Okla. Admin. Code § 735:10-1-9
All safekeeping banks must be approved by the State Treasurer. A safekeeping bank must either be a Federal Reserve Bank which serves Oklahoma, a Federal Home Loan Bank which serves Oklahoma, or a financial institution located in Oklahoma. A financial institution may not deposit securities as collateral with another financial institution that it owns or controls, or which is owned or controlled by the same holding company. Any financial institution which is not already an approved safekeeping bank at the time this rule becomes effective, may request approval by the State Treasurer. The request shall be in writing and must contain information which demonstrates that the financial institution has a demonstrated record of superior performance in the safekeeping of securities for third parties.
Okla. Admin. Code § 735:10-1-9