Mich. Comp. Laws § 500.5209

Sec. 5209. Except as otherwise provided in this section, an insurer shall transact its business under its own name and shall not adopt any assumed name. An insurer, by amending its articles of incorporation, may change its name or take a new name. A nonprofit mutual disability insurer into which a nonprofit health care corporation that is organized under the nonprofit health care corporation reform act, 1980 PA 350, MCL 550.1101 to 550.1704, is merged or consolidated may retain and use trade names in use by the nonprofit health care corporation before the merger or consolidation.