Each fund may invest any surplus moneys not needed for current obligations in United States Government obligations, United States Treasury notes, investment share accounts in any savings and loan association whose deposits are insured by a Federal agency and certificates of deposit issued by a duly chartered commercial bank. Deposits in savings and loan associations and commercial banks shall be limited to institutions in this Commonwealth and shall not exceed the federally insured amount in any one account. Investments may also be made in any permitted investments of capital or surplus of stock casualty insurance companies set forth in section 602 or 603¹ of the Insurance Company Law of 1921, as may be authorized by regulation approved by the commissioner.