Current stock market capitalization is largely an artifact of speculative psychology, not reasonably discounted cash flows. Unless investors rely on eternal sunshine of the spotless mind – the assumption that current levels of extreme cyclical optimism will be permanent – they should not expect the associated valuation extremes to be permanent either.

Market returns and economic growth have underlying drivers. At their core, extended periods of extraordinary growth and disappointing collapse reflect large moves in those drivers from one extreme to another. Extrapolation becomes a very bad idea once those extremes are reached.

Even when extreme “overvalued, overbought, overbullish” warning signs are present, we now require explicit deterioration in market internals before adopting a negative market outlook. That, however, is far different than saying that extreme conditions can be ignored altogether. With market internals negative here, underlying market risks may be expressed abruptly, and with unexpected severity.

The hallmark of an economic Ponzi scheme is that the operation of the economy relies on the constant creation of low-grade debt in order to finance consumption and income shortfalls among some members of the economy, using the massive surpluses earned by other members of the economy. The factors most responsible for today’s lopsided prosperity are exactly the seeds from which the next crisis will spring.

The overall profile of market conditions continues to feature: 1) hypervaluation on the measures we find best-correlated with actual subsequent S&P 500 total returns, coupled with 2) continued deterioration in our measures of market internals, which are the most reliable tools we’ve found to gauge the psychological inclination of investors toward speculation or risk-aversion.

Investment is about valuation. Speculation is about psychology. Both factors are unfavorable here. We’re observing the very early effects of risk-aversion in a hypervalued market. Based on the deterioration we’ve observed in our most reliable measures of market internals, investor preferences have subtly shifted toward risk-aversion, which opens up something of a trap-door.

In my view, the idea that higher risk means higher expected return is one of the most dangerous and misunderstood propositions in the financial markets. The reason it’s dangerous is that it ignores the central condition: “provided that one is choosing between portfolios that all maximize expected return per unit of risk.” Presently, the S&P 500 is both a high risk and a low expected return asset.

I expect the S&P 500 to lose approximately two-thirds of its value over the completion of this cycle. My impression is that future generations will look back on this moment and say "... and this is where they completely lost their minds." As I’ve regularly noted in recent months, our immediate outlook is essentially flat neutral for practical purposes, though we’re partial to a layer of tail-risk hedges.

Here we are, nearly three times the level at which I expect the S&P 500 to complete this cycle. Yet our immediate outlook remains neutral (though tail-risk hedges remain appropriate). It’s essential to distinguish between valuations, which have long-term implications, and market internals, which have implications for shorter segments of the market cycle.

The essential survival tactic for a hypervalued market, and its resolution ahead, is to recognize that market valuations can experience breathtaking departures from historical norms for extended segments of the market cycle, so long as shorter-term conditions contribute to speculative psychology rather than risk-averse psychology. Yet those departures matter enormously for long-term returns.

Delusions are often viewed as reflecting some deficiency in reasoning ability. The risk of thinking about delusions in this way is that it encourages the belief that logical, intelligent people are incapable of delusion. An examination of the history of financial markets suggests a different view.

Turbulence in market internals, in the face of record market highs, is often a symptom of increasing risk-aversion and skittishness among investors.

Last week, the uniformity of market internals shifted to an unfavorable condition. During the advancing half-cycle since 2009, zero interest rates encouraged speculation (and maintained favorable market internals) long after extreme overvalued, overbought, overbullish conditions emerged. But distinctions matter. Once the uniformity of market internals - the most reliable measure of speculation itself - is knocked away, those extremes are still likely to matter with a vengeance.

Encouraged by the novelty of zero-interest rates, not even the most extreme “overvalued, overbought, overbullish” conditions have been enough to derail the speculative inclinations of investors. Yet in every other way, this speculative episode is simply a more extreme variant of others that have come before it.

Current market valuations are consistent with negative expected returns for the S&P 500 over the coming 10-12 years, with a likely market loss of more than -60% in the interim.

Current market valuations are consistent with negative expected returns for the S&P 500 over the coming 10-12 years, with a likely market loss of more than -60% in the interim. The proposition that “lower interest rates justify higher valuations” has become a rather dangerous slogan, and is a distressingly incomplete statement that ignores the other half of the sentence: “provided that the stream of expected cash flows is held constant.”

The present moment of blissful delusion is remarkable to witness. Take it in. A few words and updated charts will do.

