Funds held by a bank or trust company in a fiduciary capacity awaiting investment or distribution shall not be held uninvested or undistributed any longer than is reasonable for the proper management of the account. These funds, including managing agency accounts, may, unless prohibited by the instrument creating the trust or by other statutes of this state, be deposited in the commercial or savings or other department of the bank or trust company, only if the bank or trust company first sets aside under control of the trust department as collateral security:
(1) Direct obligations of the United States or other obligations fully guaranteed by the United States as to principal and interest; or
(2) Bonds or other obligations which constitute general obligations of any state of the United States or municipal subdivision thereof.
The securities so deposited or securities substituted therefor as collateral shall at all times be at least equal in market value to the amount of the funds so deposited, but such security shall not be required to the extent that the funds so deposited are insured by an agency of the federal government.