The key to investing is not assessing how much an industry is going to affect society, or how much it will grow, but rather determining the competitive advantage of any given company and, above all, the durability of that advantage.
Warren BuffettIt is obvious that the performance of a stock last year or last month is no reason, per se, to either own it or to not own it now. It is obvious that an inability to "get even" in a security that has declined is of no importance. It is obvious that the inner warm glow that results from having held a winner last year is of no importance in making a decision as to whether it belongs in an optimum portfolio this year.
Warren Buffett