PORTAGE, IND. — Marcus & Millichap has brokered the $4 million sale of Diamond Plaza in Portage, a city in Northwest Indiana. The 26,524-square-foot retail property is located right off U.S. Route 6. Tarek Chbeir of Marcus & Millichap secured and represented the buyer, a private investor. Josh Caruana, broker of record in Indiana, assisted in closing the transaction. Seller information was not provided.