The great personal fortunes in the country weren't built on a portfolio of fifty companies. They were built by someone who identified one wonderful business. With each investment you make, you should have the courage and the conviction to place at least 10% of your net worth in that stock.
There is no question that an important service is provided to investors by investment companies, investment advisors, trust departments, etc. This service revolves around the attainment of adequate diversification, the preservation of a long-term outlook, the ease of handling investment decisions and mechanics, and most importantly, the avoidance of the patently inferior investment techniques which seem to entice some individuals.
Investors should be skeptical of history-based models. Constructed by a nerdy-sounding priesthood using esoteric terms such as beta, gamma, sigma and the like, these models tend to look impressive. Too often, though, investors forget to examine the assumptions behind the models. Beware of geeks bearing formulas.
Ben's Mr. Market allegory may seem out-of-date in today's investment world, in which most professionals and academicians talk of efficient markets, dynamic hedging and betas. Their interest in such matters is understandable, since techniques shrouded in mystery clearly have value to the purveyor of investment advice. After all, what witch doctor has ever achieved fame and fortune by simply advising 'Take two aspirins'?
Observing that the market was FREQUENTLY efficient, EMT Adherents went on to conclude incorrectly that it was ALWAYS efficient. The difference between these propositions is night and day.
In that, we agreed with Andrew Carnegie, who said that huge fortunes that flow in large part from society should in large part be returned to society. In my case, the ability to allocate capital would have had little utility unless I lived in a rich, populous country in which enormous quantities of marketable securities were traded and were sometimes ridiculously mispriced. And fortunately for me, that describes the U.S. in the second half of the last century.