Warren Buffett has made another annual donation to five foundations, boosting his total charitable giving to more than $50 billion — significantly higher than his entire net worth in 2006 when he first scheduled the grants.

The 92-year-old legendary investor said Thursday he has converted over 9,000 Berkshire A shares into B shares in order to donate 13.7 million B shares to five foundations. A total of 10.5 million shares were delivered to the Bill & Melinda Gates Foundation Trust, and 1.05 million shares were donated to the Susan Thompson Buffett Foundation, named for his first wife, who died in 2004.

Another 2.2 million shares were split evenly among the three foundations run by his children: the Sherwood Foundation, the Howard G. Buffett Foundation and the NoVo Foundation. As of 1:30 p.m. ET, the B shares were worth about $336 apiece.

The “Oracle of Omaha” said the schedule for annual grants was made on June 26, 2006, when he owned $43 billion of Berkshire A shares, which represented more than 98% of his net worth. Buffett pledged in a 2006 letter to make annual gifts of Berkshire B shares throughout his lifetime for the benefit of the Bill & Melinda Gates Foundation. 

“During the following 17 years, I have neither bought nor sold any A or B shares nor do I intend to do so. The five foundations have received Berkshire B shares that had a value when received of about $50 billion, substantially more than my entire net worth in 2006,” Buffett said. “I have no debts and my remaining A shares are worth about $112 billion, well over 99% of my net worth.”

Last year, Buffett donated more than $750 million to the four foundations associated with his family on Thanksgiving eve as the “ultimate endorsement” in his children.

Buffett plans to give away all of his Berkshire shares through annual gifts, which will be completed 10 years after his estate is settled. After this year’s donation, Buffett now owns 218,287 A shares and 344 B shares.

“Nothing extraordinary has occurred at Berkshire; a very long runway, simple and generally sound decisions, the American tailwind and compounding effects produced my current wealth,” Buffett said. “My will provides that more than 99% of my estate is destined for philanthropic usage.”

The Omaha, Nebraska-based conglomerate, a sprawling empire with businesses ranging from insurance to railroads, and utilities to energy and retail, is now worth more than $730 billion.