Awarded by two Nobel Prize winners in economics, behavioral finance proponents claim considerable consequences of behavioral biases on the investment policies of stock market players. By administering a questionnaire, the main purpose of the study is to empirically prove the relationship between the biases in our study (Overconfidence, Herding, loss aversion, disposition effect, anchoring, over-reaction to information and under-reaction to information) and their behavioral impact on the rationality of the decision-making process. Structural Equation Modeling (SEM), adopting the Partial Least Squares (PLS) approach, using Smart PLS 3.0 software, was conducted on the empirical data collected from a panel of financial professionals in the Moroccan stock market. Our results confirm the assumptions made beforehand and testify that these behavioral biases have a significant negative influence on the rationality of decision making process of the Moroccan portfolio managers.