Warren Buffett's annual letter to Berkshire Hathaway Inc. shareholders highlighted his optimism about the conglomerate's performance and the future of the American economy.<br />But the billionaire also used sections of the 31-page letter to again address criticism of some of Berkshire's business moves.<br />Mr. Buffett took pains to elaborate on his company’s controversial partnership with 3G Capital Partners LP, the investment firm that co-owns Kraft Heinz Co. and Burger King’s parent company Restaurant Brands International Inc. with Berkshire.<br />The two partners share the same goal of buying and holding large businesses but “follow different paths” in pursuit of that objective, Mr. Buffett wrote, justifying a relationship that some Berkshire shareholders have questioned.
