The poison pill is becoming less common as corporate boards become more comfortable working with activist investors instead of adopting an automatically confrontational stance, and no one knows it better than Jana Partners managing partner Barry Rosenstein, who recently wrote about his experiences for The Financial Times. “An increasing number of companies are adopting this more constructive approach. According to FactSet Research, in 2006 34 percent of S&P 500 companies still had poison pills and 41 percent had staggered boards, compared with 7 per cent and 11 per cent in 2013, respectively,” Rosenstein writes. Activist hedge funds outperform Of course,…