(A) All assets of a retirement system are held in trust. The commission has the exclusive authority, subject to this chapter and § 9-1-1310, to invest and manage those assets.

(B) If the retirement system invests in a security issued by an investment company registered under the Investment Company Act of 1940 (15 U.S.C. § 80a-1, et seq.), the assets of the system include the security, but not assets of the investment company.

(C) The board shall hold the assets of the retirement systems in a group trust under Section 401(a)(24) of the Internal Revenue Code that meets the requirements of Revenue Ruling 81-100, 1981-1 C.B. 326, as amended by Revenue Ruling 2004-67. Any group trust shall be operated or maintained exclusively for the commingling and collective investment of funds from other trusts that it holds. The board shall be permitted to hold in this group trust funds that consist exclusively of trust assets held under plans qualified under Internal Revenue Code Section 401(a), individual retirement accounts that are exempt under Internal Revenue Code Section 408(e), and eligible governmental plans that meet the requirements of Internal Revenue Code Section 457(b). For this purpose, a trust includes a custodial account under Internal Revenue Code Section 401(f) or under Internal Revenue Code Section 457(g)(3).