Berkshire Hathaway Inc., an investment company led by prominent US investor Warren Buffett, is considering purchasing more shares in Japan's five major trading houses, it was learned Saturday.

Warren Buffett says he's in the "urgent zone." It's the folksy billionaire's way of calling himself old. But even as Buffett approaches 90, the spotlight-loving chairman and CEO of Berkshire Hathaway isn't ready just yet to talk about who will run his giant company when he's gone. He still has more to say, and more to do - and that could make for an interesting year ahead.