I read John Hussman regularly and think he is one of the better mavens of data analysis, especially in a historical context. Let’s just look at a few paragraphs of his work from the last posting (www.hussmanfunds.com): "Investors who don’t rely much on historical research, evidence, or memory, the exuberance of the market here is undoubtedly enticing, while a strongly defensive position might seem unbearably at odds with prevailing conditions. For investors who do rely on historical research, evidence, and memory, prevailing conditions offer little choice but to maintain a strongly defensive position. Moreover, the evidence is so strong and familiar from a historical perspective that a defensive position should be fairly comfortable despite the near-term enthusiasm of investors. "There are few times in history when the S&P 500 has been within 1% or less of its upper Bollinger band (two standard deviations above the 20-period moving average) on daily, weekly and monthly resolutions; coupled with a Shiller P/E in excess of 18 – the present multiple is actually 22.3; coupled with advisory bullishness above 47% and bearishness below 27% - the actual figures are 51% and 24.5% respectively; with the S&P 500 at a 4-year high and more than 8% above its 52-week moving average; and coupled, for good measure, with decelerating market internals, so that the advance-decline line at least deteriorated relative to its 13-week moving average compared with 6-months prior, or actually broke that average during the preceding month. This set of conditions is observationally equivalent to a variety of other extreme syndromes of overvalued, overbought, overbullish conditions that we've reported over time. Once that syndrome becomes extreme - as it has here - and you get any sort of meaningful "divergence" (rising interest rates, deteriorating internals, etc), the result is a virtual Who's Who of awful times to invest. "Consider the chronicle of these instances in recent decades: August and December 1972, shortly before a bull market peak that would see the S&P 500 lose half of its value over the next two years; August 1987, just before the market lost a third of its value over the next 20 weeks; April and July 1998, which would see the market lose 20% within a few months; a minor instance in July 1999 which would see the market lose just over 10% over the next 12 weeks, and following a recovery, another instance in March 2000 that would be followed by a collapse of more than 50% into 2002; April and July 2007, which would be followed by a collapse of more than 50% in the S&P 500, and today. "The prior instances were sometimes followed by immediate market losses, and were sometimes characterized by extended top formations - which produce a sort of complacency as investors say 'see, the market may be elevated and investors may be over-bullish, but the market is so resilient that it’s ignoring all that, so there’s no reason to worry.' Ultimately, however, the subsequent plunges wiped out far more return than investors achieved by remaining invested once conditions became so extreme. We are in familiar territory, but that territory generally marks the mouth of a vortex. Based on ensemble methods that capture a century of evidence – from Depression-era data, through the New Deal, World War, the Great Society, the electronics boom, the energy crisis, stagflation, the great moderation, the dot-com bubble, the tech crash, the housing bubble, the credit crisis, and even the more recent period of massive central bank interventions – our estimates of prospective market return/risk have been negative since April 2010 and have remained negative even as new data has arrived. Since early March, those estimates have plunged into the most negative 0.5% of historical instances."