Financial overconfidence leads to increased trading activity, higher risk taking, and less diversification. In a panel survey of online brokerage clients in the UK, we ask for stock market and portfolio expectations and derive several overconfidence measures from the responses. Overconfidence is identified in the sample in various forms. By matching survey data with participants’ transactions and portfolio holdings, we find an influence of overplacement on trading activity, of overprecision and overestimation on diversification, and of overprecision and overplacement on risk taking. We explore the evolution of overconfidence over time and identify a role of past success and hindsight on subsequent investor overconfidence in line with learning to be overconfident.

Return-chasing investors almost exclusively consider top-performing funds for their investment decisions. When drawing conclusions about the managerial skill of these top performers, they tend to neglect fund volatility and the cross-sectional information contained in the number of funds and the distribution of skill. In multiple surveys of sophisticated retail investors, we show that they do not fully understand the role of chance in experimental samples of fund populations. Respondents evaluate each fund in isolation and do not sufficiently account for fund volatility. They confuse risk taking with manager skill and are thus likely to over-allocate capital to lucky past winners.