GREAT cornering and eye-popping acceleration make Porsche’s cars popular among thrill-seeking bankers and hedge-fund managers. Now its clients are discovering that the carmaker itself has an unexpected talent for cornering markets. In a few tumultuous days it is thought to have made a cool €6 billion-12 billion ($7.5 billion-15 billion) on the share price of Volkswagen (VW)—a coup that has roiled the world’s financial markets.nullnullnull