Using comprehensive data from the Finnish stock market, we assess the explanatory value of the three most commonly cited explanations for the disposition effect: prospect theory, belief in mean reversion, and escalation of commitment. In general, the results provide evidence for the presence of the disposition effect. More importantly, the effect appears to be significantly more pronounced when investors are personally responsible for the initial investment decision. This finding suggests that investor behavior is influenced above all by self-justificatory concerns, an interpretation that is consistent with the escalation of commitment-based explanation of the disposition effect. Copyright © 2011 John Wiley & Sons, Ltd.