A backstop serves as a type of protection. While not an insurance policy, a business might guarantee that a certain percentage of its offering will be acquired by specific organizations, generally investment banking companies, if the open market fails to attract enough investors and a portion of the offering remains unsold.
Any number of shares purchased by the providing organization under the backstop contract is owned and managed by the providing organization. Once the providing organization has purchased the unsold backstop shares, the issuing firm loses all claims to the ownership of those shares. The issuing company can impose no restrictions on how these shares are treated. The providing organization has total control over these shares and can treat or trade these shares as they see fit as per the regulations that govern the activity overall.