Complex sentence: Nordy Rockler bought out his brothers shares in the 1960s and assumed full control until 1989, when he became Chairman of the Board of Directors and the presidency began alternating between two of Nordy's children, Ann and Gary.
Split into simpler sentences: Nordy Rockler bought out his brothers shares in the 1960s and assumed full control until 1989, when he became Chairman of the Board of Directors. At that time the presidency began alternating between two of Nordy's children, Ann and Gary.