In the present study, we attempt to analyse and study (1) what sort of events will initiate a psychological instead of rational response from small investors, (2) the decision making process when they are emotional, and (3) the differences between their less-rational actions and normal ones. The primary objective is to investigate the factors, investing characteristics, and decision making processes that affect Hong Kong’s small investors who participate in derivatives markets. Informed by behavioural finance, we develop several hypotheses regarding the changes in the opinion and investment behaviour of small investors during global economic crisis. These hypotheses are then tested with the data collected from 524 small investors via a questionnaire survey. By doing so, we hope to contribute to the study of behavioural finance in the setting of an Asian financial centre, Hong Kong.