(Reuters) - Warren Buffett is donating roughly $3.6 billion of Berkshire Hathaway Inc BRKa.N stock to five charities, including the Bill & Melinda Gates Foundation, the biggest contribution in Buffett's plan to give away his fortune.

FILE PHOTO - Berkshire Hathaway Chairman Warren Buffett walks through the exhibit hall as shareholders gather to hear from the billionaire investor at Berkshire Hathaway Inc's annual shareholder meeting in Omaha, Nebraska, U.S., May 4, 2019. REUTERS/Scott Morgan

Berkshire said Buffett’s 14th annual donation comprises about 16.81 million Class “B” shares of Berkshire.

The donation will boost the total amount Buffett has given to the charities to more than $34.5 billion since the 88-year-old billionaire pledged in 2006 to give his shares away.

Four-fifths of the donations go to the Gates Foundation. The rest goes to the Susan Thompson Buffett Foundation, named for Buffett’s late first wife, and charities run by his children Howard, Susan and Peter: the Howard G. Buffett Foundation, the Sherwood Foundation and the NoVo Foundation.

Buffett has since 1965 built Berkshire into a roughly $522 billion conglomerate owning such businesses as the BNSF railroad, Geico auto insurance and Dairy Queen ice cream, and stocks such as Apple Inc AAPL.O and Wells Fargo & Co WFC.N.

Buffett’s largest prior annual donation was $3.4 billion in 2018.

Following the latest donation, Buffett will still own about 15.7 percent of Berkshire, despite having given away 45 percent of his 2006 holdings, and have roughly 31 percent of its voting power.

Buffett remains the world’s fourth-richest person, worth $87.5 billion according to Forbes magazine.

Jeff Bezos, Amazon.com Inc's AMZN.O chief executive, and his family topped Forbes' list at $157.8 billion. Berkshire invested in Amazon for the first time early this year.

The Gates and family charities typically sell Buffett’s shares to finance their activities, reflecting his desire that money be spent. Buffett also donates to other charities.