Regulation SHO, adopted by the SEC in January 2005, sets forth the regulatory framework governing short sales.  Two key provisions, intended to address problems associated with persistent fails to deliver and potentially abusive naked short selling, involve locate and close-out requirements.

Under the locate requirement, a broker-dealer must have reasonable grounds to believe that the security can be borrowed so that it can be delivered on the delivery due date before effecting a short sale order.  

The close-out requirement requires that the clearing broker take immediate action to close out a fail to deliver position in a threshold security that has persisted for 13 consecutive settlement days by purchasing securities of like kind and quantity. Until the position is closed out, the broker may not effect further short sales in that threshold security without borrowing or entering into a bona fide agreement to borrow the security (known as the "pre-borrowing" requirement)

IMPORTANT NOTE:

In October 2008, the SEC amended Regulation SHO with temporary Rule 204T (in place until July 31, 2009) which requires that any broker having a fail to deliver position at NSCC on the settlement date immediately borrow or purchase securities to close out the amount of the fail to deliver position by no later than the beginning of regular trading hours on the following settlement date (the “Close-Out Date”). This close-out requirement requires that the broker take affirmative action to purchase or borrow securities and not offset the fail to deliver position with shares it will receive on the Close-Out Date. Rule 204T applies to all securities not just threshold securities.