This chapter’s review of the Internet and housing bubbles seems inconsistent with the view that our stock and real estate markets are rational and efficient. The lesson, however, is not that markets occasionally can be irrational and that we should therefore abandon the firm-foundation theory of the pricing of financial assets. Rather, the clear conclusion is that, in every case, the market did correct itself. The market eventually corrects any irrationality—albeit in its own slow, inexorable fashion. Anomalies can crop up, markets can get irrationally optimistic, and often they attract unwary investors. But, eventually, true value is recognized by the market, and this is the main lesson investors must heed.
I am also persuaded by the wisdom of Benjamin Graham, author of Security Analysis, who wrote that in the final analysis the stock market is not a voting mechanism but a weighing mechanism. Valuation metrics have not changed. Eventually, every stock can only be worth the present value of its cash flow. In the final analysis, true value will win out.

By telling this story, I do not mean to suggest that you attempt to cheat the government. But I do mean to suggest that you take advantage of every opportunity to make your savings tax-deductible and to let your savings and investments grow tax-free. For most people, there is no reason to pay any taxes on the earnings from the investments that you make to provide for your retirement. Almost all investors, except those who are super wealthy to begin with, can build up a substantial net worth in ways that ensure that nothing will be siphoned off by Uncle Sam. This exercise shows how you can legally stiff the tax collector.

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Our survey of historical bubbles makes clear that the bursting of bubbles has invariably been followed by severe disruptions in real economic activity. The fallout from asset-price bubbles has not been confined to speculators. Bubbles are particularly dangerous when they are associated with a credit boom and widespread increases in leverage both for consumers and for financial institutions.

Remember Murphy’s Law: What can go wrong will go wrong. And don’t forget O’Toole’s commentary: Murphy was an optimist. Bad things do happen to good people. Life is a risky proposition, and unexpected financial needs occur in everyone’s lifetime. The boiler tends to blow up just at the time that your family incurs whopping medical expenses. A job layoff happens just after your son has totaled the family car. That’s why every family needs a cash reserve as well as adequate insurance to cope with the catastrophes of life.

Investors should certainly be aware of new methods of portfolio construction. And high net worth investors might consider adding a multifactor smart beta offering or a risk-parity portfolio to the overall mix of their investments. Factor investing can potentially increase returns at the cost of assuming a somewhat different set of risk exposures than those of a standard broad-based index fund. And investors who are able to accept the added risks inherent in leverage might profitably add a risk-parity portfolio to their set of investments. Such offerings should only be considered, however, if they are low cost and if their potentially adverse tax effects can be offset in other parts of the overall portfolio. And I continue to believe that a broad-based total stock market index fund should be the core of everyone’s portfolio. Certainly, for investors who are starting to build an equity portfolio in planning for retirement, standard capitalization-weighted index funds are the appropriate first investments they should make.

Behavioral-finance theory also helps explain why many people refuse to join a 401(k) savings plan at work, even when their company matches their contributions. If one asks an employee who has become used to a particular level of take-home pay to increase his allocation to a retirement plan by one dollar, he will view the resulting deduction (even though it is less than a dollar because contributions to retirement plans are deductible from taxable income up to certain generous amounts) as a loss of current spending availability. Individuals weigh these losses much more heavily than gains. When this loss aversion is coupled with the difficulty of exhibiting self-control, the ease of procrastinating, and the ease of making no changes (status quo bias), it becomes, as psychologists teach us, perfectly understandable why people tend to save too little.

A random walk is one in which future steps or directions cannot be predicted on the basis of past history. When the term is applied to the stock market, it means that short-run changes in stock prices are unpredictable. Investment advisory services, earnings forecasts, and chart patterns are useless. On Wall Street, the term “random walk” is an obscenity. It is an epithet coined by the academic world and hurled insultingly at the professional soothsayers. Taken to its logical extreme, it means that a blindfolded monkey throwing darts at the stock listings could select a portfolio that would do as well as one selected by the experts.

