The Disposition Effect is a concept that refers to disposition to sell winners too early and ride losers too long. Using data from institutional investors and mutual funds in the United States between 1980 and 2014, a measure of the Disposition Effect for each action it is proposed. It is evidence that the majority of the shares present Dispositio Effect and also that this phenomenon has a directly relationship with stock returns giving an empirical support that a full behavioral concept is influencing the formation of prices.