Behavorial finance investigation is based on concepts of cognitive psychology decision theory. In addition, behavioral finance studies how real-life investors interpret and act on available information. Financial theories are dominated by efficient market theory assuming rational agents. he key assumption of financial models under this theory is the rational behavior of investors and other economic agents. Empirical observation demonstrates this assumption regularly is violated.Markets often are inefficient. Information disclosure is expensive, and accordingly is distributed asymmetrically. Heuristics may change the investors’ behavior and bias their decisions. Among biases are that each investment decision depends on our previous investment decisions: we are anchored by memory and experience and Bayesian approaches to the data are not of sufficient explanatory power to compensate for the remaining unknowns.