11 million of those shares to the Bill & Melinda Gates Foundation, 1.1 million shares to the Susan Thompson Buffett Foundation, and 770,000 shares to each of his three children's charities: the Sherwood Foundation, the Howard G. Buffett Foundation, and the NoVo Foundation.

"I'm grateful for Warren's gifts to support the foundation's work and for our many years of friendship," Gates tweeted on Tuesday. "When he decided in 2006 to make these gifts, it moved me to tears. It still does."

All else being equal, if Buffett hadn't donated a single share, he would currently be number two on the Bloomberg Billionaires Index after Elon Musk — not several spots behind the Tesla and SpaceX CEO.

Despite his gifts, Buffett still owns close to 16% of Berkshire's outstanding stock. He also commands around 31% of the voting rights, as "A" shares carry far more influence than "B" shares.

Buffett marked the halfway point in his giving last year by sharing his views on wealth and philanthropy. The investor noted that giving away surplus money was the "easiest deed in the world," but distributing it effectively and leveraging it to tackle complex problems was much trickier.

The Berkshire chief also framed his vast fortune as a byproduct of his passion for investing. "Society has a use for my money; I don't," he said.

The Buffett family has been busy on the charity front recently. The investor's charity-lunch auction, scheduled to end on Friday, has already attracted a $3 million offer. The winning bidder and up to seven companions will be invited to have lunch with Buffett, and the auction proceeds will be donated to Glide, a homeless charity in San Francisco.

Buffett's elder son, Howard, met with Ukrainian President Volodymyr Zelenskyy in Kyiv last week to discuss ways to support the nation as it continues to fend off a Russian invasion. The Howard G. Buffett Foundation has since donated $2.7 million to help fund the delivery of nine passenger buses to Ukrainian forces, and to finance the transport of 375 trauma kits to citizens on the front lines, CNBC reported.

Read more: Insider recently interviewed the CEOs of 5 Berkshire Hathaway businesses: See's Candies, Dairy Queen, Borsheims, Cort, and Brooks Running. They offered a rare glimpse inside Warren Buffett's company, and shared how they're dealing with the pandemic and inflation.