To Sum Up
Investment is most intelligent when it is most businesslike. It is amazing to see how many capable businessmen try to operate in Wall Street with complete disregard of all the sound principles through which they have gained success in their own undertakings.
Yet every corporate security may best be viewed, in the first instance, as an ownership interest in, or a claim against, a specific business enterprise. And if a person sets out to make profits from security purchases and sales, he is embarking on a business venture of his own, which must be run in accordance with accepted business principles if it is to have a chance of success.
The first and most obvious of these principles is, “Know what you are doing—know your business.” For the investor this means: Do not try to make “business profits” out of securities—that is, returns in excess of normal interest and dividend income—unless you know as much about security values as you would need to know about the value of merchandise that you proposed to manufacture or deal in.
A second business principle: “Do not let anyone else run your business, unless (1) you can supervise his performance with adequate care and comprehension or (2) you have unusually strong reasons for placing implicit confidence in his integrity and ability.” For the investor this rule should determine the conditions under which he will permit someone else to decide what is done with his money.
A third business principle: “Do not enter upon an operation— that is, manufacturing or trading in an item—unless a reliable calculation shows that it has a fair chance to yield a reasonable profit. In particular, keep away from ventures in which you have little to gain and much to lose.” For the enterprising investor this means that his operations for profit should be based not on optimism but on arithmetic. For every investor it means that when he limits his return to a small figure—as formerly, at least, in a conventional bond or preferred stock—he must demand convincing evidence that he is not risking a substantial part of his principal.
A fourth business rule is more positive: “Have the courage of your knowledge and experience. If you have formed a conclusion from the facts and if you know your judgment is sound, act on it—even though others may hesitate or differ.” (You are neither right nor wrong because the crowd disagrees with you. You are right because your data and reasoning are right.) Similarly, in the world of securities, courage becomes the supreme virtue after adequate knowledge and a tested judgment are at hand.
Fortunately for the typical investor, it is by no means necessary for his success that he bring these qualities to bear upon his program—provided he limits his ambition to his capacity and confines his activities within the safe and narrow path of standard, defensive investment. To achieve satisfactory investment results is easier than most people realize; to achieve superior results is harder than it looks.
Ref: The Intelligent Investor by Benjamin Graham