Mont. Code Ann. § 33-12-113

An insurer may contract with any national or state bank, trust company, or securities brokerage firm to act as custodian for the insurer's securities. The contract must contain an indemnification agreement stating that the custodian is obligated to indemnify the insurer for any loss of the insurer's securities in its custody resulting from the intentional or negligent act or omission of the custodian or the employee, officer, or agent of the custodian.