A broker licensed by the Real Estate Commissioner is exempt from the provisions of Section 25210 when engaged in transactions in any interest in any general or limited partnership, joint venture, unincorporated association, or similar organization (but not a corporation) owned beneficially by no more than 100 persons and formed for the sole purpose of, and engaged solely in, investment in or gain from an interest in real property, including, but not limited to, a sale, exchange, trade, or development. An interest held by a husband and wife shall be considered held by one person for the purposes of this section.