Section 13-703. Investments in railroad, industrial, electric and gas, telephone and waterworks obligations

Notwithstanding the provisions  of  the  code  or  any  other  law to the contrary, the trustee, trustees or
  other officer, board or body having the power to invest the funds  of  a
  pension fund or retirement system maintained, administered, or supported
  by  the city or an agency, or by city funds, may, in addition, invest in
  obligations consisting of notes, bonds, debentures  or  equipment  trust
  certificates  issued under an indenture which are the direct obligations
  of, or in the case of equipment trust certificates, are secured  by  the
  direct  obligations  of,  a  railroad  or  industrial  corporation, or a
  corporation  engaged  directly  and   primarily   in   the   production,
  transportation,  distribution  or  sale  of  electricity  or gas, or the
  operation of telephone or telegraph systems or waterworks,  or  in  some
  combination  of  them;  provided the obligor corporation is one which is
  incorporated under the laws of the United States, or any state  thereof,
  of  the District of Columbia, and said obligations shall be rated at the
  time of purchase within the three highest classifications established by
  at least two standard rating services. The maximum amount that they  may
  invest in such obligations pursuant to this subdivision shall not exceed
  ten  per  centum  of  the assets of a fund; and provided further that of
  said ten per centum not more than two per centum of the assets of a fund
  shall be invested in the obligations  of  any  one  corporation  of  the
  highest  classification and subsidiary or subsidiaries thereof, that not
  more than one and one-half per centum of the assets of a fund  shall  be
  invested in the obligations of any one corporation of the second highest
  classification  and  subsidiary  or  subsidiaries thereof, that not more
  than one per centum of the assets of a fund shall  be  invested  in  the
  obligations  of  any one corporation of the third highest classification
  and subsidiary or subsidiaries thereof.