(1) It shall be unlawful for any broker or dealer which is either a person other than a natural person or a natural person not associated with a broker or dealer which is a person other than a natural person (other than such a broker or dealer whose business is exclusively intrastate and who does not make use of any facility of a national securities exchange) to make use of the mails or any means or instrumentality of interstate commerce to effect any transactions in, or to induce or attempt to induce the purchase or sale of, any security (other than an exempted security or commercial paper, bankers' acceptances, or commercial bills) unless such broker or dealer is registered in accordance with subsection (b) of this section.

          (2) The Commission, by rule or order, as it deems consistent with the public interest and the protection of investors, may conditionally or unconditionally exempt from paragraph (1) of this subsection any broker or dealer or class of brokers or dealers specified in such rule or order.