Using three natural experiments, we test the hypothesis that investor overconfidence produces overpricing of high idiosyncratic volatility stocks in the presence of binding short-sale constraints. We study three events: IPO lockup expirations, option introductions, and the 2008 short-sale ban on financial firms. Consistent with our prediction, we show that when short-sale constraints are relaxed, event stocks with high idiosyncratic volatility tend to experience greater price reductions, as well as larger increases in trading volume and short interest, than those with low idiosyncratic volatility. These results hold when we benchmark event stocks with non-event stocks with comparable idiosyncratic volatility. Overall, our findings suggest that biased investor beliefs and binding short-sale constraints contribute to idiosyncratic volatility overpricing.

We find that the level of short interest in a firm's stock significantly predicts future seasoned equity offers (SEOs). The probability of an SEO announcement increases by 34% (decreases by 49%) for firms in the top (bottom) quintile of short interest. We identify a causal impact of short interest on SEO issuance using a novel instrument for short interest based on future litigation filings in close geographical proximity to hedge fund centers. Our findings suggest that corporate decisions can be triggered by the aggregate trading activity of sophisticated outside investors.

We find that institutional investors' local culture of religiosity influences their stock lending decisions and induces short-sale constraints on the underlying stocks. Firms with higher ownerships by blockholders located in more religious counties are associated with higher utilization of lendable shares. This effect is driven by a lower supply of, rather than a higher demand for, lendable shares. Stock lending fees of such firms are higher, and higher short interests of such firms more strongly predict lower future stock returns. Our findings suggest that the cultural norms of institutional investors can create market friction through the stock lending channel.

We propose a model of trading in the over-the-counter corporate bond market where investors can buy and sell bonds through a dealer and can short bonds by borrowing them in the securities lending market. The model predicts that higher dealer inventory costs are associated with lower short interest for bonds, particularly for high-credit-quality bonds. We construct bond-level proxies for inventory costs and provide empirical evidence in support of the model's prediction. We find that much of the dramatic decline in short interest observed since the Great Financial Crisis (GFC) can be explained by an increase in proxies for inventory costs. We document that the short-sale constraints imposed by higher dealer inventory costs have had a negative impact on price efficiency. Our findings suggest that tighter post-GFC regulation may have had unintended consequences for bond market quality.