Mich. Comp. Laws § 500.917

Sec. 917. (1) Qualified assets for purposes of section 901 include mortgage-backed securities backed by pools of residential mortgages and rated investment grade by a securities rating organization approved by the commissioner. Any securities described in section 106 of title I of the secondary mortgage market enhancement act of 1984, Public Law 98-440, 15 U.S.C. 77r-1, shall be subject to all the limitations prescribed by this chapter for investments not guaranteed by the full faith and credit of the United States. (2) As used in this section, "mortgage-backed securities" means securities representing an ownership interest in, or as to which payments are secured directly or indirectly by, a pool of mortgages or by the cash flows generated by a pool of mortgages and shall include, but are not limited to, mortgage pass-through securities and collateralized mortgage obligations.