Herb Greenberg

Herb Greenberg: "'No. We've been here before, and the consequences -- though not always immediate -- have invariably been bad. There is not a single instance in historical data since 1871 when the S&P 500 traded above 18-times record earnings and there was not a low a year or more later that erased every bit of advantage over Treasury bills. Not one.'

He concludes, 'Simply put, there is no investment merit to the stock market at these valuations.'"