The Authority shall have power to invest and reinvest any funds held in reserve or sinking funds not required for immediate disbursement in bonds or notes of the United States, bonds of the State of Illinois or of Cook County or of the City of Chicago or of the Chicago Park District or of the Sanitary District of Chicago, or of the Board of Education of the City of Chicago and in bonds or certificates of the Authority at not to exceed their par value or their call price and to sell these securities whenever the funds are needed for disbursement. Such investment or reinvestment of any fund shall not be in conflict with any provisions of any trust agreement securing the payment of bonds or certificates of the Authority.