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To the great relief of assistant professors who must publish or perish, there is still much debate within the academic community on risk measurement, and much more empirical testing needs to be done. Undoubtedly, there will yet be many improvements in the techniques of risk analysis, and the quantitative analysis of risk measurement is far from dead. My own guess is that future risk measures will be even more sophisticated—not less so. Nevertheless, we must be careful not to accept beta or any other measure as an easy way to assess risk and to predict future returns with any certainty. You should know about the best of the modern techniques of the new investment technology—they can be useful aids. But there is never going to be a handsome genie who will appear and solve all our investment problems.

With these broad time periods set, let us now look at how the determinants of returns developed during those eras and look especially at what might have been responsible for changes in valuation relationships and in interest rates. Recall that stock returns are determined by (1) the initial dividend yield at which the stocks were purchased, (2) the growth rate of earnings, and (3) changes in valuation in terms of price-earnings (or price-dividend) ratios. And bond returns are determined by (1) the initial yield to maturity at which the bonds were purchased and (2) changes in interest rates (yields) and therefore in bond prices for bond investors who do not hold to maturity.

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Technology will ultimately greatly improve the intentional payments system. And there will always be advantages to holding an asset that is anonymous and transportable without a physical trace. But the lessons of history are immutable. Speculative bubbles will persist. But they ultimately lead most of their participants to financial ruin. Even real technology revolutions do not guarantee benefits for investors.

History, in this instance, does teach a lesson: Although the castle-in-the-air theory can well explain such speculative binges, outguessing the reactions of a fickle crowd is a most dangerous game. “In crowds it is stupidity and not mother-wit that is accumulated,” Gustave Le Bon noted in his 1895 classic on crowd psychology. It would appear that not many have read the book. Skyrocketing markets that depend on purely psychic support have invariably succumbed to the financial law of gravitation. Unsustainable prices may persist for years, but eventually they reverse themselves. Such reversals come with the suddenness of an earthquake; and the bigger the binge, the greater the resulting hangover. Few of the reckless builders of castles in the air have been nimble enough to anticipate these reversals and to escape when everything came tumbling down.

There are, I believe, five factors that help explain why security analysts have such difficulty in predicting the future. These are (1) the influence of random events, (2) the production of dubious reported earnings through “creative” accounting procedures, (3) errors made by the analysts themselves, (4) the loss of the best analysts to the sales desk or to portfolio management, and (5) the conflicts of interest facing securities analysts at firms with large investment banking operations. Each factor deserves some discussion.

As I’ve already pointed out, some ready assets are necessary for pending expenses, such as college tuition, possible emergencies, or even psychological support. Thus, you have a real dilemma. You know that if you keep your money in a savings bank and get, say, 2 percent interest in a year in which the inflation rate exceeds 2 percent, you will lose real purchasing power. In fact, the situation is even worse because the interest you get is subject to regular income taxes. Moreover, short-term interest rates were abnormally low during the 2010s. So what’s a small saver to do? There are several short-term investments that are likely to help provide the best rate of return, although no very good alternatives exist when interest rates are very low.

The strong form of the EMH is obviously an overstatement. It does not admit the possibility of gaining from inside information. Nathan Rothschild made millions in the market when his carrier pigeons brought him the first news of Wellington’s victory at Waterloo before other traders were aware of the victory. But today, the information superhighway carries news far more swiftly than carrier pigeons. And Regulation FD (Fair Disclosure) requires companies to make prompt public announcements of any material news items that may affect the price of their stock. Moreover, insiders who do profit from trading on the basis of nonpublic information are breaking the law.

The castle-in-the-air theory of investing concentrates on psychic values. John Maynard Keynes, a famous economist and successful investor, enunciated the theory most lucidly in 1936. It was his opinion that professional investors prefer to devote their energies not to estimating intrinsic values, but rather to analyzing how the crowd of investors is likely to behave in the future and how during periods of optimism they tend to build their hopes into castles in the air. The successful investor tries to beat the gun by estimating what investment situations are most susceptible to public castle-building and then buying before the crowd.