Warren Buffett on Tuesday donated about $4 billion to the Bill & Melinda Gates Foundation Trust and four family charities, part of the billionaire’s pledge to give away nearly all of his net worth.

Berkshire Hathaway Inc., which Buffett has run since 1965, said the donation comprises about 14.4 million of its Class B shares, whose closing price on Tuesday was $277.64.

Eleven million shares will go to the Bill & Melinda Gates Foundation, and 1.1 million will go to the Susan Thompson Buffett Foundation, named for Buffett’s late first wife.

Another 770,000 shares will also go to each of three charities run by Buffett’s children Howard, Susan and Peter: the Howard G. Buffett Foundation, the Sherwood Foundation and the Novo Foundation.

Since 2006, the 91-year-old Buffett has donated more than half of his Berkshire shares, with the donations worth about $45.5 billion at the time they were made.

Despite the donations, Buffett still owns approximately 16 percent of Berkshire and controls about one-third of its voting power.

Both percentages have been fairly stable in recent years because Berkshire has aggressively repurchased its own stock.

Buffett has built Omaha, Neb.-based Berkshire into a more than $600 billion conglomerate, owning dozens of businesses such as the BNSF railroad and Geico auto insurance, and stocks such as Apple Inc. and Bank of America Corp.

He and Bill Gates also pioneered “The Giving Pledge,” where more than 200 people like Michael Bloomberg, Larry Ellison, Carl Icahn, Elon Musk and Mark Zuckerberg committed at least half their fortunes to philanthropy.

(Reporting by Jonathan Stempel in New York and Manya Saini in Bengaluru;Editing by Vinay Dwivedi and Cynthia Osterman)