The Most Important Thing: Uncommon Sense for the Thoughtful Investor (Columbia Business School Publishing)

by Howard Marks

• Investors are right (and wrong) all the time for the “wrong reason.” Someone buys a stock because he or she expects a certain development; it doesn’t occur; the market takes the stock up anyway; the investor looks good (and invariably accepts credit). • The correctness of a decision can’t be judged from the outcome. Nevertheless, that’s how people assess it. A good decision is one that’s optimal at the time it’s made, when the future is by definition unknown. Thus, correct decisions are often unsuccessful, and vice versa. • Randomness alone can produce just about any outcome in the short run. In portfolios that are allowed to reflect them fully, market movements can easily swamp the skillfulness of the manager (or lack thereof). But certainly market movements cannot be credited to the manager (unless he or she is the rare market timer who’s capable of getting it right repeatedly). • For these reasons, investors often receive credit they don’t deserve. One good coup can be enough to build a reputation, but clearly a coup can arise out of randomness alone. Few of these “geniuses” are right more than once or twice in a row. • Thus, it’s essential to have a large number of observations—lots of years of data—before judging a given manager’s ability.