Minn. Stat. § 48.37

In order to exercise the powers herein conferred, any such bank shall invest and keep invested in one or more of the first, second, third, fourth, seventh, and eighth classes of authorized securities, at least 25 percent of its capital, which securities in the amounts above provided shall be duly assigned, transferred to, and deposited with the commissioner provided, however, that no bank and trust shall be required to deposit securities in excess of $1,000,000, and shall be maintained unimpaired as a guaranty fund for the integrity of its trusts and for the faithful discharge of its duties, in connection therewith, with the right to the bank to collect the income thereof and to substitute other like authorized securities of equal amount and value. The commissioner shall carefully examine the securities offered for deposit and, if they comply with all the provisions of law applicable thereto, and, if the bank making such deposit shall possess the qualifications stated in section 48.36 , shall issue to the bank a certificate stating that it is qualified to exercise the powers herein conferred, and, upon the issuance of this certificate and while the same remains in force, the bank may exercise the powers and privileges conferred by sections 48A.07 and 48A.08 .

In case of any increase in the capital of any bank which has qualified hereunder, this certificate shall be and become revoked and the bank shall not thereafter exercise the powers herein conferred until it shall have deposited the required proportion of its capital in authorized securities and received a new certificate that it is qualified hereunder.