Category 4 investment firms that hold custody of financial instruments with a custodian are expected to establish and maintain a system for assessing the appropriateness of the selection of the custodian and to assess the continued appointment of that custodian periodically as often as is reasonable in the relevant market. The licensee is also expected to make and retain a record of the grounds on which it satisfies itself as to the appropriateness of its selection or, following a periodic assessment, continued appropriateness of the custodian.