Warren Buffett, 96, has formally completed his exit as chairman of Berkshire Hathaway after leading the company for 61 years. Berkshire delivered an annual return of 19.7% during his tenure. The company announced the transition on Sept. 18, roughly nine months after Buffett handed the chief executive role to Greg Abel. His older son, Howard G. Buffett, 71, became chairman under Berkshire’s succession plan, while Warren Buffett remains chair emeritus. Buffett told shareholders that serving as chairman had been the privilege of his lifetime and that he had never taken their trust for granted.