We provide the first study of underwriter-affiliated analysts' pre-IPO research coverage and its impact on stock prices. Using proprietary data on a sample of Chinese IPOs, we document that affiliated analysts make highly overoptimistic forecasts about IPO clients. Analyst hype inflates both the offer price and the aftermarket price. Consistent with the sentiment theory, IPO investors inadequately adjust to analyst hype because the offer price is set sufficiently lower than the aftermarket price. The results hold when we instrument analyst hype with a variable that affects their hyping incentive. We also utilize a regulatory change as a quasi-experiment. Our analysis contributes to the debate about regulations on pre-IPO information provision.

We propose an extrapolative model of bubbles to explain the sharp rise in prices and volume observed in historical financial bubbles. The model generates a novel mechanism for volume: because of the interaction between extrapolative beliefs and disposition effects, investors are quick to not only buy assets with positive past returns but also sell them if good returns continue. Using account-level transaction data on the 2014–2015 Chinese stock market bubble, we test and confirm the model’s predictions about trading volume. We quantify the magnitude of the proposed mechanism and show that it can increase trading volume by another 30%.