Iowa Code § 495.2: Holding companies.

The provisions of this chapter are hereby made applicable to all corporations, including so-called “holding companies” which by or through the ownership of the capital stock in any other corporation or corporations or a series of corporations owning or controlling the capital stock of each other can or may exercise control over the capital stock of any corporation which owns, uses, operates, or is concerned in the operation of any public gasworks, electric light plant, electric power plant, heating plant, waterworks, interurban or street railway located in the state, or the business carried on by such works or plants.