When short selling is costly, owners of an asset have greater incentive to become informed than nonowners because trading on negative information is easier for them. Thus, information acquisition concentrates among investors owning the asset. A short selling ban restricts selling to only the relatively more informed investors who own the asset, increasing adverse selection but only on the sell side of the market. Price efficiency declines due to less overall information acquisition because a ban magnifies the disincentive to gather information for investors not owning the asset. Empirical evidence from the 2008 U.S. short selling ban is consistent with these theoretical predictions.

In a standard stock loan, the borrower reimburses the lender any dividends paid while the loan is outstanding. Since these substitute dividends may be taxed differently than dividend payments themselves, some investors have incentives to either remove their shares from lendable supply–if they pay high taxes on substitute dividends–or lend out their shares to arbitrageurs–if they pay high taxes on dividends. Consistent with these incentives, we find a significant tightening of the equity lending market on dividend record days driven by both a contraction of supply and an expansion of demand–although the demand effect appears to dominate. We then exploit the plausibly exogenous nature of these shifts to causally link tightness in the lending market to wider effective spreads in the stock market.