Image source: Getty Images.Just when it seemed that SunEdison was moving toward selling its stake in yieldco TerraForm Power (NASDAQ: TERP) and bringing some stability to the company, the board of directors in the yieldco have adopted a "poison pill" to stave off an unfriendly acquisition. Over the weekend, a policy was put in place to make it hard for any shareholder to acquire over 15% of TerraForm Power's A shares, which are the shares owned by the public.Continue reading