(a) If the records required to be maintained and preserved pursuant to the provisions of §§ 270.31a-1 and 270.31a-2 are prepared or maintained by others on behalf of the person required to maintain and preserve such records, the person required to maintain and preserve such records shall obtain from such other person an agreement in writing to the effect that such records are the property of the person required to maintain and preserve such records and will be surrendered promptly on request.

(b) In cases where a bank or member of a national securities exchange acts as custodian, transfer agent, or dividend disbursing agent, compliance with this section shall be considered to have been met if such bank or exchange member agrees in writing to make any records relating to such service available upon request and to preserve for the periods prescribed in § 270.31a-2 any such records as are required to be maintained by § 270.31a-1.