The provisions of section 4303 of this title shall not apply to any purchase and sale, or sale and purchase, and the provisions of section 4303 of this title shall not apply to any sale, of an equity security of a domestic stock insurance company not then or theretofore held by him or her in an investment account, by a dealer in the ordinary course of his or her business and incident to the establishment or maintenance by him or her of a primary or secondary market otherwise than on an exchange as defined in the Securities Exchange Act of 1934 for the security. The Commissioner may, by such rules and regulations as he or she considers necessary or appropriate in the public interest, define and prescribe terms and conditions with respect to securities held in an investment account and transactions made in the ordinary course of business and incident to the establishment or maintenance of a primary or secondary market. (Added 1965, No. 88, § 4.)