Individual and institutional investors can trade German initial public equity offerings on an as-if/when-issued basis before the start of secondary trading. Using actual when-issued trades made by a sample of clients at a large German retail broker during 1999 and 2000, the paper documents that retail buyers consistently overpay for initial public offerings (IPOs) in the when-issued market relative to the immediate aftermarket. The observed willingness to overpay points to sentiment as a driver of retail trading decisions. Consistent with this interpretation and with sentiment affecting prices, IPOs that are aggressively bought by individuals in the when-issued market exhibit high first-day returns as well as poor aftermarket returns relative to benchmarks of similar stocks.

Combining survey responses and trading records of clients of a German retail broker, this paper examines some of the causes for the apparent failure to buy and hold a well-diversified portfolio. The subjective investor attributes gleaned from the survey help explain the variation in actual portfolio and trading choices. Self-reported risk aversion is the single most important determinant of both portfolio diversification and turnover; other things equal, investors who report being more risk tolerant hold less diversified portfolios and trade more aggressively. Less experienced investors similarly tend to churn poorly diversified portfolios. The effect of perceived knowledge on portfolio choice is less clear cut; holding other attributes constant, investors who think themselves knowledgeable about financial securities indeed hold better diversified portfolios, but those who think themselves more knowledgeable than the average investor churn their portfolios more.

We hypothesize that vanity amplifies realization utility in teams; admitting mistakes is particularly painful when mistakes have to be admitted to self and colleagues. Consistent with the Vanity hypothesis, U.S. stock funds run by teams hold on to losers when losers were initiated by a subset of the team (to avoid admitting a mistake to their non-initiating colleagues), when initiators of loser positions are more experienced (to avoid losing authority by admitting mistakes to junior colleagues), and when all colleagues agree that a position is a loser. Vanity is costly – losers held underperform by a risk-adjusted 1% annually.

The preferred risk habitat hypothesis, introduced here, is that individual investors select stocks whose volatilities are commensurate with their risk aversion. The data, 1995–2000 holdings of over 20,000 clients at a large German broker, are consistent with the predictions of the hypothesis: the returns of stocks within each portfolio have remarkably similar volatilities, when stocks are sold they are replaced by stocks of similar volatilities, and the more risk-averse customers indeed hold less volatile stocks. Greater volatility specialization is associated with lower Sharpe ratios, primarily because more specialized investors hold fewer stocks and thereby expose themselves to more unsystematic risk.

The disposition effect is a longstanding puzzle in financial economics. This paper demonstrates that it is not intrinsically at odds with rational behavior. In a rational expectations model with asymmetrically informed investors, trading strategies as predicted by the disposition effect can arise as an optimal response to dynamic changes in the information structure. The model predicts that the disposition behavior of uninformed investors weakens after events that reduce information asymmetries. The data, trading records of 50,000 clients at a German discount brokerage firm from 1995 to 2000, are consistent with this prediction.

A German broker's clients place similar speculative trades and therefore tend to be on the same side of the market in a given stock during a given day, week, month, and quarter. Aggregate liquidity effects, short sale constraints, the systematic execution of limit orders (coordinated through price movements) or the correlated trading of other investors who pick off retail limit orders do not fully explain why retail investors trade similarly. Correlated market orders lead returns, presumably due to persistent speculative price pressure. Correlated limit orders also predict subsequent returns, consistent with executed limit orders being compensated for accommodating liquidity demands.