Equastone, a San Diego-based real estate investment firm targeting opportunistic, value-added and core-plus real estate and intent on acquiring $1 billion of U.S. office and flex properties over the next two years, closed on its acquisition of four office and R&D properties totaling 239,521 square feet located in Denver's Interlocken Business Park for $21.9 million or approximately $91.43 per square foot.