Imagine that in some private business you own a small share that cost you $1,000. One of your partners, named Mr. Market, is very obliging indeed. Every day he tells you what he thinks your interest is worth and furthermore offers either to buy you out or to sell you an additional interest on that basis. Sometimes his idea of value appears plausible and justified by business developments and prospects as you know them. Often, on the other hand, Mr. Market lets his enthusiasm or his fears run away with him, and the value he proposes seems to you a little short of silly.
If you are a prudent investor or a sensible businessman, will you let Mr. Market's daily communication determine your view of the value of a $1,000 interest in the enterprise? Only in case you agree with him, or in case you want to trade with him. You may be happy to sell out to him when he quotes you a ridiculously high price, and equally happy to buy from him when his price is low. But the rest of the time you will be wiser to form your own ideas of the value of your holdings, based on full reports from the company about its operations and financial position.
The true investor is in that very position when he owns a listed common stock. He can take advantage of the daily market price or leave it alone, as dictated by his own judgment and inclination. He must take cognizance of important price movements, for otherwise his judgment will have nothing to work on. Conceivably, they may give him a warning signal which he will do well to heed-- this in plain English means that he is to sell his shares because the price has gone down, foreboding worse things to come. In our view such signals are misleading at least as often as they are helpful. Basically, price fluctuations have only one significant meaning for the true investor. They provide him with an opportunity to buy wisely when prices fall sharply and to sell wisely when they advance a great deal. At other times he will do better if he forgets about the stock market and pays attention to his dividend returns and to the operating results of his companies.
If your investment horizon is long-- at least 25 or 30 years-- there is only one sensible approach: Buy every month, automatically, and whenever else you can spare some money. The single best choice for this lifelong holding is a total stock-market index fund. Paradoxically, "you will be much more in control," explains neuroscientist Antonio Damasio, "if you realize how much you are not in control." By acknowledging your biological tendency to buy high and sell low, you can admit the need to dollar-cost average, rebalance, and sign an investment contract. By putting much of your portfolio on permanent autopilot, you can fight the prediction addiction, focus on your long-term financial goals, and tune out Mr. Market's mood swings.
Investing in Investment Funds
Financial scholars have been studying mutual-fund performance for at least a half century, and they are virtually unanimous on several points:
the average fund does not pick stocks well enough to overcome its costs of researching and trading them;
the higher a fund's expenses, the lower its returns;
the more frequently a fund trades its stocks, the less it tends to earn;
highly volatile funds, which bounce up and down more than average, are likely to stay volatile;
funds with high past returns are unlikely to remain winners for long.
What, then, should the intelligent investor do? First of all, recognize that an index fund-- which owns all the stocks in the market, all the time, without any pretense of being able to select the "best" and avoid the "worst"-- will beat most funds over the long run. As the years pass, the cost advantage of indexing will keep accruing relentlessly. Hold an index fund for 20 years or more, adding new money every month, and you are all but certain to outperform the vast majority of professional and individual investors alike. Late in his life, Graham praised index funds as the best choice for individual investors, as does Warren Buffett.
Margin of Safety as the Central Concept of Investment
Probably most speculators believe they have the odds in their favor when they take their chances, and therefore they may lay claim to a safety margin in their proceedings. Each one has the feeling that the time is propitious for his purchase, or that his skill is superior to the crowd's, or that his adviser or system is trustworthy. But such claims are unconvincing. They rest on subjective judgment, unsupported by any body of favorable evidence or any conclusive line of reasoning. We greatly doubt whether the man who stakes money on his view that the market is heading up or down can ever be said to be protected by a margin of safety in any useful sense of the phrase.
By contrast, the investor's concept of the margin of safety-- as developed earlier in this chapter-- rests upon simple and definite arithmetical reasoning from statistical data. We believe, also, that it is well supported by practical investment experience. There is no guarantee that this fundamental quantitative approach will continue to show favorable results under the unknown conditions of the future. But, equally, there is no valid reason for pessimism on this score. Thus, in sum, we say that to have a true investment there must be present a true margin of safety. And a true margin of safety is one that can be demonstrated by figures, by persuasive reasoning, and by reference to a body of actual experience.