"By 2007, yield-seeking speculation had driven stocks to a second bubble peak. A few weeks before that market extreme, which would be followed by a 55% plunge in the S&P 500, I reminded investors:
'Remember, valuation often has little impact on short-term returns (though the impact can be quite violent once internal market action deteriorates, indicating that investors are becoming averse to risk). Still, valuations have an enormous impact on long-term returns, particularly at the horizon of 7 years and beyond. The recent market advance should do nothing to undermine the confidence that investors have in historically reliable, theoretically sound, carefully constructed measures of market valuation.
'Indeed, there is no evidence that historically reliable valuation measures have lost their validity. Though the stock market has maintained relatively high multiples since the late 1990's, those multiples have thus far been associated with poor extended returns. Specifically, based on the most recent, reasonably long-term period available, the S&P 500 has (predictably) lagged Treasury bills for not just seven years, but now more than eight-and-a-half years. Investors will place themselves in quite a bit of danger if they believe that the ‘echo bubble’ from the 2002 lows is some sort of new era for market valuations.†'
John Hussman, Weekly Commentary 6/12/2017