The authors investigate the nature and magnitude of short-selling activity around seasoned equity offerings, the relation between short-selling activity and issue discounts, and the consequences of the Securities and Exchange Commission adoption of Rule 10b-21 in response to concerns about manipulative short-selling practices. Seasoned offerings are characterized by abnormally high levels of short selling and option open interest. Higher levels of such activity are related to lower expected proceeds from the issuance of new shares. Where it could not be circumvented, Rule 10b-21 appears to have curbed short-selling activity and reduced issue discounts.

Underwriters have an incentive to overstate investor interest in order to persuade some investors to purchase shares at a price in excess of their initial estimate of the fair value. We show that this incentive is eliminated when the underwriter commits to secondary market price stabilization. Destroying the underwriter's incentive to overstate interest reduces the total surplus captured by initial investors in initial public offerings. Further efficiency gains are associated with penalty bid systems that permit the underwriter to make the stabilization commitment selectively. Price stabilization can thus be viewed as a bonding mechanism that improves the efficiency of the primary equity market.

We investigate the nature and magnitude of short-selling activity around seasoned equity offerings, the relation between short-selling activity and issue discounts, and the consequences of the Securities and Exchange Commission (SEC's) adoption of Rule 10b-21 in response to concerns about manipulative short-selling practices. Seasoned offerings are characterized by abnormally high levels of short selling and option open interest. Higher levels of such activity are related to lower expected proceeds from the issuance of new shares. Where it could not be circumvented, Rule 10b-21 appears to have curbed short-selling activity and reduced issue discounts.

We investigate the nature and magnitude of short‐selling activity around seasoned equity offerings, the relation between short‐selling activity and issue discounts, and the consequences of the Securities and Exchange Commission (SEC's) adoption of Rule 10b‐21 in response to concerns about manipulative short‐selling practices. Seasoned offerings are characterized by abnormally high levels of short selling and option open interest. Higher levels of such activity are related to lower expected proceeds from the issuance of new shares. Where it could not be circumvented, Rule 10b‐21 appears to have curbed short‐selling activity and reduced issue discounts.