The purpose of this paper is to systematically profile investors personality traits to examine if, and how, those traits are associated with phenomena observed in financial markets. In particular, the paper looks at overconfidence and overreaction in an experimental foreign exchange market. The paper measures the personality of the subjects using the short form of the NEO-PIR instrument, the NEO-FFI developed by Costa and McRae (1992) which is based on Norman s (1963) Big Five personality constructs of negative emotion, extraversion, openness to experience, agreeableness and conscientiousness. The paper measures psychological gender using questions developed by Bem (1994). Preference for innovation and risk-taking propensity are measured using instruments developed by Jackson (1976). The paper then examines the behavior of the subject who traded interactively in real time in an interactive-simulated foreign exchange market where price discovery was instantaneous and pricing decisions were made instantaneously as items of news, determined by the researchers, were released. The paper demonstrates that personality traits are associated with overconfidence and overreaction in financial markets. The paper presents meta-analysis which facilitates the development of a posteriori theories of how particular traits affect investment; there are important roles for risk-taking propensity, negative emotion, extraversion, masculinity, preference for innovation and conscientiousness.