The commissioner shall prescribe rules with respect to investment advisers licensed under this chapter who have custody of their clients’ securities or funds or who have any power of attorney from their clients to execute transactions as he or she finds to be necessary or appropriate in the public interest or for the protection of investors. The rules may require a minimum capital for those investment advisers or prescribe a minimum ratio between net capital and aggregate indebtedness or both, and may require a fidelity bond.