sentences:  John F. Sandner
  
  John F. Sandner, commonly known as Jack Sandner, is an American business executive and community leader who served as the longtime chairman of the Chicago Mercantile Exchange, now the CME Group.During the 1980s and 1990s Sandner served as chairman of the board of the Chicago Mercantile Exchange (CME), the longest elected exchange chairman in the history of the futures industry, Upon his retirement as chairman, Sandner was elected special policy advisor to the CME board of directors in January 1998.