So the mindset, I think, goes something like this. Yes, market valuations are elevated, but, you know, low interest rates justify higher valuations. Besides, there’s really no alternative to stocks because you’ll get what, 1% annually in cash? Look at how the market has done in recent years. There’s no comparison.

At the October 2002 market low, the S&P 500 stood -49.2% below its March 2000 peak (-48.0% including dividend income), with the Nasdaq 100 having lost more than -82.8% from its high, on the basis of both price and total return. The loss wiped out the entire total return of the S&P 500, in excess of Treasury bills, all the way back to May 1996.

The main contributors to the illusion of permanent prosperity have been decidedly cyclical factors. Investors presently appear to be taking past investment returns and economic growth at face value, without considering their underlying drivers at all. My impression is that while the U.S. may very well encounter credit strains or other economic dislocations in the coming years...

Current extremes present what I view as one of the three most important opportunities in history to defend capital. My sense is that many investors will squander this opportunity until yet another bubble implodes.

The belief that Fed-induced speculation creates “wealth” is a conceit that rests on the delusion that “wealth” is embodied in the price of an asset, rather than the stream of cash flows it delivers over time.

Within a small number of years, investors are likely to discover that they have allowed their assumptions about growth in U.S. GDP, corporate revenues, earnings, and their own investment returns to become radically misaligned with reality, and that Wall Street’s justifications for the present, offensive level of equity market valuations are illusory. Based on outcomes that have systematically followed prior valuation extremes, the accompanying adjustment in expectations is likely to be associated with one of the most violent market declines in U.S. history, even if interest rates remain persistently depressed.

We extract signals about the preferences of investors toward speculation or risk-aversion based on the joint and sometimes subtle behavior of numerous markets and securities, so our inferences don't map to any short list of indicators. Still, internal dispersion is becoming apparent in measures that are increasingly obvious.

In my view (supported by a century of market cycles), investors are vastly underestimating the prospects for market losses over the completion of this cycle, are overestimating the availability of “safe” stocks or sectors that might avoid the damage, and are overestimating both the likelihood and the need for some recognizable “catalyst” to emerge before severe market losses unfold.

At the height of the technology bubble, the median of the most reliable market valuation measures we follow (those most strongly correlated with actual subsequent S&P 500 total returns) briefly reached an apex 178% above historical norms that had been regularly approached or breached over the completion of every market cycle in history.

Last week, the S&P 500 price/revenue ratio reached the highest level in history, outside of the single week of March 24, 2000 that represented the peak of the tech bubble.

What’s often missed in the “low interest rates justify higher valuations” argument is that this proposition assumes that future cash flows and growth rates are held constant.

Fully 1.4% of the 2.0% average annual real GDP growth observed since the beginning of 2010 has been driven by growth in civilian employment. As slack labor capacity has slowly been reduced, the unemployment rate has dropped from 10% to just 4.4%. That jig is up.

We are at the far edge of a monumental mesa here, but speculators are ignoring the cliff, assuming that they are on a permanently high plateau. The unfortunate aspect of these mesas and valleys is that they encourage backward-looking investors to believe that projected returns based on “old valuation measures” are no longer relevant, precisely when valuations are most informative about future returns.

Put simply, with market internals unfavorable and interest rates off the zero bound, the two main supports that made the half-cycle since 2009 “different” have already been kicked away.

The Fed does not have to make guesses about exactly what is required to normalize its balance sheet, except to the extent that it ignores a century of evidence.

The characteristic feature of a bubble is that the long-term return implied by discounted cash flows becomes detached from the higher, temporarily self-reinforcing return that is imagined by investors. As a result, the bubble component accounts for an increasingly large proportion of the total price, and becomes progressively vulnerable to collapse. It is in this precise sense that the current speculative episode can be characterized as a bubble, just as I (and Modigliani) characterized the bubble that ended in 2000.

Overall, my impression remains that the market is in the process of tracing out the blowoff finale of the third speculative financial bubble since 2000. Still, as is true for the market cycle as a whole, the broad outline of this top formation is likely to be shaped by three factors: 1) valuations, which primarily affect total market returns over a 10-12 year horizon, as well as the magnitude of potential losses over the completion of the market cycle; 2) the uniformity or divergence of market internals across a broad range of stocks and security-types, which remains the most reliable measure we’ve identified of the psychological preference of investors toward speculation or risk-aversion (when investors are inclined to speculate, they tend to be indiscriminate about it); and 3) overextended market action highlighting extremes of speculation or fear - in the advancing portion of the market cycle, these are best identified by syndromes of overvalued, overbought, overbullish conditions.

