Section 18. Notwithstanding any general or special law to the contrary, the commissioner may, subject to such terms and conditions as the commissioner may impose, grant a certificate to establish an interim bank, which may be a savings bank, co-operative bank or a trust company, owned by a bank holding company or a banking institution, as defined in section 1 of chapter 167A, or a mutual holding company, as defined in section 1 of chapter 167H, for the sole purpose of facilitating a multi-step corporate transaction involving a bank, as defined in section 1 of chapter 167; provided, however, that the interim bank under this chapter, chapter 167A, 167H, 167I or any other chapter shall not receive deposits or otherwise carry on a banking business under the laws of the commonwealth.