Any company organized under the laws of this state, or doing in this state any business mentioned in section 376.010, may at any time change the securities in which its capital or any part thereof is invested, whether the same are deposited with the director of the department of commerce and insurance or elsewhere, for any other securities; provided, that the amount or value of the securities required by sections 376.010 to 376.670 to be deposited with said director shall in no case be diminished or impaired.