In a 16-page letter, Buffett listed out fifteen common stock investments that at year-end had the largest market value. : Billionaire investor Warren Buffett revealed his much-anticipated letter to Berkshire Hathaway shareholders on Saturday. Buffett's letter to his company's shareholders, an annual exercise undertaken for more than 50 years, is a closely watched event on Wall Street as investors parse the statement for insights and wisdom on the economy and financial markets.