  The future value of a security is described as a random variable.
Distribution of this random variable is the formal image of risk uncertainty.
On the other side, any present value is defined as a value equivalent to the
given future value. This equivalence relationship is a subjective. Thus
follows, that present value is described as a fuzzy number, which is depend on
the investor's susceptibility to behavioural factors. All above reasons imply,
that return rate is given as a fuzzy probabilistic set. The basic properties of
such image of return rate are studied. At the last the set of effective
securities is distinguished as a fuzzy set.
