  The present paper describes a practical example in which the probability
distribution of the prices of a stock market blue chip is calculated as the
wave function of a quantum particle confined in a potential well. This model
may naturally explain the operation of several empirical rules used by
technical analysts. Models based on the movement of a Brownian particle do not
account for fundamental aspects of financial markets. This is due to the fact
that the Brownian particle is a classical particle, while stock market prices
behave more like quantum particles. When a classical particle meets an obstacle
or a potential barrier, it may either bounce or overcome the obstacle, yet not
both at a time. Only a quantum particle can simultaneously reflect and transmit
itself on a potential barrier. This is precisely what prices in a stock market
imitate when they find a resistance level: they partially bounce against and
partially overcome it. This can only be explained by admitting that prices
behave as quantum rather than as classic particles. The proposed quantum model
finds natural justification not only for the aforementioned facts but also for
other empirically well-known facts such as sudden changes in volatility,
non-Gaussian distribution in prices, among others.
