Does Rule 10b-21 increase SEO discounting?

Short sale constraints prior to seasoned equity offers, imposed by Rule 10b-21 in 1988, are believed to compromise pricing efficiency and contribute to the large temporal increase in offer price discounting. This study provides additional insights by examining shelf-registered offers, which were exempt from pre-issue short sale constraints until 2004. The results suggest that pre-issue short sale constraints do not influence the level of discounting in seasoned equity offers. Moreover, this study reports that the recent temporal increase in discounting is due to a greater prevalence of overnight shelf offers, which are associated with relatively large offer price discounts.