Mo. Rev. Stat. § 362.310

Every bank and trust company shall create a fund to be known as a "surplus fund". This fund may be created or increased by contributions or by transfers from undivided profits. The fund up to forty percent of the capital of the bank or trust company shall be used only for the payment of losses in excess of undivided profits; provided, that the excess of surplus over forty percent, upon the approval of the director of finance, may be capitalized as a stock dividend or may be transferred to undivided profits and used for cash dividends in the discretion of the board of directors.