Mo. Rev. Stat. § 362.130

In any case where such capital notes to be issued as provided under the provisions of sections 362.120 to 362.135 are made retirable in a period less than twenty years after their authorization, the bank or trust company issuing such capital notes may, by a provision inserted therein to the effect, reserve the right from time to time to extend the time for the retirement of said capital notes and, in such event, the bank or trust company so issuing said capital notes may, by vote of a majority of its board of directors, with the consent of the finance director, make such extension.