"I study battles between short sellers and firms. Firms use a variety of methods to impede short selling, including legal threats, investigations, lawsuits, and various technical actions intended to create a short squeeze. These actions create short sale constraints. Consistent with the...

Corporate events, such as new issues and new lists, appear in waves. These waves imply that the market portfolio has a time-varying weight in new lists, and one can decompose the market return into a fixed weight return plus a timing return. Most of the reduction in aggregate market returns...