(Reuters) - Warren Buffett on Monday donated roughly $3.17 billion of Berkshire Hathaway Inc stock to the Bill & Melinda Gates Foundation and four family charities, his largest contribution in a more than decade-long plan to give away his fortune. 
 
 Berkshire Hathaway CEO Warren Buffett (R) talks to Microsoft founder Bill Gates as they play Bridge during the Berkshire Hathaway annual meeting weekend in Omaha, Nebraska, U.S. May 7, 2017. REUTERS/Rick Wilking 
 
 The billionaire investor’s 12th annual donation to the five charities comprised 18.63 million Class “B” shares of Berkshire, valued at $170.25 each as of Monday’s market close. 
 
 Berkshire said Buffett, 86, has made $27.54 billion in donations since 2006 to the five charities, including roughly $21.9 billion to the Gates Foundation. 
 
 Buffett still owns about 17 percent of Berkshire, the Omaha, Nebraska-based conglomerate he has run since 1965, despite having donated more than 40 percent of his holdings. 
 
 The Gates Foundation, which focuses on improving health, reducing poverty and aiding education, is receiving about $2.42 billion of Monday’s donations. 
 
 Buffett also donated to the Susan Thompson Buffett Foundation, named for his late first wife, and the Howard G. Buffett, Sherwood and NoVo Foundations, respectively overseen by his children, Howard, Susan and Peter. 
 
 Following Monday’s donation, Buffet remained the world’s fourth-richest person, according to Forbes magazine. 
 
 Before the donations were announced, Forbes estimated Buffett’s net worth at $76.3 billion, trailing Microsoft Corp co-founder Bill Gates’ $89.4 billion, Amazon.com Inc founder Jeff Bezos’ $84.8 billion, and Spanish retailing magnate Amancio Ortega’s $81.8 billion. 
 
 Gates is a close friend of Buffett and a Berkshire director. 
 
 Buffett typically reduces the number of shares he donates by 5 percent from the prior year. 
 
 The charities usually sell the Berkshire shares to finance their activities, reflecting Buffett’s desire that his money be spent. Buffett also makes smaller donations to other charities. 

 Warren Buffett has parted ways with another chunk of his massive fortune. 
 
 The Oracle of Omaha gave away $3.17 billion in shares of his holding company, Berkshire Hathaway (BRKA), on Monday, according to a company statement. Buffett has donated billions to charity every year for more than a decade. 
 
 Per usual, the stock went to the Bill & Melinda Gates Foundation, as well as four foundations with ties to the Buffett family: Buffett's education-focused charity, which is named after his late wife Susan; the Sherwood Foundation, which is chaired by their daughter; the Howard G. Buffett Foundation, which is led by his son; and the NoVo Foundation, which has Buffett's youngest son Peter at the helm. 
 
 Including the 18.6 million Class B shares donated on Monday, Buffett has given a total of $27.54 billion to these groups. (See correction, below.) 
 
 Related: Why Warren Buffett says single-payer health care makes sense 
 
 In 2006, Buffett announced plans to gradually donate all his Berkshire Hathaway shares. 
 
 It was a promise that took on a new life in 2010, when Buffett launched The Giving Pledge with Bill Gates. The initiative encourages the world's billionaires to dedicate the majority of their wealth to philanthropic causes. 
 
 As of May, 170 people had signed the pledge across 21 countries. 
 
 Correction: An earlier version of this story misstated the number of Class B shares that Buffett donated.
– Warren Buffett remains the fourth-richest person in the world, but his pockets are now significantly lighter. As part of his annual giving spree, the billionaire announced Monday he would donate $3.17 billion in Berkshire Hathaway stock to five charities. The Bill and Melinda Gates Foundation will receive the largest share at $2.42 billion, reports Reuters, with the remainder split between family charities: the Susan Thompson Buffett Foundation, the Howard G. Buffett Foundation, the Sherwood Foundation, and the NoVo Foundation. Since 2006, Buffett has given $27.5 billion to the five groups, reports CNNMoney. (Buffett has vowed to give away 99% of his fortune.)