Wis. Stat. § 231.17
The authority may invest any funds in bonds, notes, certificates of indebtedness, treasury bills, or other securities constituting direct obligations of, or obligations the principal and interest of which are guaranteed by, the United States; in those certificates of deposit or time deposits constituting direct obligations of any bank that are insured by the federal deposit insurance corporation; in certificates of deposit constituting direct obligations of any credit union that are insured by the national board, as defined in s. 186.01(3m); in certificates of deposit constituting direct obligations of any savings and loan association or savings bank that are insured by the federal deposit insurance corporation; in short-term discount obligations of the federal national mortgage association; or in any of the investments provided under s. 66.0603(1m) (a). Any such securities may be purchased at the offering or market price thereof at the time of such purchase.
Wis. Stat. § 231.17