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Irrational Exuberance by Robert J. Shiller
An excerpt from Irrational Exuberance by Robert J. Shiller (Princeton Univ. Press, 2000).

· From the Preface

... Why did the U.S. stock market reach such high levels by the turn of the millennium? What changed to cause the market to become so highly priced? What do these changes mean for the market outlook in the opening decades of the new millennium? Are powerful fundamental factors at work to keep the market as high as it is now or to push it even higher, even if there is a downward correction? Or is the market high only because of some "irrational exuberance" -- wishful thinking on the part of investors that blinds us to the truth of our situation?

The answers to these questions are critically important to private and public interests alike. How we value the stock market now and in the future influences major economic and social policy decisions that affect not only investors but also society at large, even the world. If we exaggerate the present and future value of the stock market, then as a society we may invest too much in business startups and expansions, and too little in infrastructure, education, and other forms of human capital. If we think the market is worth more than it really is, we may become complacent in funding our pension plans, in maintaining our savings rate, in legislating an improved Social Security system, and in providing other forms of social insurance. We might also lose the opportunity to use our expanding financial technology to devise new solutions to the genuine risks -- to our homes, cities, and livelihoods -- that we face. ...

· From Chapter One:
The Stock Market Level in Historical Perspective

When Alan Greenspan, chairman of the Federal Reserve Board in Washington, used the term "irrational exuberance" to describe the behavior of stock market investors in an otherwise staid speech on December 5, 1996, the world fixated on those words. Stock markets dropped precipitously. In Japan, the Nikkei index dropped 3.2%; in Hong Kong, the Hang Seng dropped 2.9%; and in Germany, the DAX dropped 4%. In London, the FT-SE 100 index was down 4% at one point during the day, and in the United States, the Dow Jones Industrial Average was down 2.3% near the beginning of trading. The words "irrational exuberance" quickly became Greenspan's most famous quote -- a catch phrase for everyone who follows the market.

Why did the world react so strongly to these words? One view is that they were considered simply as evidence that the Federal Reserve would soon tighten monetary policy, and the world was merely reacting to revised forecasts of the Board's likely actions. But that cannot explain why the public still remembers irrational exuberance so well years later. I believe that the reaction to these words reflects the public's concern that the markets may indeed have been bid up to unusually high and unsustainable levels under the influence of market psychology. Greenspan's words suggest the possibility that the stock market will drop -- or at least become a less promising investment.



Robert Shiller is the Stanley B. Resor Professor of Economics at Yale University and the author of Irrational Exuberance (2000), which received the Commonfund Prize, and Market Volatility (1989), recipient of the 1996 Paul A. Samuelson Award. The publication of Irrational Exuberance coincided with the peak of the Nasdaq index in March of 2000.

History certainly gives credence to this concern. In the balance of this chapter, we study the historical record. Although the discussion in this chapter gets pretty detailed, I urge you to follow its thread, for the details place today's situation in a useful, and quite revealing, context.

Market Heights

By historical standards, the U.S. stock market has soared to extremely high levels in recent years. These results have created a sense among the investing public that such high valuations, and even higher ones, will be maintained in the foreseeable future. Yet if the history of high market valuations is any guide, the public may be very disappointed with the performance of the stock market in coming years.

An unprecedented increase just before the start of the new millennium has brought the market to this great height. The Dow Jones Industrial Average (from here on, the Dow for short) stood at around 3,600 in early 1994. By 1999, it had passed 11,000, more than tripling in five years, a total increase in stock market prices of over 200%. At the start of 2000, the Dow passed 11,700.

However, over the same period, basic economic indicators did not come close to tripling. U.S. personal income and gross domestic product rose less than 30%, and almost half of this increase was due to inflation. Corporate profits rose less than 60%, and that from a temporary recession-depressed base. Viewed in the light of these figures, the stock price increase appears unwarranted and, certainly by historical standards, unlikely to persist.

Large stock price increases have occurred in many other countries at the same time. In Europe, between 1994 and 1999 the stock market valuations of France, Germany, Italy, Spain, and the United Kingdom roughly doubled. The stock market valuations of Canada, too, just about doubled, and those of Australia increased by half.

In the course of 1999, stock markets in Asia (Hong Kong, Indonesia, Japan, Malaysia, Singapore, and South Korea) and Latin America (Brazil, Chile, and Mexico) have made spectacular gains. But no other country of comparable size has had so large an increase since 1994 as that seen in the United States.

Price increases in single-family homes have also occurred over the same time but significant increases have occurred in only a few cities. Between 1994 and 1999 the total average real price increase of homes in ten major U.S. cities was only 9%. These price increases are tiny relative to the increase in the U.S. stock market.

The extraordinary recent levels of U.S. stock prices, and associated expectations that these levels will be sustained or surpassed in the near future, present some important questions. We need to know whether the current period of high stock market pricing is like the other historical periods of high pricing, that is, whether it will be followed by poor or negative performance in coming years. We need to know confidently whether the increase that brought us here is indeed a "speculative bubble" -- an unsustainable increase in prices brought on by investors' buying behavior rather than by genuine, fundamental information about value. In short, we need to know if the value investors have imputed to the market is not really there, so that we can readjust our planning and thinking.

