(a) Except as provided in paragraph (b) of this section, each person registered as a futures commission merchant must become and remain a member of at least one futures association that is registered under section 17 of the Act and that provides for the membership therein of such futures commission merchant, unless no such futures association is so registered.

(b) The requirements of paragraph (a) of this section shall not apply to a futures commission merchant registered in accordance with § 3.10(a)(3) of this chapter.