BURTON G. MALKIEL

A Random Walk Down Wall Street

All investment returns — whether from common stocks or exceptional diamonds — are dependent, to varying degrees, on future events. That's what makes the fascination of investing: It's a gamble whose success depends on an ability to predict the future. Traditionally, the pros in the investment community have used one of two approaches to asset valuation: the firm-foundation theory or the castle-in-the-air theory. Millions of dollars have been gained and lost on these theories. To add to the drama, they appear to be mutually exclusive. An understanding of these two approaches is essential if you are to make sensible investment decisions. It is also a prerequisite for keeping you safe from serious blunders. During the 1970s, a third theory, born in academia and named the new investment technology, became popular in "the Street." Later in the book, I will describe that theory and its application to investment analysis.

The Castle-in-the-Air Theory

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.

According to Keynes, the firm-foundation theory involves too much work and is of doubtful value. Keynes practiced what he preached. While London's financial men toiled many weary hours in crowded offices, he played the market from his bed for half an hour each morning. This leisurely method of investing earned him several million pounds for his account and a tenfold increase in the market value of the endowment of his college, King's College, Cambridge.

In the depression years in which Keynes gained his fame, most people concentrated on his ideas for stimulating the economy. It was hard for anyone to build castles in the air or to dream that others would. Nevertheless, in his book The General Theory of Employment, Interest and Money, he devoted an entire chapter to the stock market and to the importance of investor expectations.

With regard to stocks, Keynes noted that no one knows for sure what will influence future earnings prospects and dividend payments. As a result, Keynes said, most persons are "largely concerned, not with making superior long-term forecasts of the probable yield of an investment over its whole life, but with foreseeing changes in the conventional basis of valuation a short time ahead of the general public." Keynes, in other words, applied psychological principles rather than financial evaluation to the study of the stock market. He wrote, "It is not sensible to pay 25 for an investment of which you believe the prospective yield to justify a value of 30, if you also believe that the market will value it at 20 three months hence."

Keynes described the playing of the stock market in terms readily understandable by his fellow Englishmen: It is analogous to entering a newspaper beauty-judging contest in which one must select the six prettiest faces out of a hundred photographs, with the prize going to the person whose selections most nearly conform to those of the group as a whole.

The smart player recognizes that personal criteria of beauty are irrelevant in determining the contest winner. A better strategy is to select those faces the other players are likely to fancy. This logic tends to snowball. After all, the other participants are likely to play the game with at least as keen a perception. Thus, the optimal strategy is not to pick those faces the player thinks are prettiest, or those the other players are likely to fancy, but rather to predict what the average opinion is likely to be about what the average opinion will be, or to proceed even further along this sequence. So much for British beauty contests.

The newspaper-contest analogy represents the ultimate form of the castle-in-the-air theory of price determination. An investment is worth a certain price to a buyer because she expects to sell it to someone else at a higher price. The investment, in other words, holds itself up by its own bootstraps. The new buyer in turn anticipates that future buyers will assign a still-higher value.

In this kind of world, there is a sucker born every minute — and he exists to buy your investments at a higher price than you paid for them. Any price will do as long as others may be willing to pay more. There is no reason, only mass psychology. All the smart investor has to do is to beat the gun — get in at the very beginning. This theory might less charitably be called the "greater fool" theory. It's perfectly all right to pay three times what something is worth as long as later on you can find some innocent to pay five times what it's worth.

The castle-in-the-air theory has many advocates, in both the financial and the academic communities. Keynes's newspaper contest is the same game played by "Adam Smith" in The Money Game. Mr. Smith also espouses the same view of stock price determination. On the academic side, so-called behavioral theories of the stock market, stressing crowd psychology, gained favor during the 1990s at leading economics departments and business schools across the developed world. Earlier, Oskar Morgenstern was a leading champion. The views he expressed in Theory of Games and Economic Behavior, of which he was co-author, have had a significant impact not only on economic theory but also on national security decisions and strategic corporate planning. In 1970 he co-authored another book, Predictability of Stock Market Prices, in which he and his colleague, Clive Granger, argued that the search for intrinsic value in stocks is a search for the will-o'-the-wisp. In an exchange economy the value of any asset depends on an actual or prospective transaction. Morgenstern believed that every investor should post the following Latin maxim above his desk:

How the Random Walk Is to Be Conducted

With this introduction out of the way, come join me for a random walk through the investment woods, with an ultimate stroll down Wall Street. My first task will be to acquaint you with the historical patterns of pricing and how they bear on the two theories of pricing investments. It was Santayana who warned that if we did not learn the lessons of the past we would be doomed to repeat the same errors. Therefore, in the pages to come I will describe some spectacular crazes — both long past and recently past. Some readers may pooh-pooh the mad public rush to buy tulip bulbs in seventeenth-century Holland and the eighteenth-century South Sea Bubble in England. But no one can disregard the new-issue mania of the early 1960s, the "Nifty Fifty" craze of the 1970s, or the biotechnology bubble of the 1980s. The incredible boom in Japanese land and stock prices and the equally spectacular crash of those prices in the early 1990s, as well as the "Internet craze" of the late 1990s, provide continual warnings that we are not immune from the errors of the past.

These more recent speculative "bubbles" all involved the savvy institutions and investment pros. All too many investors are lazy and careless — a terrifying combination when greed gets control of the market and everyone wants to cash in on the latest craze or fad.

Then I throw in my own two cents' worth of experience. Even in the midst of a period of speculation, I believe, it is possible to find a logical basis for security prices. At the end of Part One I present some rules that should be helpful in giving investors a sense of value and in protecting you from the horrible blunders made by many professional investment managers.