Expansion Plans Include Opening Three New Regional Cox Interior Locations  CHICAGO, Jan. 30, 2024 /PRNewswire/ -- In December 2023, 5M Group led a joint venture as the managing partner and completed the acquisition of three hardwood manufacturing companies: Cox Interior, Cox Shavings and Cox Dimensions. Brothers Mark Reiter and Marty Reiter are co-founders and principals of 5M Ventures, a private equity division of their parent company, 5M Group, a commercial real estate development and private equity firm based in Chicago.