Ben Inker and Jeremy Grantham of Grantham, Mayo, Van Otterloo & Co. issued a quarterly letter suggesting the bull market cannot last much longer. Inker writes that the U.S. has been outperforming for decades but attacks the idea that US stocks are inherently superior even as they grow more expensive. “We cannot completely reject the possibility that those arguments are correct,” he says, “but the evidence seems pretty thin.” Grantham points to the need to address problems, saying: “we are dealing today with important issues, one so important that it may affect the long-term viability of our global society and perhaps even our species.”