17 C.F.R. § 240.16c-2
Any transaction shall be exempt from section 16(c) of the Act to the extent necessary to render lawful any sale made by or on behalf of a dealer in connection with a distribution of a substantial block of securities, where the sale is represented by an over-allotment in which the dealer is participating as a member of an underwriting group, or the dealer or a person acting on the dealer's behalf intends in good faith to offset such sale with a security to be acquired by or on behalf of the dealer as a participant in an underwriting, selling, or soliciting-dealer group of which the dealer is a member at the time of the sale, whether or not the security to be acquired is subject to a prior offering to existing security holders or some other class of persons.
17 C.F.R. §240.16c-2