Cal. Fin. Code § 1008

The amount of funds of a bank or trust company that are deposited in any other financial institution (other than a Federal Reserve bank) shall not at any time exceed 10 percent of the sum of shareholders’ equity, allowance for loan and lease losses, capital notes, and debentures of the depositing bank or trust company unless the financial institution has been designated as a depositary for the funds of the depositing bank or trust company by a vote of the majority of the directors of the depositing bank or trust company, and unless the financial institution has been approved by the commissioner as a depositary for the purposes of this section. The commissioner may, in his or her discretion, revoke his or her approval of any such depositary and may, in his or her discretion, limit the amount of funds that may be deposited by any bank or trust company with any other financial institution. A deposit by one bank or trust company with another financial institution shall not be regarded as a loan.