From his 1999 Letter to Shareholders:
We made few portfolio changes in 1999. As I mentioned earlier, several of the companies in which we have large investments had disappointing business results last year. Nevertheless, we believe these companies have important competitive advantages that will endure over time. This attribute, which makes for good long-term investment results, is one Charlie and I occasionally believe we can identify. More often, however, we can't -- not at least with a high degree of conviction. This explains, by the way, why we don't own stocks of tech companies, even though we share the general view that our society will be transformed by their products and services. Our problem -- which we can't solve by studying up -- is that we have no insights into which participants in the tech field possess a truly durable competitive advantage.
Our lack of tech insights, we should add, does not distress us. After all, there are a great many business areas in which Charlie and I have no special capital-allocation expertise. For instance, we bring nothing to the table when it comes to evaluating patents, manufacturing processes or geological prospects. So we simply don't get into judgments in those fields.
If we have a strength, it is in recognizing when we are operating well within our circle of competence and when we are approaching the perimeter. Predicting the long-term economics of companies that operate in fast-changing industries is simply far beyond our perimeter. If others claim predictive skill in those industries -- and seem to have their claims validated by the behavior of the stock market -- we neither envy nor emulate them. Instead, we just stick with what we understand. If we stray, we will have done so inadvertently, not because we got restless and substituted hope for rationality. Fortunately, it's almost certain there will be opportunities from time to time for Berkshire to do well within the circle we've staked out.
Right now, the prices of the fine businesses we already own are just not that attractive. In other words, we feel much better about the businesses than their stocks. That's why we haven't added to our present holdings. Nevertheless, we haven't yet scaled back our portfolio in a major way: If the choice is between a questionable business at a comfortable price or a comfortable business at a questionable price, we much prefer the latter. What really gets our attention, however, is a comfortable business at a comfortable price.