  The trade of a fixed stock can be regarded as the basic process that measures
its momentary price. The stock price is exactly known only at the time of sale
when the stock is between traders, that is, only in the case when the owner is
unknown. We show that the stock price can be better described by a function
indicating at any moment of time the probabilities for the possible values of
price if a transaction takes place. This more general description contains
partial information on the stock price, but it also contains partial
information on the stock owner. By following the analogy with quantum
mechanics, we assume that the time evolution of the function describing the
stock price can be described by a Schrodinger type equation.
