개인 투자자의 과도거래와 투자성과

The purpose of this study is to examine why individual investors do trade excessively. To accomplish that goal, the paper investigates the effects of different personalities of individual investors on trading behavior and thus investment performance. Barber and Odean (2000) used individual investor data to show that investors trade too frequently even though such frequent trading is costly, and thus harmful to their portfolios and overall wealth. Using similar data, Goetzmann and Kumar (2001) showed that the equity portfolios of individual investors are much less diversified than could be normally predicted by portfolio theory. Prior empirical studies on this behavioral investor topic have been conducted mainly on investors with discount brokerage accounts. The analysis on these characteristics, however, was limited to the information the database provides. Therefore, most of the studies thus far focused on observable variables, such as gender, age, family size and income, trading experience, and trading patterns. Our paper differs from previous studies in that we investigate excessive trading at the level of each individual and his or her particular investing behavior. The previous explanation for excessive trading behavior of investors was argued by Barber and Odean (2001), who indicated that overconfidence leads to excessive trading and the excessive trading is hazardous to investor wealth. The evidence to date for excessive trading behavior has been demonstrated by aggregating the data across all trades and traders to arrive at the mean effect for a representative investor in the market. In this paper, we argue that personalities of investors can lead to excessive trading behavior. In particular, we study the big-five personality traits, including neuroticism, extraversion, openness, agreeableness, and conscientiousness, all of which are traits that are commonly used in psychology studies. We also analyze individual confidence level to measure overconfidence and then examine whether overconfidence does lead to excessive trading behavior. Based on the sample of individual trading data collected from an Internet stockinvestment game company that provides real cash to qualified participants, the qualified investors for the real stock investment were selected from pseudo-trading competitions. We surveyed these sample investors to measure their confidence level, personality traits, and demographics. Also, we considered systematic risks measured by beta in determining an investor’s performance. The results from this empirical analysis can be summarized as follows: First, our analysis confirmed the findings of previous studies (Barber and Odean 2001, 2002) that indicated that overconfident individual investors, on average, exhibit the excessive trading behavior. Second, we found that overconfidence leads to excessive trading and excessive trading is harmful to wealth. However, we did find that investor gender, marital status, and trading experience have no explanatory power to produce excessive trading or investment performance. Finally, investors with more extraversion personalities tend to trade more frequently, a behavior that can lead to lower investment return than that experienced by other investors with lower extraversion trait. Our findings have important implications for policy makers as well as behavioral financial theorists. First, overconfident investors are more susceptible to the excessive trading behavior than others. Second, our findings are valuable to brokerage firms that dedicate themselves to helping investors make more successful investments. We believe that these brokerage firms will become more profitable if their clients enjoy higher rates of investment return over the long term. Finally, high trading frequency is hazardous to investor wealth, so it is important to educate investors to reduce trading bias.