IOWA — Stan Johnson Co. has brokered the sale of a four-building industrial portfolio across Iowa for $16.9 million. The properties total nearly 684,000 square feet and are leased to a subsidiary of Magna International Inc. The buildings include 408 and 411 Maplewood Ave. in Williamsburg, 403 S. 8th St. in Montezuma, and 1951 A Ave. in Victor. Rob Gemerchak and Jeff Hughes of Stan Johnson represented the seller, Granite REIT, a Toronto-based publicly traded real estate investment trust. New York-based GMS Equities purchased the portfolio.