最新报道:Berkshire Hathaway has secretly accumulated a $4.7 billion position in an undisclosed stock over two quarters, with confidential SEC treatment preventing disclosure. Analysts speculate the mystery investment could be a wide-moat industrial stock like Lockheed Martin (down 10% YTD) or railroad companies Canadian National/Pacific, based on Buffett's criteria for durable competitive advantages. The position may be revealed in Berkshire's upcoming 13F filing on Thursday.