ZIG,
"The "close-out" requirement requires a participant of a registered clearing agency to close out any fail to deliver position in a threshold security that has remained for 13 consecutive settlement days by purchasing securities of like kind and quantity. If the participant does not take action to close out the open fail to deliver position, the participant is prohibited from effecting further short sales in that security without first borrowing or arranging to borrow the security ("pre-borrow" requirement). Market makers are not exempt from this requirement."
It is an attempt by the SEC to diminish NAKED SHORT SELLING of securities. So it is good for CTKH (and other securities) if it works, but some think that the Regulation SHO is not working as well as it was intended.