It's possible Ackman could succeed at driving big changes if he continues to put the pressure on ADP. Consider that activist Peltz threatened to launch another director battle at DuPont ( DD ) in 2016 after he narrowly lost a boardroom fight with the chemical giant in 2015. In the months following his defeat, DuPont stock price dropped, and it subsequently replaced its CEO, Ellen Kullman. With Peltz hovering, DuPont later agreed to combined with Dow Chemcial in a $150 billion merger, which will break up into three companies in the months to come.