40 ILCS 5/22C-123
The pension fund assets transferred to or otherwise acquired by the Fund shall be placed in the custody of a custodian who shall provide adequate safe deposit facilities for those assets and hold all such securities, funds, and other assets subject to the order of the Fund.
Each custodian shall furnish a corporate surety bond of such amount as the board designates, which bond shall indemnify the Fund, the board, and the officers and employees of the Fund against any loss that may result from any action or failure to act by the custodian or any of the custodian's agents, or provide insurance coverages of such type and limits as the board designates. All charges incidental to the procuring and giving of any bond shall be paid by the board and each bond shall be in the custody of the board.
40 ILCS 5/22C-123