When Warren Buffett so much as scratches his nose, the investment world sits up and takes notice. So the Buffettologists will be all over the latest acquisition by the world’s smartest investor. While his rivals were still digesting their sprouts, Mr Buffett announced on the evening of Christmas Day that Berkshire Hathaway was paying $4.5 billion (£2.25 billion) for majority control of Marmon Holdings, an industrial conglomerate owned by the Pritzker family of Chicago. Outside his insurance company investments, this is Mr Buffett’s biggest deal yet. Given Berkshire’s investment preferences, there were few surprises in the deal. Marmon’s products are...