Overconfidence Mediates How Perception of past Portfolio Returns Affects Investment Behaviors

ABSTRACT Investors’ perception of past portfolio returns predicts their investment behavior, but does this relationship mediate by overconfidence? Taking into account different aspects of overconfidence, this paper examines whether overconfidence manifested as illusion of control, miscalibration and better-than-average mediates the association between perception of past portfolio returns and investment behavior. In a survey study with individual and institutional investors from Malaysia, the results indicate that perception of higher past portfolio returns increases investors’ trading, percentage of risky share investment and the number of financial asset holding, through the mediating channel of better-than-average effect. While individual investors are influenced by this overconfidence mechanism, institutional investors are not sensitive. This finding has theoretical implication for overconfidence model, house money effect and naïve reinforcement learning. Practically, the results imply that individual investors should be careful about underlying overconfidence biases as it can lead to inefficient decisions.