It’s precisely the failure of valuations to matter over shorter segments of the market cycle that regularly convinces investors that valuations don’t matter at all

My friend Mark Hulbert once had a philosophy professor at Oxford, who distinguished two ways of being wrong: “You can be just plain wrong, or you can be wrong in an interesting way.” In the latter case, Mark explained, correcting the wrong reveals a lot about the underlying truth.

When investors pay high P/E multiples on earnings that already reflect cyclically-elevated profit margins, they pay twice for their investment.

Every episode in history has its own wrinkles. But investors should not use some “new era” argument to dismiss the central principles of investing, as a substitute for carefully quantifying the impact of those wrinkles. Unfortunately, because investors get caught up in concepts, they come to a point in every speculative episode where they ignore the central principles of investing altogether.

Despite extreme valuations, investors’ fear of missing out is looking increasingly desperate. In market cycles across history, that has been an unfortunate impulse.

One way to use information on stock valuations and interest rates in a systematic way is to estimate the break-even level of valuation that would have to exist at given points in the future, in order for stocks to outperform or underperform bonds over various horizons. Investors presently face a dismal menu of expected returns regardless of their choice. Indeed, in order for expected S&P 500 total returns to outperform even the lowly return on Treasury bonds in the years ahead, investors now require market valuations to remain above historical norms for the next 22 years.The good news is that this menu is likely to improve substantially over the completion of the current market cycle. The problem is that current valuation extremes present a hostile combination of weak prospective return and steep risk.

One of the benefits of historically-informed investing is that it allows various investment perspectives to be evaluated from the standpoint of evidence rather than verbal argument. That’s particularly important during periods like today, when much of financial commentary on Wall Street can be filed into a folder labeled “it’s hard to argue with your logic, if only your facts were actually true.”

Put simply, investors are in an echo chamber here, where their optimism about economic outcomes is largely driven by optimism about the stock market, and optimism about the stock market is driven by optimism about economic outcomes. Given the deterioration in correlations between “soft” survey-based economic measures and subsequent economic and financial outcomes, investors should be placing a premium on measures that are reliably informative. On that front, hard economic data, labor force constraints, factors influencing productivity (particularly gross domestic investment and the position of the current account balance in the economic cycle), reliable valuation measures, and market internals should be high on that list.

Imagine driving a car moving down the road at 20 miles an hour. You hold a rope out the window. At the other end of that rope is a skateboard. If the skateboard is behind the car, yanking the rope pulls the skateboard forward, so the skateboard might temporarily speed ahead until it gets way ahead of the car and the rope tightens again.

Over the completion of the current market cycle, we estimate that roughly half of U.S. equity market capitalization - $17 trillion in paper wealth - will simply vanish. Nobody will “get” that wealth. It will simply disappear, like a game of musical chairs where players think they've won by finding chairs as the music stops, and suddenly feel them dissolving as if they had never existed in the first place.

Presently, based on the most historically reliable valuation measures we identify, we expect annual total returns for the S&P 500 averaging just 0.6% over the coming 12-year period; a prospective return that we expect will not only underperform bonds over this horizon, but even the lowly yields available on risk-free T-bills. 

During the later part of the roaring 20’s, Irving Berlin wrote “Blue Skies,” which captured some of the optimism of the era that preceded the Great Depression. Unfortunately, untethered optimism is not the friend of investors, particularly when they have already committed their assets to that optimism, and have driven valuations to speculative extremes.

"The issue is no longer whether the current market resembles those preceding the 1929, 1969-70, 1973-74, and 1987 crashes. The issue is only - are conditions like October of 1929, or more like April? Like October of 1987, or more like July?

As Benjamin Graham observed decades ago, "Speculators often prosper through ignorance; it is a cliche that in a roaring bull market, knowledge is superfluous and experience is a handicap. But the typical experience of the speculator is one of temporary profit and ultimate loss."

If there’s any point in U.S. stock market history, next to the market peaks of 1929 and 2000, that has deserved a time-stamp of speculative euphoria that will be bewildering in hindsight, now is that moment.