This article argues that intuition is a crucial component of professional competence, and provides empirical evidence to support this claim. It was found that in most cases intuitive predictions of stock market development are better than rationally justified ones and that experts predict more precisely than novices on a descriptive data level. The discussion links these findings to the literature about expertise and intuition. Research on professional expertise theoretically indicates intuition as a crucial component of that expertise. This article focuses on the exercise of intuition in the domain of investment. Stock market investment decisions rely on forecasts of market development. As complete information is not available, entirely rational decisions cannot be made, and it becomes necessary to rely on intuition. An overview of theories on intuition are presented followed by discussion of an empirical study in which 32 persons of varying experience in the stock market used intuition as well as rational justifications to predict stock rates.