Investment behavior is traditionally investigated with the assumption that risky investment is on average advantageous. However, this may not always be the case. In this paper, we experimentally studied investment choices made by students and financial professionals underfavorable and unfavorable market conditions in a multi-round investment game. In particular, the probability of winning was set so that investment in one condition was advantageous, and in onecondition was disadvantageous.To investigate who is more likely to adapt their investment behaviors to the changing market conditions, we also measured personality and self-efficacy. We expected that investment behavior in changing markets could be predicted by a combination of experience (students,professionals), personality (anxiety, optimism, impulsivity, and Openness to Experience), and self-efficacy (belief in one’s ability to make good decisions in an investment task).Results indicate that professionals do not significantly differ from students in their decisions.Personality and self-efficacy both predicted investment behavior. In particular, we found that optimism and anxiety were a liability in unfavorable markets, leading to unreasonable levels of risk. Impulsivity was a liability in both favorable and unfavorable markets, leading to high risk on unfavorable markets, and low risk in favorable markets. Openness to experience was an asset in unfavorable markets, leading to adjusted risk taking. Finally, self-efficacy was generally related to higher levels of risk.