The agency may invest in, purchase, or make commitments to purchase any residential mortgage or any obligation secured by a residential mortgage or participation therein, and sell such obligations, residential mortgages, or participations or create pools of such obligations, residential mortgages, or participations held by the agency and issue and sell securities backed by such pools. The agency shall require the seller of such obligations, residential mortgages, or participations purchased by the agency to use the proceeds for the purpose of financing housing developments and residential structures.