Iowa Code § 514B.15

With the exception of investments made in accordance with section 514B.6, the investable funds of a health maintenance organization shall be invested only in securities or other investments permitted by section 511.8 for the investment of assets of life insurance companies or such other securities or investments as the commissioner may permit. For purposes of this section, investable funds of a health maintenance organization are all moneys held in trust for the purpose of fulfilling the obligations incurred by a health maintenance organization in providing health care services to enrollees.