Notwithstanding any other law to the contrary, a mutual bank and mutual holding company may invest an amount not to exceed 25 percent of its capital and surplus in the capital debentures, bonds, special deposits, or other debt securities of any other mutual bank or mutual holding company located in this state or in any other state, whether the other bank is in organization or in existence. For purposes of this section, if the investment constitutes more than 50 percent of the capital and surplus of the mutual bank or mutual holding company issuing the capital debentures, bonds, special deposits or other debt securities, the banks involved in the investment transaction shall be deemed affiliates and may receive deposits, renew time deposits, close loans, service loans, and receive payments on loans and other obligations as an agent for each other in the same manner as bank subsidiaries of a bank holding company may do so under subsection (r) of the Federal Deposit Insurance Act, 12 U.S.C. § 1828. The banks shall not be considered branches of each other nor shall the bank making the investment be considered a bank holding company.