A Look at the Data

Figure 1.1 shows, for the United States, the monthly real (corrected for inflation using the Consumer Price Index) Standard and Poor's (S&P) Composite Stock Price Index from January 1871 through January 2000 (upper curve), along with the corresponding series of real S&P Composite earnings (lower curve) for the same years. This figure allows us to get a truly long-term perspective on the U.S. stock market's recent levels. We can see how differently the market has behaved recently as compared with the past. We see that the market has been heading up fairly uniformly ever since it bottomed out in July 1982. It is clearly the most dramatic bull market in U.S. history. The spiking of prices in the years 1992 through 2000 has been most remarkable: the price index looks like a rocket taking off through the top of the chart! This largest stock market boom ever may be referred to as the "millennium boom."

figure 1.1

Yet this dramatic increase in prices since 1982 is not matched in real earnings growth. Looking at the figure, no such spike in earnings growth occurs in recent years. Earnings in fact seem to be oscillating around a slow, steady growth path that has persisted for over a century.

No price action quite like this has ever happened before in U.S. stock market history. There was of course the famous stock run-up of the 1920s, culminating in the 1929 crash. Figure 1.1 reveals this boom as a cusp-shaped price pattern for those years. If one corrects for the market's smaller scale then, one recognizes that this episode in the 1920s does resemble somewhat the recent stock market increase, but it is the only historical episode that comes even close to being comparable to the present boom.

There was also a dramatic run-up in the late 1950s and early 1960s, culminating in a flat period for half a decade that was followed by the 1973-74 stock market debacle. But the price increase during this boom was certainly less dramatic than today's.

Price Relative to Earnings

Part of the explanation for the remarkable price behavior between 1990 and 2000 may have to do with somewhat unusual earnings. Many observers have remarked that earnings growth in the five-year period ending in 1997 was extraordinary: real S&P Composite earnings more than doubled over this interval, and such a rapid five-year growth of real earnings has not occurred for nearly half a century. But 1992 marked the end of a recession during which earnings were temporarily depressed. Similar increases in earnings growth have happened before following periods of depressed earnings from recession or depression. In fact, there was more than a quadrupling of real earnings from 1921 to 1926 as the economy emerged from the severe recession of 1921 into the prosperous Roaring Twenties. Real earnings doubled during five-year periods following the depression of the 1890s, the Great Depression of the 1930s, and World War II.

Figure 1.2 shows the price-earnings ratio, that is, the real (inflation-corrected) S&P Composite Index divided by the ten-year moving average real earnings on the index. The dates shown are monthly, January 1881 to January 2000. The price-earnings ratio is a measure of how expensive the market is relative to an objective measure of the ability of corporations to earn profits. I use the ten-year average of real earnings for the denominator, along lines proposed by Benjamin Graham and David Dodd in 1934. The ten-year average smooths out such events as the temporary burst of earnings during World War I, the temporary decline in earnings during World War II, or the frequent boosts and declines that we see due to the business cycle. Note again that there is an enormous spike after 1997, when the ratio rises until it hits 44.3 by January 2000. Price-earnings ratios by this measure have never been so high. The closest parallel is September 1929, when the ratio hit 32.6.

figure 1.1

In the latest data on earnings, earnings are quite high in comparison with the Graham and Dodd measure of long-run earnings, but nothing here is startlingly out of the ordinary. What is extraordinary today is the behavior of price (as also seen in Figure 1.1), not earnings.

There have been three other times when the price-earnings ratio as shown in Figure 1.2 attained high values, though never as high as the 2000 value. ...

Worries about Irrational Exuberance

The news media have tired of describing the high levels of the market, and discussion of it is usually omitted from considerations of market outlook. And yet, deep down, people know that the market is highly priced, and they are uncomfortable about this fact.

Most people I meet, from all walks of life, are puzzled over the apparently high levels of the stock market. We are unsure whether the market levels make any sense, or whether they are indeed the result of some human tendency that might be called irrational exuberance. We are unsure whether the high levels of the stock market might reflect unjustified optimism, an optimism that might pervade our thinking and affect many of our life decisions. We are unsure what to make of any sudden market correction, wondering if the previous market psychology will return.

Even Alan Greenspan seems unsure. He made his "irrational exuberance" speech two days after I had testified before him and the Federal Reserve Board that market levels were irrational, but a mere seven months later he reportedly took an optimistic "new era" position on the economy and the stock market. In fact, Greenspan has always been very cautious in his public statements, and he has not committed himself to either view. A modern version of the prophets who spoke in riddles, Greenspan likes to pose questions rather than make pronouncements. In the public exegesis of his remarks, it is often forgotten that, when it comes to such questions, even he does not know the answers.


(c) 2000 by Robert J. Shiller All rights reserved.

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