Insurance companies, personal finance companies, mortgage companies, mortgage insurance companies, building and loan associations, trust companies, fiduciaries, or fiduciary institutions may invest in, or purchase such classes of first liens as are commonly given to secure advances on, or the unpaid purchase price of real estate, including any part of an issue of notes or bonds secured by such first liens, which have been accepted for insurance by the Federal Housing Administrator. The investment or purchase may be made with their funds or the money in their custody or possesion, including but not being restricted to, all trust funds or funds the investment of which is
regulated by law.